JPH0711310B2 - Flexible ball screw unit and telescopic support using this screw unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses a flexible ball screw unit capable of transmitting a feeding action caused by rotation of a screw or a nut member in a flexible direction, and a screw unit for the same. It is related to the retractable support column.

[Conventional technology]

A ball screw unit is used as one of the feed mechanisms in various machines and devices such as machine tools. It has a lead screw or lead screw with a rolling groove of steel balls in a screw shape, and this feed screw. The steel balls (balls) that are loosely fitted in the rolling grooves are arranged on the inner surface side of the tubular casing to circulate a row of balls in the casing.

As a device using such a ball screw unit, there is, for example, a conversion device for rotary motion and linear motion described in Japanese Utility Model Laid-Open No. 60-35956. This device loosely inserts a winding of a spiral spring formed by winding a metal wire having a circular cross section into a nut member formed of a circular tube having a spherical return path formed therein, and rotates the nut member. It is a structure for advancing and retracting the winding, and the spiral groove on the surface of this winding forms a spiral rolling path of a plurality of spherical bodies.

However, the cross-sectional shape of the spiral groove in this rotary straight-line motion converter is a very shallow V-shape in which the outer surface of the groove is curved and bulges outward, which is formed by the outer surface of the metal wire to be joined. Therefore, the sphere loosely fitted in the spiral groove is only supported by point contact at a shallow portion of the spiral groove, and therefore the winding having only such a sphere supporting structure is erected in the vertical direction. There is a possibility that the sphere may be removed due to elastic deformation of the winding or an assembly error or the like in a mode in which a vertical load is applied to the portion. Therefore, the above-mentioned rotation-linear motion conversion device is not suitable as a motion conversion mechanism that uses its winding in a vertical position.

On the other hand, in a telescopic support column of a type in which a plurality of cylinders having different diameters are sequentially inserted into a cylinder having a large diameter from a cylinder having a small diameter,
Various types of expansion and contraction drive mechanisms are used, but there is no drive mechanism having a mechanical structure that extends over the entire height of a long column.

[Problems to be Solved by the Invention]

In the conventional ball screw unit, rotation is applied to the feed screw to advance / retreat the nut member that is prevented from rotating, or rotation is applied to the nut member to advance / retreat the feed screw that is prevented from rotation. Used.

However, in this ball screw unit, since the feed screw is a rod-shaped rigid body, the forward / backward movement of the nut member and the feed screw is a linear motion in which the central axis of the feed screw and the central axis of the nut member are always on the same straight line. I can only do it.

Therefore, the conventional ball screw unit cannot be applied to a mechanism in which the direction of linear motion is changed midway or curved motion is performed by a single unit.

However, depending on the machine or device, it is often convenient if the direction of the feed movement by the ball screw unit can be changed and set to an arbitrary direction with respect to the direction of the unit.

For example, if the installation space for a long rigid feed screw cannot be secured because the space of the device is too small, if the feed screw can be installed in a bent state, the problem of the installation space can be solved, which was impossible in the past. A long-span feed screw can be realized. It is also possible to move the article along a winding path.

The present invention has been made in view of the above points, and an object thereof is to provide a ball screw unit having a flexible feed screw and a telescopic support using the unit.

[Means for Solving the Problems]

The configuration of the present invention made in order to solve the above-mentioned problems is to wind a linear material whose cross-sectional shape is processed in advance into a coil, or
Alternatively, there is provided a flexible screw shaft in which a ball-transfer groove having an arc-shaped groove cross section is formed on the outer surface of the coil by processing the cross-sectional shape after winding the linear material into the coil shape. By providing an intermediate bearing member with a centering function and a rotation prevention function in the forward and backward movement path of
It is characterized in that a flexible screw shaft adapted to hold the screw shaft in its advance / retreat path is combined with a nut member having a load ball adapted to the ball transfer groove.

The flexible screw unit described above may rotate a flexible screw shaft having a long axial length and provide a passage of a nut member that does not allow rotation of the nut member in parallel with the screw shaft to move the nut forward and backward. it can.

