JPH1151145A - Side lid type ball screw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly transfer a ball between a load region and a non-load region by moving a connection body by each ball in the load region, guiding each ball by the connection body in the non-load region, and forming a guide part which guides the ball to a conversion passage in each direction at both ends of the non-load region communicated with the load region. SOLUTION: Four belt parts of a ball connection body having an end 4 are slidably fitted in a ball return hole 7 to form a guide groove bar which guides a connection body 10 thereof. Moreover, a guide part which is linearly continuous with a load transfer groove 6 side in the direction of tangential line along a lead angle is formed in a direction conversion passage 8. A ball 9 of the ball connection body having an end 4 is transferred while applying load between a ball transfer groove 5 and a load transfer groove 6, escapes from the load region constituted by the load transfer groove 6, and enters the guide part. The ball 9 is guided to the connection body 10 of the ball connection body having an end 4 from this instant. It moves in the direction of tangential line along the lead angle of the load transfer groove 6, leaves the ball transfer groove 5, and enters the direction conversion passage 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw shaft and a nut member which are screwed together through a number of balls, and a rotary movement of a motor or the like is linearly moved in a slide portion of a machine tool or an industrial robot. More particularly, the present invention relates to a side cover type ball screw device having a structure in which a side cover having a direction change path for circulating balls at both ends of a nut member is attached.

[0002]

2. Description of the Related Art In general, a ball screw device has a screw shaft having a spiral ball rolling groove on an outer peripheral surface, and a ball rolling groove facing an inner peripheral surface of the ball rolling groove. A nut member having a spiral load rolling groove having the same lead angle,
It consists of a number of balls interposed between the load rolling grooves and the ball rolling grooves and rolling while applying a load. The orbit is configured.

Several methods have been known for forming the endless track of the ball. For example, as shown in FIGS. 18 and 19, a ball rolling groove b of a screw shaft a and a nut Between the start and end of the load region formed by the load rolling groove d of the member c, ball rolling grooves b are provided at both ends.
A ball tube f provided with a tongue piece g that protrudes inward and rolls in the ball rolling groove b in the load area, or feeds the ball e into the ball rolling groove b in the load area. And the ball e, which has exited the end of the load area, is circulated again through the ball tube f to the start end of the load area (actual opening 49-6).
No. 4672) and FIGS. 20 to 22, a ball return hole h is formed in the nut member c along the axial direction of the outer solid portion, and a gap is formed between both ends of the nut member c. Seat i
The side covers k are attached with the ball cover groove b of the screw shaft a and the nut member c by the side covers k and the spacers i.
The ball e coming out of the end of the load region formed by the load rolling groove d is inclined to guide the ball e out of the end of the load region to the outer cylindrical surface of the screw shaft a. Then, a side change method j for guiding the ball e to the ball return hole h of the nut member c is formed to form an endless track of the ball e (US Pat. No. 4,14
No. 8,226) is known.

However, in each of these methods, when the ball e moves from the end of the load area of the endless track to the no-load area, the tongue g of the ball tube f and the traveling direction of the ball e at the end of the load area. That is, the ball e collides with the side wall of the turning path j inclined from the tangential direction along the lead angle of the load rolling groove d, whereby the rolling ball e causes the ball tube f and the turning path j to form a no-load area. And is circulated again to the beginning of the load zone.

For this reason, in these conventional ball screw devices, the ball rolling in the load area is scooped up to the no-load area, or the ball is rolled in the no-load area, regardless of the method of forming the endless track of the ball. When a certain ball is fed into the load area, means for changing the traveling direction of the rolling ball is required, which necessarily impairs the smooth circulation of the ball and consequently the uniformity of the ball screw device. In this case, stable rotational motion is impaired, the life is shortened, and noise is generated.

