JPH0585792B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary seal structure for a portion that transfers liquid between a fixed tube and a rotating tube. Therefore, it can be used as a non-contact rotary seal structure in the cooling fluid supply section or recovery section of the main shaft or turbine shaft of a machine tool.

[Conventional technology]

Conventionally, in order to prevent liquid leakage in the liquid supply and recovery sections between the fixed tube and the rotating tube, when the relative rotational speed of both tubes is low, an O-ring or the like is inserted, or when the relative rotational speed of both tubes is low, In this case, sealing was performed by bringing a tungsten carbide member into contact.

[Problem to be solved by the invention]

However, in the case of high-speed rotation, the system in which the fixed tube and the rotating tube are in direct contact generates a large amount of heat in that part, which causes seizure, making it impossible to use.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to effectively seal against liquid leakage at a connection portion with a fixed tube even when the rotating tube rotates at high speed.

[Means to solve the problem]

In view of the above object, the present invention provides a rotary seal structure for a portion that transfers liquid between a fixed circular tube and a rotating circular tube, wherein the fixed circular tube and the rotating circular tube have a radial distance. and an insertion portion that is fitted into each other in the longitudinal direction, an annular groove is provided on a surface of the fixed circular tube facing the rotating circular tube in the insertion portion, and a suction path communicating with the groove is provided. A rotary seal structure is provided, characterized in that it is connected to a suction device.

[Effect]

The liquid being supplied or the liquid being collected leaks between the inserted portion of the fixed circular tube and the rotating circular tube in the slight radial direction, but the liquid leaks into the annular groove provided in the fixed circular tube at the inserted portion. Accumulates temporarily. When this is absorbed through the suction path opened in the annular groove, the air is sucked from the side of the inserted portion that is open to the atmosphere in the radial direction, and the flow of the air causes liquid leakage. can be effectively sealed.

〔Example〕

The present invention will be described in more detail below based on embodiments shown in the accompanying drawings.

First, referring to FIG. 1, the distal end of a fixed circular tube 10 having a center hole 10a is inserted into the rear end of a rotary circular tube 14 provided concentrically with the fixed circular tube 10. Between the inner circumferential surface 14a of the rotary circular tube 14 and the outer circumferential surface 10b of the insertion portion of the fixed circular tube 10,
It is formed to have a radial distance δ of about 20 μm to 100 μm. In this embodiment, from the fixed circular tube 10 to the rotating circular tube 14, for example, the rotating circular tube 1
Arrow A to supply cooling liquid for 4 and its bearings.
The coolant is flowing in the direction of. A predetermined pressure is applied to this coolant in order to overcome the flow path resistance, and a part of the coolant that has flowed into the rotary circular tube 14 enters the annular space having the above-mentioned minute dimension δ. If no measures are taken, the information will be leaked to the outside.

In the present invention, an annular groove 16 is formed in the longitudinal center portion 10b of the insertion portion of the fixed circular tube 10, and a suction path 18 opening to the groove 16 is further formed in the fixed circular tube 10. According to this configuration, liquid that has entered the annular space between the rotating circular tube 14 and the fixed circular tube 10 in the insertion portion temporarily accumulates in the annular groove 16. The liquid that has flowed into this groove 16 is
The water is sucked by a suction pump 20 connected to 8. At this time, in the annular groove 1, the annular groove 1
Between the position 6 and the end position open to the atmosphere, air is sucked in from the outside as a result of the suction action of the suction pump 20, and the air is always directed toward the annular groove 16 during suction. A flow occurs. Therefore, although the suction pump 20 suctions a mixed fluid of liquid and air, leakage of the liquid can be effectively prevented by the action of the air flow. However, if the surrounding environment is air containing oil mist or dust, the suction may lead to blockage or other problems, which is undesirable. In that case, a compressed air source 22 capable of supplying fresh air is connected to the annular space, so that slightly compressed fresh air is supplied between the annular spaces.

Next, FIG. 2 shows a case where the present invention is applied as a seal structure in a liquid recovery section.
That is, an example will be shown in which liquid flows from the rotary circular tube 14' to the stationary circular tube 10' and is recovered. The rotating circular tube 14' is inserted into the fixed circular tube 10', and there is a gap of about 20 μm to 100 μm between the outer circumferential surface 14'b of the rotating circular tube 14' and the inner circumferential surface 10'a of the fixed circular tube 10'. The inner circumferential surface 1 of the fixed circular tube 10' at the longitudinal center of the insertion portion forms a space with a minute radial dimension δ.
An annular groove 16' is formed in O'a, and the bottom of the groove 16' communicates with the suction passage 18'. The operation of the seal structure in this case is the same as in the case of FIG. 1, so a description thereof will be omitted.

In FIG. 3, in order to cool the main shaft 32 of the machine tool, the main shaft 32 is
A cooling liquid is supplied into a central circular tube 30 provided in the central circular tube 30 that rotates together with the main shaft 32, and is returned through the outside of the central circular tube 30 at its tip, for example, to the outer periphery of the central hole 10a of the fixed circular tube 10. The cooling liquid is recovered through the annular return path 34 provided.