Next, the structure of the extendable strut using the screw unit of the present invention is a stretchable strut composed of a plurality of different-diameter cylinders in which a large-diameter cylinder is loosely inserted into a small-diameter cylinder in order. Where (a) each cylinder has a bottom, and the outer diameter of the lower end of the small-diameter cylinder is larger than the inner diameter of the upper end of the large-diameter cylinder, (b) positioned at the upper end of the column The minimum diameter of the cylinder is provided with a canopy, and the maximum diameter cylinder positioned at the lower end of the column is fixedly erected in the mechanism room. (C) The mechanism room is made by winding a linear material into a coil. A screw, a feed nut suitable for the screw, a drive for rotating the screw, and a roll for winding the flexible screw are provided. (D) The flexible screw having one end fixed to the roll is attached to the bottom of each cylinder through the feed nut. Through the hole provided in the Attached to the canopy or the bottom of the smallest diameter cylinder, (e) each cylinder has a rotation preventing structure by an engaging relationship such as a key and a key groove that are fitted to their inner and outer walls. (F) An intermediate bearing member that has a through hole for the screw shaft in the center and a detent between the inner surface of the barrel and the inner surface of each of the cylindrical members. Each bearing member is a piano wire. It is connected with a flexible connecting member such as, etc., and the connecting member of the uppermost supporting member is fixed to the upper end side of the screw or the bottom of the smallest diameter cylinder, and the connecting member of the lowermost supporting member is maximum. Providing an intermediate support member fixed to the bottom of the diameter cylinder, (g) The extension of the support column is achieved by rotating the feed nut forward and sending the flexible screw from the winding roll to push up the cylinder with the smallest diameter. , Pulling up each cylinder from the small diameter side, h) The shortened storage of the stanchions is performed by pulling down each cylinder by pulling back the flexible nut to retract the flexible screw and winding it up on the winding roll to pull down the cylinder with the smallest diameter. It is what

[Work]

The flexible ball screw unit of the present invention is a lead screw,
Alternatively, since the feed screw is formed into a flexible feed screw by winding a linear material into a coil and using the groove of the coil member as a ball transfer groove, the feed screw is bent. It can also be arranged in parts. In addition, since the screw is flexible, it can be wound into an appropriate roll.

Further, the feed screw wound on the roll is forwarded or reversely rotated on the nut side so that the screw itself is fed out from the roll or wound on the roll without rotating, Since the advancing and retreating operations can be freely performed, the feed screw can be used as an extension / contraction drive mechanism in an extendable column having a structure in which tubular bodies having different diameters are inserted.

A plurality of intermediate bearing members having a through hole for the screw shaft in the center and provided with a rotation stopping structure between the forward and backward paths are provided in the forward and backward paths of each of the feed screws, and each intermediate Since the supporting members are connected to each other by the flexible connecting strip, the screws are always arranged at appropriate intervals in the longitudinal direction of the screw as the screw moves forward and backward, and the screw is positioned at the center of the forward and backward movement path. Since it is supported, it is extremely effective in preventing buckling of a long screw shaft.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a flexible ball screw unit of the present invention. FIG. 1 is a front sectional view of an essential part, FIG. 2 is a front sectional view of an example of a screw in the unit of the present invention, and FIG. 4 and 5 are plan views showing an example of a mechanism using the unit of the present invention, FIG. 5 is a plan view of another example, and FIG.
FIG. 7 is a plan sectional view showing a structural example of the support member 8a (8b), FIG. 7 is a front sectional view of an example of a telescopic support column, and FIG. 8 is a front sectional view showing a structural example of a bottom plate.

In these figures, 1 is a steel wire 2 wound in a coil shape with each wire being in close contact with each other, and a groove 3 for ball transfer is provided on the outer periphery of the joining portion of each filament at the joining portion of each filament. It is a flexible screw shaft formed by screwing along. In the illustrated embodiment, the linear member having a circular cross section is used, but the linear member may have an appropriate sectional shape such as a trapezoid.