[0006]

The inventors of the present invention have intensively studied means for fundamentally solving this problem, and as a result, they have a function of holding a large number of balls in an aligned state and rolling freely. A ball connector is formed by using a flexible connector, and the ball connector is incorporated into the endless track of the ball. A guide unit that guides and moves each ball with a connecting body that moves in the no-load area, and guides the connecting body in the direction of movement of the ball toward the load area on each of the turning paths formed at both ends of the no-load area. The present invention has been found to make it possible to smoothly transfer the ball between the load area and the no-load area of the endless track, thereby achieving a smooth circulating motion of the ball. It was.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a ball screw device of a side cover type capable of smoothly transferring a ball between a loaded area and an unloaded area of an endless track, thereby achieving a smooth circulation movement of the ball. Is to provide.

[0008]

That is, the present invention provides a screw shaft having a helical ball rolling groove on the outer peripheral surface, and a helical ball opposing the ball rolling groove of the screw shaft on the inner peripheral surface. A nut member having a loaded rolling groove and a non-loaded ball passage; and a direction attached to both ends of the nut member for forming a continuous track of the ball by communicatively connecting the loaded rolling groove and the unloaded ball passage. A pair of side lids having a turning path,
A side cover-type ball screw device comprising: a ball connected body formed by a number of balls rolling in the endless track and a connected body that connects the balls in an aligned state and rotatably holds the balls, In the no-load area of the endless track formed by the direction change path and the no-load ball path, a guide groove is formed to guide the connection body. In the no-load area, the ball is guided and moved by the connecting body in the no-load area, and at least on the load rolling groove side of each of the direction change paths in the traveling direction of the ball moving through the load rolling groove. It is a side cover type ball screw device which formed a guide part for guiding the above-mentioned connected object along.

[0009] In particular, the connecting member of the ball connecting member is
It is composed of an interposed portion interposed between the balls and a connecting portion that connects and connects the interposed portions, and the connected portion is slidably fitted in the guide groove and guided. Further, the guide portion of each direction change path is configured to be guided in the traveling direction of the ball rolling in the load rolling groove, that is, in the tangential direction along the lead angle of the load rolling groove or the ball rolling groove. This is a side cover type ball screw device.

In the present invention, the ball rolling groove formed on the outer peripheral surface of the screw shaft may be formed in a so-called circular shape having a ball rolling surface having a substantially semicircular cross section. It may be formed in a so-called gothic arch shape in which two approximately 1/4 circle arc-shaped ball rolling surfaces intersect, and the number is one or two or more. Is also good.

The nut member screwed to the screw shaft via a number of balls has a helical load rolling groove opposed to the ball rolling groove of the screw shaft on an inner peripheral surface thereof. In addition, it is only necessary to have a no-load ball passage for circulating the ball from one end of the load rolling groove to the other end.

Here, the load rolling groove may be formed in a so-called circular shape having a ball rolling surface having a substantially semicircular cross section, similarly to the ball rolling groove of the screw shaft. Also, it may be formed in a so-called Gothic arch shape in which two approximately 1/4 circular arc-shaped ball rolling surfaces intersect, and the number thereof is also 1 according to the number of ball rolling grooves. It may be an article or two or more articles.

In the non-loaded ball passage formed in the nut member, a straight ball return hole may be formed in the solid portion on the outer periphery of the nut member along the axial direction. When a flat plate mounting surface is formed on the outer peripheral solid portion, no-load ball grooves are formed on the plate mounting surface and the guide plate mounted on the plate mounting surface, respectively, and when the guide plate is mounted on the plate mounting surface, These no-load ball grooves may face each other to form a predetermined no-load ball passage.

In the present invention, in the direction change path of each side cover, the positions of the guide grooves at the load rolling groove side start end are symmetrical from the load rolling groove side start end to the no-load ball passage side end side. And the torsion and / or bending is given so that the positions of the guide grooves at the end of the no-load ball passage side are the same as each other, whereby the nut member is provided on the outer peripheral solid portion along the axial direction. A no-load ball passage composed of a straight ball return hole can be easily formed.

Here, the means for forming each side cover having such a direction change path is not particularly limited. For example, each side cover may be formed by connecting the load rolling groove of the nut member with the unloaded groove. A return piece having a direction change path communicating and connecting with the ball passage; and a lid body having a concave portion for accommodating the return piece and being fixed to both ends of a nut member. In which the first and second pieces are divided into two along the center line.

