JPS62137413A - Orifice throttle type gas bearing - Google Patents

Abstract

PURPOSE:To enlarge the application range by providing a tapped hole of the same diameter as that of a pocket between an air supply passage and the pocket, thrusting a bolt having a small-diameter through hole and a slot groove in the axial direction into the tapped hole, and varying an orifice throttle and the capacity of the pocket. CONSTITUTION:An air supply passage 3 of a diameter (d) and a tapped hole 10 of a diameter d2 smaller than the diameter (d) are bored in a bearing body 1, and a bolt 11 having a through hole 4 of a smaller diameter d1 bored in the axial direction is thrust into the tapped hole to form an orifice throttle portion. The bolt 11 is provided with a slot groove 9 on the air supply passage 3 side, and capable of moving in the tapped hole 10 to vary the capacity of a pocket 5. Thus, the capacity of the pocket 5 is adjusted to prevent the generation of unstable vibration and to increase rigidity and load capacity, so that the application range can be remarkably enlarged.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention is an orifice throttle type that supports a load in a non-contact manner by jetting high-pressure gas onto a bearing surface through a constriction to form a pressure distribution. Regarding gas bearings.

(Prior art) As shown in Fig. 2, the orifice restrictor of a gas bearing is usually bored in the bearing body (1), followed by an air supply passage (3) with an inner diameter (d), followed by a through hole with a small diameter (dI). A hole (orifice constriction part (7) installed at 41V) is formed integrally with the bearing body (a, When air is introduced, the small diameter through hole (
4) Due to the complete passage, the pressure decreases to (PO), and a throttling effect occurs (po<ps).

Furthermore, the depth b is the diameter (d2) from the through hole (4) to the bearing surface ζ-(8) of the bearing body (11) and the clearance (6) between the bearing surface (9) of the mating member (2). ) pocket (5
) (d2=d may also be acceptable), and the gas acts as a pressure reservoir in the orifice restriction.

(Problems to be Solved by the Invention) By the way, when the volume of the pocket portion (5) exceeds a certain value, unstable vibrations caused by the compressibility of the gas cause a mechanical hammer. The conditions for the occurrence of unstable vibrations can be obtained by solving the Reynolds equation, which is the gas state equation, and the Navier-Stoke equation, which is the equation of motion, to find the conditions under which the damping term is negative. The larger the pressure (Ps) is, the more likely it is that seeds with larger pocket volumes will be generated. Under practical usage conditions, this problem tends to occur when the total pocket volume of each air supply hole that makes up the gas bearing is approximately twice the volume of the gas lubricant film formed by the area of the bearing and the bearing clearance. It is known.

Therefore, although orifice throttle type gas bearings have greater rigidity and load capacity than other self-throttled type gas bearings, their weakness is that they are prone to unstable vibrations. In order to completely prevent this, the air supply pressure (Ps) may be unavoidably lowered during use, but this is not preferable because it completely reduces bearing rigidity and load capacity.

(Means for Solving the Problems) The present invention has been made in order to prevent the above-mentioned unstable vibrations (') and to make it possible to adjust the volume of the pocket portion of the air supply hole. This invention relates to a gas bearing in which a screw hole is provided between the pockets, and a small diameter through hole is drilled in the screw hole in the entire longitudinal direction, and an orifice restriction is formed by screwing into the screw hole.

(Embodiment) An embodiment of the present invention will be described with reference to FIG. 1. It is composed of a bearing body (1) and a mating member (2), and the bearing body communicates with an air supply source (not shown) and is supplied with high-pressure gas. A pressure-fed air supply passage (3) of diameter (d) is drilled. Further, following the air supply passage, there is a female screw hole Q having a smaller diameter (d2) than the air supply passage.
G is drilled, and a through hole with a small diameter (d2) in the axial direction (
4) The fully opened bolt C11) is screwed in and the orifice constriction portion (7) is completely formed. The bolt has an air supply passage (3
) side is provided with a slotted groove (9), and by inserting a screwdriver from the air supply passage side and fully rotating the bolt (3), it can be moved within the female threaded hole α0). With this configuration, the lower end surface α of the bolt α and the bearing surface (8
) can be freely adjusted, and the volume of the formed pocket (5) can be completely varied. Bearing body (II bearing surface (8)
A gap (6) of distance (hl) is formed between the bearing surface (9) of the mating member (2) and the diameter (d2) of the pocket (5) in the air supply passage (3). diameter (d
), but it goes without saying that it can be made equal to the diameter of the air supply passage if necessary. Furthermore, although a radial bearing is shown in the embodiment, the present invention can also be applied to a thrust bearing.

(Function) The gas at the supply pressure (Ps) passes through the through hole (4) and is throttled down to the pressure (PO).
), it is forced into the bearing gap (6), forms a pressure distribution on the bearing surface, and performs a bearing action. If unstable vibration occurs due to setting conditions such as air supply pressure or bearing clearance, immediately turn bolt O fully using a screwdriver, etc.
By adjusting the position of the bolt (3), the total volume of the pocket (5) is adjusted to prevent the occurrence of unstable vibrations.

(Effects) In the present invention, as described above, the position of the bolt (3) is adjusted with a simple operation and the volume of the pocket (6) is made variable, so unstable vibrations are eliminated. Compared to other self-drawn type gas bearings, bearings can theoretically have higher rigidity and load carrying capacity.Although they can be made larger, they are prone to unstable vibrations. Manufacture was simple, as it was only necessary to screw in the bolts that had been opened, and the range of use of Orice throttle type gas bearings was greatly expanded, promoting their practical use.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of the present invention, and FIG. 2 is a sectional view of a main part of a conventional product. 3... Air supply passage 4... Through hole 5... Pocket 6... Bearing clearance 7... Orifice throttle 9... Slotted groove 11... Bolt agent Patent attorney Jun Kawachi 2 ylJ1 Figure 2

Claims (3)

[Claims] (1) In an orifice throttle type gas bearing having an air supply passage communicating with an air supply source, an orifice constriction part following the air supply passage, and a pocket opening into the bearing clearance through the orifice constriction part, the air supply passage and A screw hole is provided between the pockets, a bolt having a small diameter through hole drilled in the axial direction is screwed into the screw hole, the through hole is used as an orifice restriction, and the volume of the pocket is made variable. Orifice throttle type gas bearing. (2) The orifice throttle type gas bearing according to claim 1, wherein the screw hole has the same diameter as the air supply passage. (3) The orifice throttle type gas bearing according to claim 1, wherein a slotted groove is carved in one end of the bolt.