The ball transfer groove is formed by winding a wire on a coil and then processing the cross section of the coil into an arc shape.
If the linear material is wound into a coil, the linear material may be processed in advance such that the cross section of the groove becomes an arc shape.

Thus, the screw shaft 1 is, except for the joint portion of the linear member 2,
Although it has a so-called ball-screw-like appearance, since the linear member 2 is wound into a coil and formed on the screw shaft 1, it has flexibility in its axial direction.

Reference numeral 4 denotes a nut member screwed onto the screw shaft 1 described above.
A short cylindrical main body 5 having an opening diameter that is loosely inserted into the outer diameter of the main body 5, and is spirally arranged along the groove 3 of the screw shaft 1 on the outer peripheral surface of the main body 5 and circulated in the main body 5. And a large number of balls 6 are formed. Instead of the balls 6, a spiral string formed according to the rolling locus of the balls 6 rolling in the groove of the screw shaft 1 may be used. The material of the string is metal, plastic, or
It is made of ceramics or other composite materials.

In FIG. 1, reference numeral 51 is a flange portion provided on the outer periphery of the main body 5, and in the embodiment of FIG. 4, external teeth 51a are formed on the outer periphery of the flange portion 51. In the example, detent 51b
Is formed in. Further, in the embodiment of FIG. 4, the screw shaft 1 itself is provided with a rotation preventing function.

An example of the flexible ball screw unit of the present invention is formed by the members 1 to 6 described above.
In addition, an example of the utilization mechanism will be described.

The nut member 4 screwed via the ball 6 to the screw shaft 1 in which the linear members 2 are wound in a coil shape in close contact with each other and the ball transfer groove 3 is spirally formed on the outer surface, By rotating the nut member 4 forward or backward at a fixed position, the screw shaft 1 can be moved in either the front or rear direction. At this time, it is assumed that the screw shaft 1 is provided with a detent function that allows the screw shaft 1 to advance and retreat and does not rotate.

On the other hand, when a rotation stopping mechanism is added to the nut member 4, when the screw shaft 1 is rotated in the forward and reverse directions, the nut member 4 is advanced and retracted along the axial direction of the screw shaft 1. .

The unit of the present invention that operates as described above can be used as a feeding mechanism as shown in FIGS. 4 and 5, for example, and this point will be described next.

In FIG. 4, the main body 5 of the nut member 4 is a bearing.
The screw shaft 1 is rotatably arranged at a fixed position through 4a, a bearing, etc., and the screw shaft 1 is not rotatable within the advancing / retreating path 10 formed in the shape of a cylinder, trough, groove, etc. by a wall surface, and is freely arranged only in advancing / retreating It Here, since the outer teeth 51a are formed on the flange portion 51 of the nut member 4, the output pinion 7a of the motor 7 is meshed with the outer teeth 51a to install the motor 7. On the other hand, the screw shaft 1 is screwed through the nut member 4.

Since the screw shaft 1 threadedly inserted into the nut member 4 is flexible, even if the screw shaft 1 is arranged with its axial direction turned 90 degrees as shown in FIG.
Rotate to move back and forth. Reference numerals 8a and 8b denote intermediate support members for the flexible screw shaft 1 arranged in the turn portion, which secures the shaft center in the forward / backward movement path 10 of the screw shaft 1.
In order to support the buckling load applied to, the screw shaft 1 is installed in the advancing / retreating path 10 so that the screw shaft 1 can be supported while rotating at a fixed position by an engaging structure similar to the nut member 4.

The support members 8a and 8b may have a structure as shown in FIG. That is, in FIG. 6, 81 is a nut member screwed onto the screw shaft 1, and 82 is a support ring member fitted to the outer circumference of the nut member 81 via balls 82a so as to form a bearing shape, for example. When the support ring member 82 is supported by the wall surface W or the like, the screw shaft 1 moving forward and backward is fixed to the nut member.
81 is supported by rotating in the ring member 82,
The screw shaft 1 is held at the center on the advance / retreat path.