The direction change path formed on the return piece may be entirely formed on the return piece, or a part of the direction change path on the load rolling groove side may be formed on the lid body side. It may be formed so as to smoothly continue with a part of the turning path on the return piece side, but when forming a part of the turning path on the lid body side, a guiding portion is provided on the lid body side. It is good to arrange | position some or all of it, and to perform the process of the torsion and / or bending of a turning course on the return piece side. Also, the method of dividing the return piece into two along the center line of the direction changing path is not particularly limited, and is determined in consideration of workability, common use of parts, and the like.

Each of the side lids and the nut member has a positioning between a direction change path formed on each side lid side and a load rolling groove and a no-load ball path formed on the nut member side. For accuracy and simplicity, it is preferable to form a positioning boss and a recess in which the boss fits, and more preferably, it is divided into first and second pieces. A cross section of a return piece and a lid main body that accommodates the return piece constitutes a side lid, and the first and second piece pieces of the return piece project toward the nut member corresponding to the two-way turning path. A semicircular protruding piece is protruded, and a pair of protruding pieces provided on the first and second piece pieces constitute a positioning boss of the side lid, and the positioning boss is fitted on the nut member side. It is preferable to form a concave portion that fits. By forming the positioning boss and the recess in which the boss is fitted, the guide groove is twisted and / or twisted.
Or, for the direction change path of each side lid to which bending has been given, accurately position the nut member between the loaded rolling groove and the unloaded ball passage on the loaded rolling groove side and the unloaded ball passage side. Accordingly, smooth slidability of the linked body of the ball linked body can be ensured.

Further, with respect to the ball linked body incorporated in the ball endless track, the balls are linked in a chain shape by a linked body so that the balls do not collide with each other. In the no-load area, at least the linked body does not drop off each ball so that each ball can be guided and moved by the linked body moving in the no-load area in the no-load area. Thus, it is necessary to hold the roller so as to be able to roll, and for that purpose, the connecting body is constituted by an interposing portion interposed between the balls and a connecting portion communicating and connecting the interposing portions. You.

The ball connector may be incorporated into the endless track of the ball as one or more end ball connectors formed of a connector having both ends, or an endless connector. May be incorporated into the endless track of the ball as a single endless ball connection having the following.

[0020]

Embodiments of the present invention will be described below with reference to embodiments shown in the accompanying drawings.

FIG. 1 and FIG. 2 show a side cover type ball screw device of the present invention. This ball screw device is basically formed in a cylindrical shape having a screw shaft 1 having two spiral ball rolling grooves 5 on the outer peripheral surface and a through hole of the screw shaft 1 in the center. The inner circumferential surface has two spiral load rolling grooves 6 opposed to the ball rolling grooves 5, and the load rolling along the axial direction is provided at positions opposed to each other on the outer solid portion. A nut member 2 having two ball return holes (no-load ball passages) 7 for circulating balls 9 from one end of the groove 6 to the other end; A pair of side lids 3 having two directional turning paths 8 for communicating and connecting between the load rolling grooves 6 and the ball return holes 7 to form an endless track;
Load rolling grooves 6 (load area), one ball return hole 7 of the nut member 2 (no load area), and one each of the pair of side covers 3 (two total). Turnaround 8
(No-load region) and two end ball linked bodies 4 each rolling in a total of two endless tracks, each of which has a large number of balls. 9
And these balls 9 are connected to each other in a chain shape and are formed of a synthetic resin and a flexible connection body 10 having both ends. In FIG. 2, the end ball connection body 4 is schematically illustrated so that the twist of the connection body 10 can be easily understood.

In this embodiment, as shown in FIGS. 3 and 4, each of the end ball connecting members 4
Are formed in a band shape so that the disk-shaped interposition portions 11 interposed between the balls 9 and the interposition portions 11 are in contact with the balls 9 along the spherical surfaces of the balls 9, and And four belt portions (connecting portions) 12 arranged at equal intervals of 90 ° on the upper, lower, left and right sides of each ball 9,
When viewed as a whole, the intervening portion 11 has the smallest constricted shape, and the belt portion 12 connects the balls 9 in a chain shape. Are prevented from coming into contact with each other, and the interposed portion 11 and the belt portion 12 prevent each ball 9 from dropping off from the connecting body 10.