The center hole 10a of the fixed circular tube 10 has a diameter of 20 μm.
The central circular tube 30, which is formed to have a radial tube dimension δ' of about ~100 um, is partially inserted, and the fixed circular tube 10 is partially inserted into the main shaft 32, and the radial direction 〓 Distance δ is 20 μm ~
It is about 100um. An annular groove 16 is formed in the outer circumferential surface 10b of the inserted portion of the fixed circular tube 10 in the longitudinal center thereof, and a suction path 18 opened at the bottom of the groove 16 is provided in the fixed circular tube 10. ing. According to the above configuration, first, the cooling liquid is supplied from the center hole 10a of the fixed circular tube 10 to the rotating central circular tube 3.
When supplying to 0, part of the cooling liquid from the annular gap having the above-mentioned gap dimension δ' will mix with the cooling liquid on the return trip, but since the liquid is the same, there is no particular problem. do not have. When the coolant flowing out from the tip of the central circular tube 30 and returning through the outside of the central circular tube 30 flows into the annular return path 34 of the fixed circular tube 10, it touches the main shaft 32 and the outer circumference of the fixed circular tube 10. A part of the cooling liquid on the return path enters the space between the surface 10b and the surface 10b.
This infiltrated liquid is effectively prevented from leaking to the outside by an action similar to that described in the embodiment shown in FIG. The seal structure shown in FIG.
The annular groove 16 and the suction path 18 need only be provided on one side, and the sealing structure is simple.

In the main shaft 32 that rotates at high speed and requires the seal structure according to the present invention shown in FIG.
It is also not easy to lubricate the bearings of the main shaft. Bearings are normally lubricated using the grease method when the DmN value is around 700,000, the oil-air method when the DmN value is around 1.5 million, the oil jet method when the DmN value is around 2 million, and the underlace method when the DmN value is around 3 million.
However, it uses an underlace method.
When the DmN value is about 3 million, lubricating oil is not necessarily supplied sufficiently, which may cause seizure of the bearing. In this case, by using the present invention, which allows a coolant containing lubricating oil to be supplied into the rotating main shaft and which can be easily recovered effectively, it is possible to easily handle the case where the DmN value is large as described above. ,
Moreover, the liquid can be reliably supplied to the bearing. This is shown in FIG. That is, the lubricating coolant supplied into the main shaft 32 passes through the supply hole 38 provided in the radial direction of the main shaft 32, and is applied to the inner periphery of the inner race 36 of the bearing 34 based on the centrifugal force caused by the rotation of the main shaft. It is supplied into the annular groove 36b. The coolant supplied into the groove 36b is directly supplied to the lower part of the bearing 34 through holes 36a, which are bored in the radial direction of the inner race 36 and arranged in an appropriate number in the circumferential direction, and flows into the housing. . In this case, the amount of coolant supplied increases as the rotational speed of the main shaft 32 increases due to the action of centrifugal force.
It also has the effect of automatically securing the required amount. Here, the right side of the spindle device in FIG. 4 is constructed as shown in FIG. 3, and the supply hole 38 may be considered to be connected to the central circular pipe 30 in FIG. 3.

Furthermore, supply of lubricating oil to the bearings using the configuration shown in FIG. 4 is possible only for a short time even if the seal structure shown in FIG. 3 is not adopted. That is, by storing lubricating oil in the sealed rotary shaft 32 and rotating the rotary shaft, it is possible to lubricate the bearing 34 until the stored lubricating oil is used up.

〔Effect of the invention〕

As is clear from the above description, according to the present invention,
It is possible to provide a rotary seal structure that effectively seals the liquid without leaking even during high-speed rotation when transferring liquid between the fixed circular tube and the rotating circular tube.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing one embodiment of the rotary seal structure according to the present invention, Fig. 2 is a cross-sectional view showing another embodiment of the rotary seal structure according to the present invention, and Fig. 3 is a cross-sectional view showing an embodiment of the rotary seal structure according to the present invention. FIG. 4 is a cross-sectional view of a rotary seal structure according to the present invention applied thereto. FIG. 4 is a schematic cross-sectional view showing a structure for stably supplying lubricating oil to a bearing. 10, 10'... Fixed circular tube, 14, 14'... Rotating circular tube, 16, 16'... Annular groove, 18, 18'...
... Suction path, 20 ... Suction pump, 30 ... Central circular pipe, 32 ... Main shaft, 34 ... Annular return path.

Claims (1)

[Scope of Claims] 1. A rotary seal structure for a portion that transfers liquid between a fixed circular tube and a rotating circular tube, wherein the fixed circular tube and the rotating circular tube have a radial distance. The suction device has insertion portions that are fitted into each other in the longitudinal direction, an annular groove is provided on the surface of the insertion portion facing the rotating circular tube of the fixed circular tube, and a suction path communicating with the groove is provided. A rotary seal structure characterized by being connected to. 2. A fixed circular pipe provided with an inner circumferential passage for supplying liquid and a recovery passage for recovering liquid outside the inner circumferential passage, and having a radial gap and inserted in the longitudinal direction of the inner circumferential passage. an inner circular tube that rotates with a rotated portion;
the fixed circular tube and a rotating outer circular tube having a radial tube and an insertion portion fitted on the outside of the fixed circular tube, the fixed circular tube in the insertion portion of the outer circular tube; A rotary seal structure characterized in that an annular groove is provided on the outer circumferential surface of the rotary seal, and a suction path communicating with the annular groove is provided in the fixed circular tube to connect a suction device.