Further, the intermediate support members 8a, 8b may have a structure in which only the hole through which the screw shaft 1 penetrates is provided in the central part and the intermediate support members themselves do not rotate.

Therefore, while fixing a member to be moved forward and backward to the screw shaft 1 of the mechanism shown in FIG. 4, and an appropriate supported member 9 to be transferred in FIG. 4, at a proper position on the tip side 1a of the screw shaft 1,
By arranging in the forward / backward path 10 with a detent,
This member 9 can be moved forward and backward together with the forward and backward movement of the screw shaft 1. Since the amount of advance / retreat of the member 9 is determined by the total length of the screw shaft 1, the rear end side of the screw shaft 1 formed to be long.
By winding 1b around an appropriate winding wheel or the like so that it can be freely wound and unwound, the member 9 can be arbitrarily advanced and retracted at a considerable distance, and can be positioned at an arbitrary position. It will be possible.

In the above embodiment, since the screw shaft 1 is flexible and hollow, a flexible core material may be inserted therein. As a result, the buckling strength of the screw shaft 1 can be increased.

In the flexible ball screw unit of the present invention which can be freely wound and unwound as described above, the screw shaft 1 is moved forward and backward along the path.
Since it can be held in the center of 10 and can be freely advanced and retracted, it can be used as an expansion and contraction drive mechanism of an expandable support column as shown in FIG. 7, for example. Next, an example of this extendable column and an example of its drive mechanism will be described with reference to FIG.

In FIG. 7, reference numerals 11 to 16 represent cylindrical bodies having different diameters, respectively.
It is a plurality of cylindrical bodies with different diameters, which are loosely inserted into the cylindrical body.

The cylindrical bodies 11 to 16 respectively have bottom plates 11a to 16a, and the outer diameters of the lower ends 11b to 15b of the small diameter side cylinders are larger than the inner diameters of the upper ends 12c to 16c of the large diameter side cylinders. Forming big,
The small-diameter cylindrical body is prevented from coming out of the large-diameter cylindrical body. Incidentally, 11d is a canopy member attached to the upper end 11c of the smallest diameter cylindrical body 11, and 17 is a mechanism chamber integrally formed with the bottom portion 16a side of the largest diameter cylindrical body 16, and the lower part is omitted in FIG. ing. When each cylindrical body is a cylindrical body, a detent structure having an engaging relationship such as a key and a key groove is provided between the inner and outer surfaces of each cylindrical body. When each cylinder has a polygonal shape, each cylinder itself has such a detent function.

With the above configuration, each of the cylindrical bodies 11 to 16 is such that the small-diameter side cylindrical body is sequentially loosely inserted into the large-diameter side cylindrical body, and when the small-diameter cylindrical body 11 is pulled up in this state, At its lower end, the upper end of the large-diameter cylindrical body 12 is hooked, and the small-diameter cylindrical bodies 12 ... Are successively pulled up with the large-diameter cylindrical bodies 13 ...

Therefore, in the present invention, the screw shaft 1 of the flexible ball screw unit of the present invention is provided on the back surface of the bottom plate 11a of the cylindrical body 11 having the smallest diameter.
Of the other cylindrical body 12 to 16 and the bottom end 12a to 16a of the other cylindrical body 12 to 16 through which the screw shaft 1 penetrates.
16e are provided to allow the screw shaft 1 to be inserted while supporting the screw shaft 1 so as to be positioned at the center of each cylindrical body.
The latter half side of is wound around the winding roll 18 in the mechanism room 17.

The supporting members 12e to 16e are formed as shown in FIG. 8 as an example, similar to the structure of the supporting members 8a and 8b in the previous embodiment (see FIG. 6).