The ball-joined end piece 4 is arranged in a mold with each ball 9 as a core, a molten synthetic resin is injected into the mold to perform insert molding, and then released from the mold. Thereafter, the formed end ball connection body 4 is immersed in a mineral oil-based lubricating oil to swell the formed connection body 10 to form a gap between each ball 9 and this connection body 10, Each ball 9 can be freely rotated while being held by the connecting body 10.

Since the end ball connection body 4 has the smallest constricted shape in the interposition portion 11 of the connection body 10, it can be bent in any direction in the interposition portion 11. It is possible, for example, in FIG.
Not only can it bend and bend in the direction between two adjacent belt parts 12, it can also bend in the direction in which the belt parts 12 are present. Thus, the balls 9 can be securely held so that they do not fall off even if these twists or bends are given.

In this embodiment, the screw shaft 1 has
An escape groove 5a is formed along the deepest portion of the ball rolling groove 5 so as to slidably accommodate the belt portion 12 of the connecting body 10 constituting the above-described end ball connecting body 4 (FIG. 15A).
To (e)).

The nut member 2 is shown in FIGS.
As shown in FIG. 1, a flange portion 13 for fixing the nut member 2 to a movable body such as a table is projected from an outer peripheral surface thereof, and faces the ball rolling groove 5 of the screw shaft 1. The spiral load rolling groove 6 is formed in a Gothic arch shape where two ball rolling surfaces intersect, and the belt portion 12 of the ended ball linked body 1 is slidably accommodated in the deepest portion of the groove. A guide groove is formed in the ball return hole 7 so that the four belt portions 12 of the end ball linked body 1 are slidably fitted to guide the linked body 10. A groove 15 is formed. In FIG. 5,
Reference numeral 16 denotes a bolt mounting hole formed in the flange portion 13, and reference numeral 17 denotes a tap hole into which a mounting screw for mounting the side cover 3 is screwed.

Next, the side covers 3 attached to both ends of the nut member 2 are formed in a donut shape having a through hole corresponding to the through hole of the nut member 2 at the center as shown in FIGS. A pair of return pieces 18 having a large part of the direction change path 8 for communicating between the load rolling groove 6 of the nut member 2 and the ball return hole 7 and a substantially fan accommodating these return pieces 18. And a lid body 20 having a part on the load rolling groove 6 side of the direction changing path 8 and being fixed to both ends of the nut member 2. First and second piece pieces 21a, 21b divided along the center line of the turning path 8 so as to divide the turning path 8 into two.
It is composed of

The direction change path 8 of each return piece 18 is linearly continuous with the load rolling groove 6 of the nut member 2 in the tangential direction along the lead angle of the load rolling groove 6. A guiding portion 8c is formed as a region, and a connecting body 10 holding a ball 9 that has escaped from a load region formed by the load rolling groove 6 of the nut member 2 is connected to the lead angle of the load rolling groove 6 by the guiding portion 8c. Is guided substantially linearly in the tangential direction of the ball 9 so that each ball 9 is guided by the guiding portion 8c.
, The ball 9 is guided along the traveling direction of the ball 9 rolling in the load rolling groove 6.

In this embodiment, a part of the guide portion 8c of the direction change path 8 is formed on the lid body 20 side, and is continuous with the remaining portion of the guide portion 8c formed on the return piece 18 side. The twisting and bending of the direction changing path 8 is performed on the return piece 18 side, and the twisting and bending processing allows the direction changing path 8 of the pair of side lids 4 to be formed.
The position of the guide groove 15 at the start end of the load rolling groove 6 is symmetrical from the start end of the load rolling groove 6 to the end of the ball return hole 7, and the guide groove is located at the end of the ball return hole 7. The positions of 15 are the same.

