JPH02176242A - Rolling differential screw feed mechanism - Google Patents

Abstract

PURPOSE:To switch the feed rate of the above mechanism at a desired position so as to enable feeding of screws at different leads by providing a plurality of roller screws which have male screws with the same pitch as that of the male screw of a driving screw shaft and also different from each other in at least either one among their pitch diameters, the directions of their threads and the numbers of their threads, and also providing both a switching mechanism and a synchronous mechanism. CONSTITUTION:Two roller screws 251, 252 with respective male screws 261, 262 which have the same pitch as that of the male screw 12 of a driving screw shaft 13 and which also are different from each other in at least either one among their pitch diameters, the directions of their threads and the numbers of their threads, are provided in such a manner as each capable of rolling and rotating after rotation of the driving screw shaft 13 while in its state wherein it is capable of meshing with the male screw 12 of the driving screw shaft 13 and also actually meshes therewith. Either one of the roller screws 251, 252 is made to mesh with the male screw 12 of the driving screw shaft 13 by a switching mechanism 31, and then a synchronous mechanism 4 is also provided for synchronous rotation of the other roller screw 251, 252 so that the other roller screw is capable of meshing with the male screw 12 of the driving screw shaft 13 and then, during switching, the roller screw 251, 252 is made to correctly mesh with the driving screw shaft 13 so as to enable a smooth switching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rolling differential screw feeding mechanism that converts rotational motion of a drive screw shaft into linear motion. In particular, the present invention relates to a feeding mechanism that allows variable feeding speed.

For example, it can be used as a feeding mechanism for tables and heads of measuring machines, machine tools, etc.

[Prior Art] Conventionally, as a mechanism for converting the rotational motion of the drive shaft into linear motion, a friction roller is pressed against the circumferential surface of the drive shaft, and the axis of the drive shaft generated on the J* friction roller as the drive shaft rotates. A friction feeding mechanism that performs a feeding operation using a directional force (thrust) is known.

Among the friction feed mechanisms, the feed speed can be varied by means of a mechanism configured so that the lead angle of the friction roller pressed against the circumferential surface of the drive shaft can be varied to different angles with respect to the axis of the drive shaft, or It is known that a plurality of sets of lead squaring rollers are provided with different angles relative to the axis of the drive shaft, and these rollers are selectively pressed against the outer circumferential surface of the drive shaft.

[Problems to be Solved by the Invention] However, with any of the above-mentioned structures, a large pressing force is required to obtain frictional force, and the thrust force obtained is also small, so the fields in which they can be used are limited. was. Furthermore, it was not possible to have a large variable range of feed speed.

An object of the present invention is to solve the problems of the conventional screw feeding mechanism, to obtain a large thrust, and to change the feeding speed significantly.
The object of the present invention is to provide a rolling differential screw feeding mechanism that can smoothly perform switching at any position.

[Means for Solving the Problems] Therefore, in the present invention, a drive screw shaft having a male thread on the outer circumferential surface is rotatably provided in one of the two relatively movable members along the direction of relative movement, and A plurality of roller screws having male threads having the same pitch as the male threads of the drive screw shaft and different from each other in at least one of effective diameter, thread direction, and number of threads are engaged with the male thread of the drive screw shaft on the other of the two movable members. A switching mechanism is provided so as to be able to roll and rotate following the rotation of the drive screw shaft in the engaged state, and a switching mechanism is provided that engages any one of the roller screws with the male thread of the drive screw shaft. A synchronizing mechanism is provided for synchronously rotating the curved roller screw to a state where it can mesh with the male screw of the drive screw shaft when only one of the roller screws is meshed with the male screw of the drive screw shaft. do.

C action] When one of the roller screws is meshed with the male thread of the drive screw shaft by the switching mechanism and the drive screw shaft is rotated, the two members move relative to each other via the roller screw that does not mesh with the drive screw shaft. . At this time, when the drive screw shaft rotates, the roller gear meshed with the drive screw shaft also rotates due to friction between the two members, so the relative movement of the two members is the amount of movement due to the rotation of the drive screw shaft. It is determined not only by the amount of rotation of the roller screw, but also by the relative relationship with the amount of rotation of the roller screw.

Therefore, this point will be specifically explained using FIG. 2. As shown in FIG. 2, a movable member 6 is provided so as to be movable in the axial direction of a drive screw shaft 2 having a male thread 1 on its outer circumferential surface, and a male thread 3 that meshes with the male thread 1 at the same pitch is provided on the movable member 6. A roller screw 4 is provided to be able to roll and rotate following the rotation of the drive screw shaft 2, and when the drive screw shaft 2 is rotated by, for example, a motor 5, the movable member 6 is moved in the axial direction of the drive screw shaft 2. .

At this time, when the drive screw shaft 2 rotates, the roller screw 4 also rotates due to friction with the drive screw shaft 2, so the amount of movement of the movable member 6 is not only the amount of movement due to the rotation of the drive screw shaft 2. , is determined by the relative relationship with the amount of rotation of the roller screw 4.

