JPH074952U - Oil-impregnated polymer lubricated ball screw - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a ball screw that can automatically and stably supply lubricating oil for a long period of time and that has a long life even in adverse environments such as water, dust, and corrosive gases. [Structure] A ball screw nut (2) having a large number of balls (3) built therein and screwed onto a screw shaft (1) so as to be relatively movable in a linear axis direction by rolling of these balls (3), and a screw groove (1b) of a screw shaft. A lubricating oil-containing polymer member 10 also serving as a sealing material (or a deflector) was attached so that it could be slidably contacted. The lubricating oil gradually exudes with time from the lubricating oil-containing polymer member 10 and performs a lubricating action for a long period of time, and at the same time, the inside of the bearing is shielded from an external bad environment to achieve the above object.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a ball screw, and is particularly suitable for use in an oil-impregnated polymer lubrication system that can be suitably used even in an adverse environment where normal lubrication is difficult, such as an environment where dust, corrosive gas, water, etc. easily enter the interior, or high temperature environment. Regarding ball screws.

[0002]

[Prior art]

 As shown in FIG. 10, a ball screw used in a general environment has grease or grease in a space 4 between a screw shaft 1 and a ball screw nut 2 screwed through a large number of balls 3 therein. Lubricant is filled and lubricated. Further, in order to prevent dust or the like from entering the ball screw nut 2, an annular recess 5 may be provided at the end of the ball screw nut 2 and a seal member 6 may be fitted and attached thereto (seal). Type ball screw).

[0003]

[Problems to be solved by the device]

 However, such a conventional ball screw of lubricating oil or grease lubrication type is consumed because the lubricant filled in the nut 2 flows out to the outside particularly when it is used in a high temperature environment. There was a problem that the supply had to be repeated quickly and in a short period of time.

If the seal member 6 is attached to the end of the nut 2 in order to prevent dust, corrosive gas, water droplets, and the like from entering the inside, friction and wear between the screw shaft 1 and the seal member 6 occur. There was a problem that the torque increased. On the other hand, Japanese Patent Publication No. 63-23239 discloses a technique in which a ball bearing is filled with a lubricating composition which is solidified by heating and melting a mixture of ultra-high molecular weight polyethylene and lubricating grease. However, this is a product in which the above-mentioned lubricating composition is applied to a ball bearing and cannot be applied to a ball screw as it is.

Therefore, the present invention has been made in view of such conventional problems, and it is possible to stably and automatically supply lubricating oil for a long period of time, and in dust, water, high temperature atmosphere. It is an object of the present invention to provide a long-life oil-impregnated polymer lubricated ball screw capable of sufficient lubrication even in an adverse environment where normal lubrication is difficult.

[0006]

[Means for Solving the Problems]

 The present invention that achieves the above object has a screw shaft having a spiral thread groove on the outer peripheral surface and a screw shaft having an inner peripheral surface loosely fitted to the screw shaft and having a thread groove corresponding to the thread groove of the screw shaft. Related to a ball screw having a ball screw nut and a large number of balls rolling in a spiral space between the screw grooves, and lubricating the inside of the ball screw nut in sliding contact with the screw groove surface of the screw shaft. An oil-containing polymer member is attached.

Here, the lubricating oil-containing polymer member may be attached to at least one end of the ball screw nut also as a seal member. Further, the lubricating oil-containing polymer member may be attached to an intermediate position of the ball screw nut also as a deflector.

[0008]

[Action]

 In the oil-impregnated polymer lubricated ball screw of the present invention, the lubricating oil gradually exudes from the lubrication-oil-containing polymer member and is evenly and uniformly supplied to the thread groove surface of the screw shaft, which ensures stable lubrication for a long period of time. Done. Also, by using the lubricant oil-containing polymer member also as the seal member, the inside of the ball screw is shut off from the outside, so a smooth lubricating action is maintained for a long period of time even in adverse environments such as water and corrosive gas atmospheres. To do.

The lubricating oil-containing polymer member used in the ball screw of the present invention is selected from the group of poly α-olefin polymers having basically the same chemical structure such as polyethylene, polypropylene, polybutylene, and polymethylpentene. As a lubricating oil, paraffinic hydrocarbon oils such as poly-α-olefin oils, naphthene hydrocarbon oils, mineral oils, ether oils such as dialkyldiphenyl ether oils, phthalic acid ester / trimellitic acid ester After mixing any of the ester oils, etc. and heating and melting, it is poured into a specified mold and cooled and solidified while pressurizing and molded. Antioxidant, rust inhibitor, antiwear agent, anti-foaming agent It is also possible to add various additives such as extreme pressure agents.

