JPH045796Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a perfect dust-proof structure of a feed screw shaft into which a feed nut is screwed.

<Prior Art> Devices equipped with a feed screw shaft into which a feed nut is screwed are known not only for machine tools but also for vehicles, manipulators, etc., and are used in many industrial fields.

For example, as shown in FIG.
Robot arm 1 rotatably supported via
03, one end of a link 104 is pivotally connected via a pin 105, and the other end of this link 104 is connected to a feed screw shaft 107 connected to a drive motor 106.
It is pivotally connected via a pin 109 to a feed nut 108 which is screwed into the feed nut 108 . The feed screw shaft 107 is connected to the column 101 via a pair of link arms 110 and 111.
As shown in FIG. 4a, which is an enlarged view of the feed screw shaft 107, the feed screw shaft 1 is rotatable relative to the bracket 112 by a bearing 113.
07, a pair of bellows 114 are fitted with the feed nut 108 in between for dust prevention. Both ends of the bellows 114 are respectively connected to both end surfaces of the feed nut 108 and to each end surface of the bracket 112 facing the end surfaces of the feed nut 108, so as to completely surround the feed screw shaft 107.

Here, the drive motor 106 is activated to rotate the feed screw shaft 107, and the link 104 is displaced as the feed nut 108 moves, thereby moving the robot arm 103, to which a working device (not shown) is attached to the tip, around the pin 102. When rotating up and down, if the inside of each bellows 114 has a completely sealed structure, a change in the volume inside the bellows 114 may cause it to bulge or come into close contact with the feed screw shaft 107, causing abnormal deformation and causing the feed. The normal movement of the nut 108 may be hindered or the bellows 114 may be damaged.

For this reason, as shown in FIG. 4b showing the appearance of the bellows 114 described above, the bellows 11
Air holes 115 are appropriately formed in the bellows 114.
Bellows 1 communicates the inside and outside and allows outside air to flow freely
It was possible to enter and exit the building within 14 hours.

<Problems to be solved by the invention> Since the conventional bellows 114 is provided with an air hole 115, even if this air hole 115 has a minute diameter, the air cannot be removed if the surrounding environment is poor. There was a risk that minute dust would enter the bellows 114 through the hole 115 and damage the feed screw shaft 107. This kind of malfunction occurs when the feed screw shaft 10
This becomes a particular problem when 7 is a ball screw and the feed nut 108 is a high-precision item such as a ball nut.

<Means for Solving the Problems> In the present invention, the insides of each bellows, which are partitioned into two by a feed nut, are communicated through an air passage provided in the feed nut.

<Operation> As the feed nut moves, the air in the bellows on the side where the volume decreases flows into the bellows on the side where the volume increases through the air passage, and the air pressure in the two bellows is always kept equal. .

<Embodiment> As shown in FIG. 1, which shows the cross-sectional structure of an embodiment of the dust-proof structure of the feed screw shaft according to the present invention, a feed screw shaft is rotatably attached to a bracket 12 at both ends via bearings 11. A feed nut 14 is screwed into the feed nut 13, and a nut holder 15 is integrally fitted into the feed nut 14. Both ends of a pair of bellows 16, which are respectively fitted to the feed screw shaft 13 with the feed nut 14 in between, are connected to the end surface of the bracket 12 and the end surface of the feed nut 14 or the nut holder 15, thereby sealing the inside of the bellows 16. It has a structure. If the bellows 16 is made of rubber, it is best to use vulcanized adhesive or adhesive, and if it is made of metal, brazing or adhesive can be used, but it is of course also possible to connect them mechanically. In this case, it is desirable to interpose a sealing material such as a gasket. A plurality of sets of air passages 17, each of which opens into the bellows 16 at both ends, are formed in a straight line in the feed nut 14 and the nut holder 15. As shown in FIG. 2 showing the structure, a pipe 19 whose both ends communicate with each bellows 16 via a joint 18 may be attached to the feed nut 14 of the feed screw shaft 13 or the nut holder 15. In addition, in these embodiments, the feed nut 14 and the nut holder 15 are
However, there is no problem even if the nut holder 15, which is not in a screwing relationship with the feed screw shaft 13, is omitted, and the shape etc. of the feed nut 14 can be appropriately set as necessary. In addition, the reference numeral 20 in FIG. 1 indicates the bearing 1 attached to the bracket 12.
1 dust cover.

Therefore, when the feed nut 14 is moved along the feed screw shaft 13, the bellows 16 on the compressed side
Since the air inside flows into the bellows 16 on the side to be stretched through the air passage 17, the pressure inside each bellows 16 is always kept constant, and the pressure inside each bellows 16 is kept constant.
There is no possibility that abnormal deformation will occur.

<Effects of the invention> The inside of the bellows can be completely sealed from the outside, and even when the feed nut is moved, problems such as the bellows bulging or coming into close contact with the feed screw shaft do not occur.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view schematically showing one embodiment of the dustproof structure of the feed screw shaft according to the present invention, Fig. 2 is a cross-sectional view schematically showing the main parts of another embodiment, and Fig. 3 is a feed screw shaft. FIG. 4a is a cross-sectional view showing the structure of its main part, and FIG. 4b is a front view showing the external appearance of a part of the manipulator. ...Bearing, 12...Bracket, 13...
Feed screw shaft, 14... Feed nut, 16... Bellows, 17... Air passage, 18... Joint,
19...It's a pipe.

Claims (1)

[Scope of utility model registration request] In a feed screw shaft into which a feed nut is screwed and whose both ends are rotatably supported by a pair of brackets via bearings, one of the feed screws is fitted onto the feed screw shaft and faces one end surface of the feed nut. A first bellows is connected at both ends to the end surface of the bracket and one end surface of the feed nut and has an internally sealed state; a second bellows whose both ends are connected to the end surface of the bracket and whose interior is in a sealed state; and an air passage provided in the feed nut and whose both ends communicate with the first bellows and the second bellows, respectively. Dust-proof construction of the feed screw shaft.