In this embodiment, the first and second piece pieces 21a and 21b constituting the return piece 18 are described.
As shown in FIGS. 9 to 11, the pieces 21 a and 21 b are made of metal such as brass so as to fit in the concave portion 19 of the lid body 20 in a state of being overlapped with each other. Formed by cutting, concave grooves 8a and 8b each having a substantially semicircular cross section obtained by dividing the direction changing path 8 into two along the guide grooves 15 opposed to each other are formed on each joint surface. In addition, each of the concave grooves 8a and 8b has a guide groove 1 divided into two along both side edges.
5a and 15b are formed, and when the first and second piece pieces 21a and 21b are overlapped on their joint surfaces, the direction changing path 8 of the return piece 18 is completed.

The first and second piece pieces 21a, 21a
1b, projecting pieces 22a and 22b having a semicircular cross-section projecting toward the nut member 2 corresponding to the two divided turning paths 8
When the return piece 18 formed by overlapping the first piece piece 21a and the second piece piece 21b on the joint surface thereof is incorporated into the concave portion 19 of the lid body 20, these projecting pieces are provided. The positioning bosses 22 of the return piece 18 formed by combining 22a and 22b project from the inner surface side of the completed side cover 3 (see FIGS. 7 and 8), and both end portions of the nut member 2 The positioning hole 23 (see FIGS. 5 and 6) formed on the peripheral edge of the ball return hole 7 that is open to the outside.

In this embodiment, the load rolling groove 6 and the ball return hole 7 of the nut member 2 and the direction change path 8 of the side cover 3 attached to both ends of the nut member 2 are incorporated into each endless track. As shown in FIG. 12 and FIG. 13, the phased state of the four belt portions 12 of the linked body 10 is 9
It is incorporated by being shifted by 0 °, so that the degree of twisting and bending that needs to be performed in the turning path 8 is reduced, and the endless ball link 4 can be circulated more smoothly in the endless track. Has become. 12 and 13.
In the figure, the end ball connection body 4 is schematically drawn so that the twist of the connection body 10 can be easily understood.

FIGS. 14 and 15 illustrate the movement of the linked ball body 4 in the guiding portion 8c of the direction change path 8. FIG. (A) to (f) of FIG.
4 shows a cross section perpendicular to the rolling direction of the ball corresponding to positions a to f of each ball shown in FIG.

At the position a in FIG. 14, the balls 9 of the end ball linked body 4 have the ball rolling grooves 6 of the screw shaft 1 and the load rolling grooves 6 of the nut member 2 as shown in FIG. Rolling while applying a load between
In FIG. 15B, the ball 9 escapes from the load area defined by the load rolling groove 6 and
, And moves tangentially along the lead angle of the load rolling groove 6, and separates from the ball rolling groove 6 of the screw shaft 1 and enters the direction change path 8. At this time, each ball 9 is guided by the connecting body 10 of the end ball connecting body 4 moving from the load rolling groove 6 into the direction change path 8 from the moment when the ball 9 escapes from the load area of the load rolling groove 6. Will be.

Further, during the transition from the position c to the position e via the position d in FIG.
Is further moved in the tangential direction along the lead angle of the screw shaft 1 and further away from the ball rolling groove 6 of the screw shaft 1, and is located between the screw shaft 1 and the nut member 2 in the load area of the endless track. Belt 1 of connector 10 constituting ball connector 4
2 are guided in opposing guide grooves 15 respectively formed in the first and second piece pieces 21a and 21b constituting the return piece 18, whereby the ball 9 is increasingly rolled on the screw shaft 1. At position f in FIG. 14, away from the groove 6, the ball 9 is completely guided into the turning path 8.

The end ball linking body 4 is given a predetermined twist and bend from the position f to the exit of the turning path 8, and at the exit of the turning path 8, the four Are located diagonally up and down on the left and right. In addition, the guide groove 15 of each ball return hole 7 formed along the axial direction in the solid portion on the outer periphery of the nut member 2
Is formed at the same position as the end ball connecting body 4 from the direction changing path 8 side to the ball return hole 7 side or the ball return hole 7
From the side to the direction changing path 8 side.

Next, FIGS. 16 and 17 show a modification of the end ball connecting member 4. Unlike the end ball connecting members 4 shown in FIGS. Are abutted along the spherical surface of each ball 9.
In addition, each ball 9
Two belt portions 12 are provided at positions orthogonal to the holding pieces 11a so as to be in contact with the respective balls 9 along the spherical surface.