That is, in FIG. 8, 12a to 16a are bottom plates, and 12f to 16f are nut members screwed on the screw shaft 1.
.About.16f are rotatably mounted in holes 12h to 16h opened in the bottom plates 12a to 16a with balls 12g to 16g on the outer periphery thereof. The units 12f to 16f screwed onto the screw shaft 1 are
It is desirable to use a ball nut structure. Further, a support member having the same structure as that of the above-mentioned example is provided also in a portion of the mechanism chamber 17 where the screw shaft 1 is inserted.

It is also possible to employ a simple structure in which the bottom plates 12a to 16a are not provided with the support members as shown in FIG. 8 and a hole through which the screw shaft penetrates is provided in the center.

Further, the nut shafts 12f to 16f and the screw shaft support members 12d to 16d having the same structure as the bottom plates 12a to 16a rotatably holding the nut shafts 12g to 16g are vertically moved inside the respective cylindrical bodies 12 to 16. It may be inserted as much as possible. Also in this case, the supporting member may be of a simple structure having only a hole through which the screw shaft passes. This is because the screw shaft 1 is supported also in the middle portion of each of the cylindrical bodies 12 to 16. Support parts 12e to 16e of the bottom plates 12a to 16a, or these and the screw shaft support member 12 described above.
By d to 16d, the screw shaft 1 is held at the center in the forward and backward movement path of the screw shaft formed by each cylindrical body, so that the bending and buckling of the screw shaft 1 can be prevented.

On the other hand, the nut member 4 is rotatably held at that position inside the mechanism chamber 17. The outer periphery of the flange portion 51 of the nut member 4 is formed with teeth 51c of the worm wheel here, and the worm wheel has a motor 7
Worm 7c attached to the output shaft of is engaged.
In FIG. 7, 19 is a pair of support rolls supporting the rising portion of the flexible screw shaft, and two or more sets of these rolls may be provided at appropriate positions.

As a power transmission mechanism for rotating the nut member 4, various methods other than the worm and the worm wheel can of course be used.

In the above configuration, when the cylinders 11 to 16 are in the states shown in FIGS. 7A and 7B, the motor 7 is rotated in the normal direction, the worm 7c and the worm wheel 51c are radiated, and the rotation thereof is transmitted to the nut member 4. The rotation of the nut member 4 raises the upper end side 1a of the screw shaft 1.

This rise causes the cylindrical body 11 of the smallest diameter to rise inside the large-diameter cylindrical body 12, and when the lower end of the small-diameter cylindrical body 11 reaches the upper end of the large-diameter cylindrical body 12, the large-diameter cylindrical body from this position. Ascending along with 12, the cylinders 11, 14 ... on the large diameter side are successively lifted by the cylinder 11 which continues to be lifted, and extension standing as pillars is performed.

Here, the screw shaft 1 is raised in a vertical posture, and is supported by the support members 12e to 16e of the bottom plates 12a to 16a of the cylindrical bodies 12 to 16 and the screw shaft support members 12d to 16d at a plurality of intermediate positions. Therefore, not only it has sufficient strength against vertical load, but also exhibits sufficient strength against lateral load in cooperation with the cylindrical bodies 11 to 16. Moreover, even when a vertical load is applied, the screw shaft is held in the center of the forward / backward path and moved back and forth, and further in this state,
The screw shaft 1 is the worm wheel 51b of the nut member 4.
Since the screw shaft 1 is held in the so-called locked state by the engagement of the worm 7b with the worm 7b, the screw shaft 1 does not drop by itself.

The retracted storage of the column by the extended cylinders 11 to 16 causes the nut member 4 to rotate in the direction opposite to the upward direction, and
The tip side 1a that has been fed out is wound around a roll 18 so that the small-diameter cylindrical bodies 11 to 15 are pulled back and stored in the large-diameter cylindrical bodies 12 to 16.

As described above, the flexible ball screw shaft unit of the present invention is useful as a drive mechanism for expanding and contracting a telescopic support column of a type in which a plurality of different-diameter cylindrical bodies are accommodated in the large-diameter side cylindrical body in order of the small-diameter side. It is a thing.