Here, if the amount of movement due to the rotation of the drive screw shaft 2 and the amount of movement due to the rotation of the roller screw 4 are in the same direction, the lead of the entire mechanism (the amount of movement of the movable member 6 per one rotation of the drive screw shaft 2 ) will increase, and in the opposite direction, the overall lead of fil+ will decrease.

Now, the pitch of the male screw 1.3 is P, P, the effective diameter of the male screw l (the distance from the axis of the drive screw shaft 2 to the point where it contacts the roller screw 4) is d, and the effective diameter of the male screw 3 (the roller 2 of the distance from the axis of the screw 4 to the point where it contacts the drive screw shaft 2
1 &), and the number of threads of each of the drive screw shaft 2 and roller screw 4 is SS. However, s and S are - when the screw direction is right-handed, and - when the screw direction is left-handed.

Under this condition, the amount of movement when the drive screw shaft 2 rotates once is ps. At that time, since the roller screw 4 rotates d/D, the amount of movement due to the rotation of the roller screw 4 is d/D.
-pS. Therefore, the lead ΔX for the entire side of the machine is Δx=p (s+d/D −S)...
...(1).

Therefore, from equation (1), if a plurality of roller screws having male threads that differ in at least one of the effective diameter, thread direction, and number of threads are selectively engaged with the male thread of the drive screw shaft, feeding with different leads can be achieved. I know what I can do and what I can do.

In the present invention, a plurality of roller screws each having a male thread having the same pitch as the male thread of the drive screw shaft and different in at least one of effective diameter, thread direction, and number of threads can be engaged with the male thread of the drive screw shaft and are meshed with each other. Since these roller screws are designed to roll and rotate following the rotation of the drive screw shaft, if these roller screws are selectively engaged with the male thread of the drive screw shaft using a switching mechanism, feeding with different leads can be performed. .

For example, as shown in FIG.
Two roller screws 4+ and 42 having male threads 31 and 32 having the same pitch and different effective diameters, thread directions, and number of threads, respectively, are in a state in which they can and are meshed with the male thread 1 of the drive screw shaft 2, respectively. Let us consider a case where the drive screw shaft 2 is provided so that it can roll and rotate following the rotation of the drive screw shaft 2.

Here, the pitch P of the male thread 1 of the drive screw shaft 2 is set to P=1.
5 [nn], effective diameter d = 15 [m+n], right-hand thread 1
In other words, under the condition that s=1, the first roller screw 4. The effective diameter of the male thread 3 of the second roller screw 4 is 5 [mm], and the effective diameter D2 of the male thread 3 of the second roller screw 4 is Dz=
30 [nm], the lead Δx1 when the first roller screw 41 meshes with the male screw 1 and the lead Δx2 when the second roller screw 42 meshes with the male screw 1 are as follows from equation (1): Δx 1= 1.5 (1+15 / 5 X 1)
= 6[++m ΔX 2 = 1, 5 (1+15 / 30
1)=2.25 [city]. However, the male threads 31, 3□ have one right-handed thread, that is, S=t. Therefore, the effective diameter D of the male thread 31 of the first roller screw 41 and the male thread 32 of the second roller screw 42 is
1. By changing D2, the feed rate can be switched between coarse movement and fine movement.

In addition, under the same conditions as the pitch P, effective diameter d, thread direction, and thread number S of the male screw 1, the first roller screw 4
The effective diameter of the male thread 31.3□ of the first and second roller screws 42 is equal to each other (D, -D2=17
[nu++1) and reverse thread, that is, male thread3. 1 right-hand thread (S=1), 32 male threads 1 left-hand thread (S=-
1), the leads Δxi and Δx2 when the respective roller screws 30 and 3□ are engaged with the male screw 1 are (1
) formula, Δx, = 1.5 <1+15/17X1)≠
2.8235 [related] ΔX 2 = 1. , 5 (1+15/17
X 1 )" = 0.1764 [mm]. Therefore, even if the thread direction of the male thread 31 of the first roller screw 41 and the male thread 3 □ of the second roller screw 4 □ is changed, the feed speed is roughly It can be switched between motion and fine motion.

In addition, under the same conditions as the pitch p, effective diameter d, thread direction, and thread number S of the male screw 1, the first roller screw 4
The male threads 30.3□ of the first and second roller screws 4□ are set to have effective diameters DI, D2, and thread directions that are equal to each other (D1
= D2 = 17 [mm]) and the number of thread threads is different, that is, male thread 31 has two right-hand threads (S = 2), male thread 3
If □ is one right-handed thread (S-1), the lead Δ when each roller screw 31, 32 is engaged with the male screw 1 is
From equation (1), x1Δx2 is Δx + = 1, 5 (1+ 15 / 17
2) Center 4.1470 [mm] ΔX2 = 1.5 (1+15/17X1-)≠2.8
235[+nm]. Therefore, even if the number of threads of the male thread 31 of the first roller screw 4 and the male thread 32 of the second roller screw 4□ is changed, the feed speed can be switched between coarse movement and rapid movement.

In this way, by simply making at least one of the effective diameter, thread direction, and number of threads of the male thread of the roller screw different from each other, the feed speed can be changed significantly, and furthermore,
Since the thrust is obtained by the engagement of the drive screw shaft and the roller screw, it is possible to obtain a larger thrust than the conventional friction feed awI.