For example, as a concrete manufacturing method of a type in which a lubricant oil-containing polymer member is also used as a seal member, a screw shaft of a ball screw to be used is set as it is at the center of a predetermined mold, or a diameter thereof is used. Mold by setting a screw shaft with a large size of 5 to 100 μm. As a result, the clearance between the screw shaft and the ball screw nut can be made smaller than the conventional seal member (the conventional clearance is about 0.3 to 1 mm), and at the same time, it is formed by the oil gradually exuding from the lubricant-containing polymer member. The oil film can maintain outstanding sealing performance.

The above-mentioned groups of polymers have the same basic structure but different average molecular weights, and range from 1 × 10 ^{3 to} 5 × 10 ⁶ . Among them, those having a relatively low molecular weight of 1 × 10 ³ to 1 × 10 ⁶ and those having an ultrahigh molecular weight of 1 × 10 ^{6 to} 5 × 10 ⁶ are used alone or as needed. Use by mixing. In order to improve the mechanical strength of the lubricating oil-containing polymer member of the present invention, the following thermoplastic resin and thermosetting resin may be added to the above poly α-olefin polymer.

As the thermoplastic resin, various resins such as polyamide, polycarbonate, polybutylene terephthalate, polyphenylene sulfide, polyether sulfone, polyether ether ketone, polyamide imide, polystyrene and ABS resin can be used. As the thermosetting resin, various resins such as unsaturated polyester resin, urea resin, melamine resin, phenol resin, polyimide resin and epoxy resin can be used.

These resins may be used alone or as a mixture. Further, in order to disperse the poly α-olefin-based polymer and the other resin in a more uniform state, a suitable compatibilizer may be added as necessary.

[0014]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the same or corresponding parts as in the conventional case are designated by the same reference numerals. FIG. 1 is a sectional view of an essential part of an embodiment of an oil-impregnated polymer lubricated ball screw, which is applied to a ball screw of a seal type.

A ball screw nut 2 is screwed through a large number of balls 3 to a screw shaft 1 having a spiral thread groove 1 b on an outer peripheral surface 1 a. The ball screw nut 2 has a thread groove 2b corresponding to the thread groove 1b of the screw shaft 1 on the inner peripheral surface 2a, and a ball circulation (not shown) for guiding and circulating the rolling ball 3 in the thread groove 2b. The road has a thick body. A lubricant-containing polymer member 10 is fitted in an annular recess 5 on the end surface of the nut and is fixed to the ball screw nut 2 by a set screw 11.

The lubricating oil-containing polymer member 10 of this example is a low molecular weight polyethylene (molecular weight 1 × 10³~ 5 x 10^Five) 14% by weight and ultra high molecular weight polyethylene (molecular weight 1 x 10 ⁶ ~ 5 x 10⁶) 6% by weight of polyethylene is mixed with 80% by weight of paraffinic hydrocarbon oil as a lubricating oil, heated and melted, and then poured into a predetermined mold and cooled and solidified while being pressurized while being molded. The inner diameter surface 10a is formed in conformity with the shape of the spiral thread groove 1b of the screw shaft 1 and is in contact with the thread groove 1b.

Next, the operation will be described. When the screw shaft 1 rotates, the balls 3 in the ball screw nut 2 roll in the screw shaft rotation direction in the spiral space formed by the opposing screw grooves 1b and 2b, and circulate through a ball circulation path (not shown). Moving. Through the rolling of the ball 3, the ball screw nut 2 is fed in a straight line along the screw shaft 1. When the ball screw is driven in this way, the lubricating oil gradually exudes from the lubricating oil-containing polymer member 10 at the end of the ball screw nut 2 over time and is supplied to the screw groove 1b of the screw shaft 1, and the screw groove 1b The ball 3 rolling in the 1b and the thread groove 2b of the ball screw nut are evenly and evenly distributed, and stable lubrication is performed for a long period of time. Therefore, it is possible to continue a good operation with a low torque for a long time without further supplying the ball screw nut 2 with lubricating oil from the outside.

The lubricant-containing polymer member 10 also functions as a seal member for sealing the end portion of the ball screw nut 2, and shuts the inside of the ball screw nut 2 from the outside atmosphere. This protects the inside of the ball-nut 2 from the water and corrosive gas even when the external atmosphere is a bad environment such as water and corrosive gas, and provides a smooth lubricating action over a long period of time. Can be maintained.