Here, as described above, when the cylindrical body is a cylindrical body, it is desirable to prevent the inner and outer surfaces of each cylindrical body from being rotated by the relationship between the key and the key groove.

Further, when each of the cylinders is extended and erected on the support column, the outer surface of the lower end and the inner surface of the upper end of each cylinder may be tapered in order to tightly connect the cylinders to each other.

Next, as shown in FIG. 5, a detent 51b is formed on the flange portion 51 of the nut member 4 so that the flange portion 51 of the nut member 4 cannot rotate with respect to the slide guide provided as the advance / retreat path 10. The flexible screw shaft 1 is screwed into the nut member 4 while the rear end 1b of the screw shaft 1 is screwed onto the output shaft 7b of the motor 7 via the coupling 1c. It is an example of a feeding mechanism configured by being connected.

In the example of FIG. 5 as well, for convenience of explanation, the screw shaft 1 is arranged in a posture in which it is turned by 90 degrees as an example.

In the mechanism shown in FIG. 5, the nut member 4 is arbitrarily moved along the slide guide formed as the advancing / retreating path 10 by the action of the screw shaft 1 rotated by the motor 7 by rotating the motor 7 in the forward and reverse directions. Move forward and backward.

〔The invention's effect〕

As described above, in the mechanism of the present invention, since the screw shaft of the ball screw unit is formed to be flexible, there are the following unique effects.

Since the screw shaft is flexible, even if the screw shaft is laid out with an appropriate radius and bending angle, it can be screwed with the nut member in its straight line portion and can be rotated from the outside in this state. The flexible screw shaft can freely move back and forth in response to rotation of the nut, or the nut member can be freely moved back and forth by rotating this screw shaft from the outside. In addition to being able to utilize the advantage of a flexible screw shaft that the ball screw unit can be applied even in a space where it cannot be installed, in the present invention, the forward and backward movement path of the screw shaft has a through hole of the screw shaft at the center, A plurality of intermediate bearing members provided with a rotation stopping structure are provided on the outer periphery and a detent structure, and each intermediate bearing member is connected to each other by a flexible connecting strip. Thus, as the screw advances and retreats, the screws are always arranged at appropriate intervals in the length direction of the screw, and the screw is positioned and supported at the center of the advancing and retracting path, which is extremely effective in preventing buckling of a long screw shaft. Target.

Therefore, the ball screw unit of the present invention described above has a flexible screw shaft and is provided with a buckling prevention structure at the time of extension. By using it as a drive mechanism for the expansion and contraction operation of the retractable support column of the type housed in, it is extremely useful in constructing an expansion and contraction column having both smooth expansion and contraction operation and high strength.

[Brief description of drawings]

FIG. 1 shows an example of a flexible ball screw unit of the present invention. FIG. 1 is a front sectional view of an essential part, FIG. 2 is a front sectional view of an example of a screw in the unit of the present invention, and FIG. 4 and 5 are plan views showing an example of a mechanism using the unit of the present invention, FIG. 5 is a plan view of another example, and FIG.
FIG. 7 is a plan sectional view showing a structural example of the support member 8a (8b), FIG. 7 is a front sectional view of an example of a telescopic support column, and FIG. 8 is a front sectional view showing a structural example of a bottom plate. 1 ... Screw shaft, 2 ... Linear material, 3 ... Ball transfer groove, 4
...... Nut member, 6 ... Ball, 7 ... Motor, 8a, 8b
…… Bearing member, 11 to 16 …… Cylinders with different diameters, 11a to 16a
...... Bottom plate of each cylinder, 11b to 16b …… Lower end of each cylinder, 11
c to 16c …… The upper end of each cylinder, 17 …… Mechanism room, 12e to 16e…
... Supporting member

Claims (8)