Each of the holding pieces 11a is provided with a belt portion 12 that is guided along the guide groove (not shown) in the endless track when the end ball connection body 4 is incorporated in the endless track. The protruding portion 11b located on the outer peripheral side of the endless track is formed longer than the protruding portion 11c located on the inner peripheral side, and the ended ball connector 4 is formed along a plane connecting the two belt portions 12. When curved toward the inner circumference of the endless track,
The protrusions 11c are formed so that the tips of the adjacent protrusions 11c do not interfere with each other.

In the case of using the ball linked body 4 of this modified example, the belt portion 12 of the linked body 10 is configured to pass through the gap between the screw shaft and the nut member, so that the screw shaft There is no need to form a clearance groove for slidably housing the belt portion 12 in the ball rolling groove or the load rolling groove of the nut member constituting the load area of the ball endless track,
Processing of these ball rolling grooves and load rolling grooves becomes easier.

Even in the case of using the ball linked body 4 of this modified example, the direction formed in the unloaded ball passage of the nut member and the side lids at both ends of the nut member constituting the no-load area in the ball endless track. A guide groove is formed on the turning path so as to slidably guide the belt portion 12 of the connecting body 10. On the turning path, the load rolling is performed from the load rolling groove side starting end to the no-load ball path side end. Necessary twisting and / or bending processing is performed so that the position of the guide groove at the groove-side start end is symmetrical and the position of the guide groove at the end of the no-load ball passage is the same.

[0041]

According to the present invention, in a ball screw device having a side cover, a ball connector in which a number of balls are held in an aligned state and rollable by a connector in the endless track, is incorporated into the endless track. In the load area, the connected body is moved by each ball, and in the no-load area, each ball is guided and moved by the connected body.In addition, a load is applied to each direction change path at both ends of the no-load area leading to the load area. A guiding section that guides the ball in the tangential direction along the traveling direction of the ball rolling in the area makes the transfer of the ball between the load area and the no-load area of the endless track extremely smooth. , Smooth circulation of the ball is achieved.

According to the third aspect of the present invention,
On the direction change path of the pair of side lids that communicate and connect between the load rolling groove of the nut member and the no-load ball passage, from the load rolling groove side starting end to the no-load ball passage side end, the load rolling groove side The position of the guide groove at the starting end is symmetrical, and
Since the guide groove is twisted and / or bent so that the position of the guide groove at the end of the no-load ball passage is the same,
The posture of the connected ball that runs on the endless track of the ball is adjusted on this turning path, whereby the balls constituting the connected ball do not interfere with each other, and smoothly move in the endless track in an aligned state. Circulate.

Further, according to the present invention described in claim 4,
Since the side lid is composed of a return piece having a direction change path and a lid body having a recess for accommodating the return piece, and the return piece is divided into two along the center line of the direction change path, The required twist and / or bend can be imparted to the road, thereby forming an endless track unloaded area in which the ball linkage can stably circulate.

[Brief description of the drawings]

FIG. 1 is a front view showing a side cover type ball screw device according to an embodiment of the present invention.

FIG. 2 is a perspective explanatory view schematically showing a ball endless trajectory by cutting out a part of the side cover type ball screw device of FIG. 1;

FIG. 3 is an explanatory front view showing an end ball connected body incorporated in the side cover type ball screw device of FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a front view showing a nut member of the side cover type ball screw device of FIG. 1;

6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is an inner rear side view showing a side cover of the side cover type ball screw device of FIG. 1;

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a perspective explanatory view of the side cover of FIG. 7 as viewed from the inner surface side, and is a view in which a second piece of one return piece is omitted.