FIG. 2 shows another embodiment. In this embodiment, a spring (garter spring) 15 is inserted between the inner peripheral surface 5a of the annular recess 5 on the end surface of the ball screw nut 2 and the outer peripheral surface 10b of the lubricant-containing polymer member 10. Since this spring 15 pressurizes the lubricant-containing polymer member 10 in the radial direction toward the thread groove 1b of the screw shaft 1 at a constant pressure, the inner diameter surface 10a of the lubricant-containing polymer member 10 is worn even during long-term operation. However, proper contact with the screw shaft 1 is always maintained, and good lubrication can be guaranteed.

The lubricating oil-containing polymer member 10 of this example is made of low molecular weight polyethylene (molecular weight 1 × 10³~ 1 x 10⁶) 10% by weight and ultra high molecular weight polyethylene (molecular weight 1 × 10 ⁶ ~ 5 x 10⁶) 5% by weight of polyethylene and 85% by weight of dialkyldiphenyl ether oil as a lubricating oil are molded. FIG. 3 shows still another embodiment.

In this embodiment, a preload in the thrust direction is applied to the lubricating oil-containing polymer member 10 shown in FIG. That is, the recess 5 at the end of the ball screw nut 2 is deepened and a disc spring (or a coil spring) 16 is provided at the back of the lubricant-containing polymer member 10. The spring 16 presses the lubricating oil-containing polymer member 10 parallel to the screw shaft 1 toward the outside of the nut with a constant pressure to axially press the inner diameter surface 10a against the surface of the thread groove 1b of the screw shaft to cause wear. Even so, proper contact is maintained.

The lubricating oil-containing polymer member 10 of this example is made of low molecular weight polyethylene (molecular weight 1 × 10³~ 5 x 10^Five) 14% by weight and ultra high molecular weight polyethylene (molecular weight 1 x 10 ⁶ ~ 5 x 10⁶) 6 wt% of polyethylene is mixed with 80 wt% of paraffinic hydrocarbon oil as a lubricating oil, melted by heating, poured into a predetermined mold, and then cooled and solidified while being pressurized and molded. .

FIG. 4 shows still another embodiment. In this embodiment, a brush seal normally used for a seal type rolling ball screw is formed by incorporating a lubricant-containing polymer member 10. Action. The effect is almost the same as the case of Fig. 1, but the outer peripheral surface of the threaded shaft 1 of the rolled ball screw, which does not have the dimensional accuracy of the cutting process, can be surely contacted and the sealing and lubricating action can be achieved. it can.

The lubricating oil-containing polymer member 10 of this example is also made of low molecular weight polyethylene (molecular weight 1 × 10 5).³~ 5 x 10^Five) 14% by weight and ultra high molecular weight polyethylene (molecular weight 1 x 10 ⁶ ~ 5 x 10⁶) 6 wt% of polyethylene is mixed with 80 wt% of paraffinic hydrocarbon oil as a lubricating oil, melted by heating, poured into a predetermined mold, and then cooled and solidified while being pressurized and molded. . 5 to 8 show still another embodiment.

In this embodiment, the screw of the circulation portion of the ball screw nut 2 is usually used for backing up the tube tongue portion 21 of the circulation tube 20 of the ball screw of the tube circulation path type and for scooping up the ball 3. The lubricating oil-containing polymer member 10 is used as the "deflector" 22 used by fitting in the groove 2b. As shown in FIG. 6, the lubricant-containing polymer member 10 as a deflector is composed of a curved thread groove fitting portion 22a and a mounting portion 22b branched therefrom, and has a screw 22c at the tip of the mounting portion 22b. ing. The cross-sectional shape of the screw groove fitting portion 22a is substantially rectangular as shown in FIG. 8, and the corner portion 22d is in contact with the groove surface of the screw groove 1b of the screw shaft 1. The mounting portion 22b is inserted into a radial through hole 24 formed in the circulation portion of the ball screw nut 2, and a nut 25 is screwed and fixed to a male screw 22c protruding to the outer surface of the ball screw nut 2.

In this way, from the lubricant-containing polymer member 10 as a deflector fitted and attached to the thread groove 2b on the inner peripheral surface of the ball screw nut 2, the thread groove 1b of the rotating screw shaft 1 Lubricating oil gradually exudes over time to the contact portion and is supplied to the thread groove 1b, and evenly spreads over the balls 3 rolling in the thread groove 1b and the thread groove 2b of the ball screw nut, for a long time. Stable lubrication is performed for a long time.