[Claims] Claim: What is claimed is: 1. A linear material, the cross-section of which has been processed in advance, is wound into a coil, or the wire is wound into a coil and then the cross-sectional shape is processed to form a strip on the outer surface of the coil. A flexible screw shaft having a ball transfer groove whose groove cross section is arcuate, wherein the screw shaft is provided with an intermediate bearing member having a centering function and a rotation preventing function in the forward / backward movement path of the screw shaft. A flexible ball screw unit characterized by combining a flexible screw shaft adapted to be held in a forward / backward path and a nut member having a load ball adapted to the ball transfer groove. 2. The flexible screw shaft comprises a plurality of linear members.
The flexible ball screw unit according to claim 1, wherein the flexible ball screw unit is wound in a coil shape and has a plurality of ball transfer grooves. 3. The flexible ball screw unit according to claim 1 or 2, further comprising a roll for winding a flexible screw shaft having a long shaft length, wherein a feed span of the screw shaft is increased by rotation of a nut. 4. A flexible screw shaft having a long axial length is rotated, and a passage of a nut member that does not allow rotation of the nut member is provided in parallel with the screw shaft so that the nut member is advanced and retracted along the screw shaft. The flexible ball screw unit according to claim 1. 5. A flexible screw shaft which can be moved back and forth in a forward / backward movement path by rotating a nut member, has a through hole for the screw shaft in the central portion, and has a rotation stopping structure on the outer periphery between the flexible screw shaft and the forward / backward movement path. The two or more intermediate bearing members provided are mutually connected under flexible connection conditions, and the leading end side of the connecting strip is connected to the tip of the screw shaft, and the rear end side of the connecting strip is moved back and forth. The flexible ball screw unit according to any one of claims 1 to 3, wherein the flexible ball screw unit is connected to each of the paths and is inserted into the screw shaft. 6. The flexible ball screw unit according to claim 5, wherein the advancing / retreating path has a tubular shape, a gutter shape, or a tunnel shape, and at least the tip of the flexible screw shaft is freely held only along the advancing / retreating path. . 7. The flexible ball screw unit according to claim 5, wherein the forward / backward path is formed by a telescopic type telescopic tube. 8. A telescopic support column comprising a plurality of cylindrical bodies of different diameters, in which a large-diameter cylindrical body is loosely inserted into a small-diameter cylindrical body in sequence, and (a) each cylindrical body has a bottom. In addition, the outer diameter of the lower end of the small-diameter tubular body is formed larger than the inner diameter of the upper end of the large-diameter tubular body, and (b) the canopy is provided on the minimum-diameter tubular body positioned at the upper end of the column, A cylindrical body with the maximum diameter positioned at the lower end should be fixedly erected in the mechanism chamber. (3) A flexible screw formed by winding a linear material into a coil in the mechanism chamber, a feed nut that fits the screw, and a rotating nut. And a roll for winding the flexible screw are provided. (D) The flexible screw having one end fixed to the roll penetrates the hole provided at the bottom of each cylinder through the feed nut, and the other end is a strut. Mounted on the canopy or bottom of the smallest diameter cylinder that is located at the top of the (E) Each cylinder is provided with a rotation prevention structure by an engaging relationship such as a key and a key groove that are fitted to their inner and outer walls, (f) Each cylinder has a center An intermediate bearing member having a through hole for the screw shaft and formed with a detent between the inner surface of each cylinder and each cylindrical inner surface, wherein each bearing member is connected by a flexible connecting member such as a piano wire, An intermediate bearing member in which the connecting member of the uppermost supporting member is fixed to the upper end side of the screw or the bottom portion of the smallest diameter cylinder, and the connecting member of the lowermost supporting member is fixed to the bottom portion of the largest diameter cylinder. (G) Stretching and erecting the column must be performed by pulling each cylinder from the small diameter side by rotating the feed nut forward, sending out the flexible screw from the winding roll and pushing up the cylinder with the smallest diameter. , (H) For shortened storage of the column, rotate the feed nut in the reverse direction. Telescopic strut so by pulling the minimum diameter of the cylindrical body by winding the winding roll pulled back flexible screws, to perform the cylindrical body and 引降, characterized.