FIG. 10 is an explanatory front view showing first and second pieces of the return piece of FIG. 9;

FIG. 11 is an explanatory plan view showing first and second pieces of the return piece of FIG. 10;

FIG. 12 is an explanatory view schematically showing a relationship between a nut member and a ball endless track in the side cover type ball screw device of FIG. 1;

FIG. 13 is an explanatory diagram schematically showing a relationship between a screw shaft and a ball endless track in the side cover type ball screw device of FIG. 1;

FIG. 14 is an explanatory diagram schematically showing a relationship between a side cover and a ball endless track in the side cover type ball screw device of FIG. 1;

FIG. 15 is an explanatory sectional view schematically showing a state of a ball in an endless orbit at positions a to f in FIG. 14;

FIG. 16 is a partial front view showing a modified example of the end ball connection body incorporated in the side cover type ball screw device.

FIG. 17 is a sectional view taken along the line XVII-XVII in FIG. 16;

FIG. 18 is a plan view showing a conventional ball screw device.

FIG. 19 is an explanatory cross-sectional view of FIG. 18;

FIG. 20 is a partial sectional front view showing another conventional ball screw device.

FIG. 21 is a partial cross-sectional side view showing the nut member of FIG. 20.

FIG. 22 is an explanatory view showing an attached state of the side cover of FIG. 20;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Screw shaft, 2 ... Nut member, 3 ... Side cover, 4 ... Ended ball connection body (ball connection body), 5 ... Ball rolling groove, 5a,
Reference numeral 14: relief groove, 6: load rolling groove, 7: ball return hole (no-load ball passage), 8: turning path, 8a, 8b: concave groove, 8c: guide portion, 9: ball, 10: connection Body, 11 ...
Interposed part, 11a: holding piece (interposed part), 12: belt part (connecting part), 13: flange part, 15: guide groove, 16
... bolt mounting hole, 17 ... tap hole, 18 ... return piece, 19 ... concave part, 20 ... lid body, 21a ... first piece piece, 21b ... second piece piece, 22 ... positioning boss, 2
2a, 22b: projecting piece, 23: recess for positioning.

Claims (6)

[Claims] 1. A screw shaft having a helical ball rolling groove on an outer peripheral surface, and a non-loaded ball having a helical load rolling groove opposed to the ball rolling groove of the screw shaft on an inner peripheral surface. A nut member having a passage, a pair of side lids attached to both ends of the nut member and having a direction change path that connects and connects the load rolling groove and the no-load ball passage to form an endless track of the ball; In a side cover type ball screw device, comprising: a ball connected body formed by a number of balls rolling in the endless track and a connected body that connects the balls in an aligned state and rotatably holds the balls, In the no-load area of the endless track formed by the direction change path and the no-load ball path, a guide groove is formed to guide the connection body. As well as move your body In the no-load area, each ball is guided and moved by the above-mentioned connecting body, and at least on the load rolling groove side of each of the direction change paths, the above-mentioned connecting body moves along the traveling direction of the ball moving through the load rolling groove. A side cover type ball screw device, characterized in that a guide portion for guiding the screw is formed. 2. A direction change path of a pair of side covers, which communicates and connects between a load rolling groove of the nut member and a no-load ball passage at both ends of the nut member, the direction change path of the pair of side lids extends from the start end of the load rolling groove side. Twisting and / or bending so that the position of the guide groove at the start end on the load rolling groove side is symmetrical and the position of the guide groove at the end of the no-load ball passage side is the same toward the end of the loaded ball passage. Claim 1
4. The side cover type ball screw device according to item 1. 3. Each of the side covers has a return piece having a direction change path for connecting and connecting the load rolling groove of the nut member and the no-load ball passage, and a concave portion for accommodating the return piece, and both ends of the nut member. 3. The lid according to claim 1, wherein the return piece is composed of first and second piece pieces divided into two along the center line of the direction change path. Side cover type ball screw device. 4. The first and second piece pieces of the return piece are provided with projecting pieces having a semicircular cross section projecting toward the nut member corresponding to the two-way turning path. 4. The side cover type ball screw device according to claim 3, wherein a positioning boss for the side cover is formed by a pair of projections provided on the first and second piece pieces. 5. The ball according to any one of claims 1 to 4, wherein one or a plurality of end ball linked bodies formed of a linked body having both ends are incorporated in the endless track of the ball. Side cover type ball screw device. 6. The side cover type ball screw device according to claim 1, wherein one endless ball connecting member having an endless connecting member is incorporated in the endless track of the ball.