JPS5814280Y2 - Sealing device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sealing device for a threaded portion of a screw shaft that rotates and slides in the axial direction, which is used in a vertical mill reduction screw, a horizontal mill reduction screw, a screw type jack, etc.

FIG. 1 shows a screw shaft equipped with a conventional sealing device and its drive unit.

In FIG. 1, a screw shaft 2 is provided to pass through a casing 1, and a nut 3 is engaged with the screw shaft 2. As shown in FIG.

The nut 3 is fixed to the casing 1 with a key 4 and a bolt 5, so that when the screw shaft 2 rotates, the screw shaft 2 itself moves in the axial direction.

A worm wheel 6 is rotatably provided in the casing 1 concentrically with the screw shaft 2 by a bearing 7, and meshes with a worm 8.

The worm wheel 6 has an axial key 9 on its inner peripheral surface, and the key 9 slides into an axial key groove 10 of the screw shaft 2 to transmit the rotation of the worm wheel 6 to the screw shaft 2. It looks like this.

(In addition, in the drawing, key 9 is set at 90° for ease of illustration.
(shown rotated from a predetermined position) Therefore, as the worm 8 rotates, the screw shaft 2 slides in the axial direction while rotating.

The sliding surfaces of these structures, such as the worm 8 and worm wheel 6, the key 9 and keyway 10, the screw shaft 2 and the nut 3, slide while being subjected to high surface pressure, so lubricating oil is supplied. There is.

Furthermore, scale, dirt, water, etc. usually exist outside the casing 1, and the equipment is used in a bad environment.

For this reason, it is necessary to prevent lubricating oil from leaking out of the casing and to prevent scale, dirt, water, etc. from entering from the outside.A screw seal 11 is attached to the casing 1 as a sealing device by a seal holder 12 and a seal presser 13. It is used as a reference.

This threaded seal 11 has an internal threaded portion 11A that engages with the thread of the threaded shaft 2, and seals by connecting the internal threaded portion 11A to the threaded groove of the threaded shaft 2.

Such a contact-type sealing device has the drawback that during use, a gap is created due to wear, reducing the sealing effect and shortening the service life.

Furthermore, there was also a deficiency in that the keyway 10 of the screw shaft 2 significantly deteriorated the sealing effect.

It is an object of the present invention to provide a sealing device that corrects these drawbacks.

According to the present invention, there is provided a sealing device that has a thread that engages in a threaded valley of a screw shaft without contact, and that performs sealing by spouting pressurized fluid (preferably pressurized air) from the tip of the thread. provided.

An embodiment of the present invention shown in FIG. 2 will be described below.

A seal device main body 14 is attached to the seal holder 12.

The sealing device main body 14 has a thread 14A on its inner circumferential surface that has the same pitch as the thread of the screw shaft 2, but engages with the groove 2A of the thread of the screw shaft 2 in a non-contact manner.

That is, the thread 14A is formed to be slightly smaller than the two thread valleys of the screw shaft, and a small gap g is formed between them.

The sealing device main body 14 usually has three threads, the outer thread has a slit 1516 that opens at the threaded end, and the center thread has a large number of holes 1T.

Furthermore, inside the sealing device main body 14, each Surin N5,1
6 and a pressure chamber 18 communicating with the hole 17,
A pipe 19 is connected to this pressure chamber 18, and is connected to an external pressurized air supply source (not shown).

Next, the sealing action of the above sealing device will be explained.

Pressure air supplied to the pressure chamber 18 is supplied to the hole 17 and the slit 1.
It erupts from 5.16.

The pressurized air ejected from the slits 15 and 16 forms an air curtain between the screw shaft 2 and the sealing device main body 14, and together with the pressurized air ejected from the central thread hole 17, pressure is created between the air curtains on both sides. form a region.

This pressure area separates and seals the inside and outside of the casing.

Furthermore, the jet stream from the slit also has the effect of pushing back water, lubricating oil, etc.

In addition, in the above embodiment, the pressure chamber 18 of the sealing device main body 14
Although pressurized air was supplied to the system, it is also possible to use a fluid other than pressurized air.

Furthermore, the number of threads on the inner surface of the sealing device main body 14 is not limited to three, but may be two.

As described above, the sealing device of the present invention provides the following advantages.

0) Since it is a non-contact type, there is no reduction in sealing effectiveness due to friction, etc.

(2) It is also effective for key grooves etc. provided on screw shafts.

(3) Can be installed in the same way as conventional screw seals.

(4) Since it is a non-contact type, there is no need to consider the seal material.

(5) Extremely effective for sealing large diameter screw shafts.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional sealing device, and FIG. 2 is a sectional view showing an embodiment of the present invention. 1...Casing, 2...Screw shaft, 2
Person...Screw valley, 12...Seal holder, 14...Seal device body, 14A...
...Screw thread, 15, 16...Slit, 17
...hole, 18...pressure chamber, 19...
···Piping.

Claims (1)

[Scope of utility model registration request] A sealing device for a screw shaft that moves in the axial direction while rotating, the screw shaft having a trough and a crest on an inner peripheral surface that do not contact the crests and troughs of the screw shaft. A circular arc-shaped main body that engages, a fluid ejection passage that opens at the tip of the crest of the main body and extends into the crest of the main body, and a pressure chamber that is formed within the main body and communicates with the fluid ejection passage. A sealing device comprising: a gap formed between the crests and troughs of the main body and the crests and troughs of the screw shaft, communicating with an external space from both ends of the main body.