According to this embodiment, in addition to the backup function of the tube tongue portion 21 which is the original function of the deflector and the scooping action of the balls 3, an automatic lubricating oil supply action is performed for a long period of time. In an emergency in which all the balls 3 have been removed, the lubricating oil-containing polymer member 10 as a deflector fitted in the screw groove 1b of the screw shaft 1 serves as a female screw and is used as a slide screw. It also has the fail-safe function of being able to do it.

The lubricating oil-containing polymer member 10 of this example is also made of low molecular weight polyethylene (molecular weight 1 × 10³~ 5 x 10^Five) 14% by weight and ultra high molecular weight polyethylene (molecular weight 1 x 10 ⁶ ~ 5 x 10⁶) 6 wt% of polyethylene polymer is mixed with 80 wt% of paraffin hydrocarbon oil as a lubricating oil, melted by heating, poured into a predetermined mold, and then cooled and solidified while pressurizing and molded. .

In each of the above embodiments, the space 4 between the screw shaft 1 inside the ball screw nut 2 and the ball screw nut 2 (the spiral ball formed by the opposing screw grooves 1b, 2b) Lubricants such as normal grease and lubricating oil may be enclosed in a space other than the rolling path). Also, instead of enclosing a lubricant such as ordinary grease or lubricating oil in the internal space 4 of the ball screw, the space 4 is filled with a mixture of the raw material polymer of the lubricating oil-containing polymer member and the lubricating oil and heated. A structure in which the lubricating oil-containing polymer member 10 is filled in the entire internal space 4 may be formed by melting and then cooling and solidifying. In this case, as shown in FIG. 9, both ends of the ball screw nut 2 may be filled with the lubricating oil-containing polymer member 10 so that both ends of the ball screw nut 2 perform a sealing action. The ball screw grooves 1b and 2b and the ball 3 are directly lubricated.

Further, depending on the usage conditions of the ball screw, the lubricating oil-containing polymer member 10 may be attached only to one of the recesses 5 at both ends. Further, the sealant-type lubricating oil-containing polymer member 10 of each embodiment shown in FIGS. 1 to 4 and the "deflector" 22 also-type lubricating oil-containing polymer member 10 can be used together.

[0031]

[Effect of device]

 As described above, in the oil-impregnated polymer lubricated ball screw of the present invention, the ball-screw nut is operated because the lubricant-containing polymer member that is in sliding contact with the thread groove surface of the screw shaft is installed inside the ball screw nut. Then, the lubricating oil in the lubricating oil-containing polymer member gradually exudes over time, and is automatically and uniformly supplied to the contact surface between the ball screw groove and the ball, and good lubrication is performed for a long period of time. In addition, since the interior of the ball screw nut is protected from the outside by a lubricant-containing polymer material, the ball screw has a sufficiently long life even in adverse environments such as dust, water, and high temperature environments where normal lubrication is difficult. Can be provided.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an essential part of an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a main part of another embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a main part of another embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of a main part of another embodiment of the present invention.

FIG. 5 is an outline view of a ball screw according to still another embodiment of the present invention.

FIG. 6 is a perspective view of a main part of an oil-impregnated polymer member as a deflector installed in the interior shown in FIG.

7 is a sectional view taken along line VII-VII of FIG.

8 is a vertical cross-sectional view of the main part of the embodiment of VIII-VIII in FIG.

FIG. 9 is a vertical sectional view of a ball screw according to still another embodiment of the present invention.

FIG. 10 is a vertical sectional view of a conventional ball screw.

[Explanation of symbols]

 1 Screw Shaft 1b Thread Groove 2 Ball Screw Nut 2b Thread Groove 3 Ball 10 Lubricating Oil Containing Polymer Member

Claims (1)

[Scope of utility model registration request] 1. A screw shaft having a spiral thread groove on an outer peripheral surface thereof, and a ball screw nut having an inner peripheral surface loosely fitted to the screw shaft having a thread groove corresponding to the thread groove of the screw shaft, A ball screw having a large number of balls rolling in a spiral space between both screw grooves, wherein a lubricating oil-containing polymer member that is in sliding contact with the screw groove surface of the screw shaft is attached inside the ball screw nut. Oil-impregnated polymer lubricated ball screw characterized by.