In addition, when any one roller screw is in a state in which it is engaged with the male thread of the drive screw shaft, the other roller screws are synchronously rotated in a state in which they can be engaged with the male thread of the drive screw shaft by synchronization @ side. Therefore, even when another roller screw is engaged with the drive screw shaft by the switching mechanism, the male thread of the roller screw can always be correctly engaged with the male thread of the drive screw shaft. Therefore, switching can be smoothly performed at any position.

[Example] Hereinafter, the present invention will be explained in detail based on the example shown in FIGS. 3 to 9.

In this example, the third
As shown in the figure, the table 21 is the third one for the bed 11.
It is provided so as to be movable back and forth in the left and right directions in the figure.

One side of these two relatively moving members, here the bed 1
On the 1 side, there is a drive screw shaft 13 having a male thread 12 on the outer peripheral surface.
is rotatably provided along the reciprocating direction of the table 21. For example, the male thread 12 has a pitch ρ"
1,5 [mm], effective diameter d=15 [mm], one right-handed thread, s=1. The drive screw shaft 13 has both ends connected to a bracket 14 (third
It is rotatably supported at the left end in the figure (not shown) and is rotationally driven by a motor 15 connected to one end.

On the other hand, a mounting base 22 is fixed to the table 21 side. The mounting base 22 has a pair of left and right connecting arms 23A, 2.
3B, a roller holding frame 24 is connected to the roller holding frame 24 so as to be swingable about an axis parallel to the axis of the drive screw shaft 13. As shown in FIG. Two roller screws 25 and 252 are rotatably supported parallel to the axis of the drive screw shaft 13 at equidistant positions with the rollers 25 and 24 in a horizontal position.

The outer peripheral surface of each roller screw 25+, 25□ has a pitch p.
,, p2 has the same pitch as the male thread 12 of the drive screw shaft 13 (p = P + = P2 = 1.5 [gap]), and the effective diameter, , D2 , thread direction and number of threads S, , S2. At least one external thread 26 is different from each other. ．． 26□ are formed respectively.

Here, the roller screw 25. The male thread 2 has an effective diameter D1 of 17 [mm], which is slightly larger than the effective diameter d of the male thread 12, and has the same thread direction and thread number S as the male thread 12 (S+=1).
61 is formed. The effective diameter D2 of the roller screw 25□ is equal to the effective diameter D1 of the male screw 261 (D2 =
D, = 17 between
A male thread 26□ of =1> is formed. That is, the roller screw 25252 is formed with male screws 261 and 262 that differ from each other only in the screw direction.

Therefore, by swinging the roller holding frame 24 using the upper ends of the connecting arms 23A, 23B as fulcrums, both roller screws 25.
．． 25□ can be selectively engaged with the male thread 12 of the drive screw shaft 13, and the engaged roller screw 25. ．． 25□ can be rolled and rotated following the rotation of the 11-section moving screw shaft 13. In addition, the male screw 12
, 26° 262, as shown in FIG. 5<A>, are each formed in the shape of an arcuate surface that makes point contact on each other's effective circle. In this case, as shown in Figure 5 CB>,
Male thread 12 and male thread 26. ．． Either one of 26□,
For example, male thread 26. ．． The thread shape of the 26□ may be triangular, and the thread shape of the other one, that is, the male thread 12, may be an arcuate shape that makes point contact with the oblique side of the triangle.

Further, between the mounting base 22 and the roller holding frame 24, one of the roller screws 25. ．． 6. The switching mechanism 31 is provided between the mounting base 22 and the roller holding frame 24 and on the front side. A plurality of shape memory alloys 32,
It is comprised of a plurality of shape memory alloys 33 provided between the mounting base 22 and the roller holding frame 24 and on the rear side. These shape memory alloys 32 and 33 have the property that before being energized, they are free to bend like ordinary copper wires, or that their total length is shortened by several percent when energized.

Therefore, when the shape memory alloy 32 on the front side is energized, the roller holding frame 24 swings as shown in FIG.
is engaged with. Furthermore, when the shape memory alloy 33 on the rear side is energized, the roller holding frame 24 swings as shown in FIG. Or drive screw shaft 13
is engaged with the male thread 12 of.

Further, between the mounting base 22 and the roller holding frame 24, on both side faces thereof, there are provided roller screws 25. which are engaged with the male threads 12 of the drive screw shaft 13 by the switching mechanism 31. ．． A suppression mechanism 41 is provided for pressing the drive screw shaft 13 with a constant force. suppression al1m4
1 is constituted by a pair of springs 42A, 42B that maintain the inclined state of the roller holding frame 24 when the pair of connecting arms 23A, 23I3 swing about the upper end as a fulcrum, that is, when the roller holding frame 24 is inclined. has been done.

Further, inside the roller holding frame 24, as shown in FIGS. 8 and 9, one of the roller screws 251.25□ is engaged with the male screw 12 of the drive screw shaft 13 by the switching V& mechanism 31. When the other roller screw 25. ．． 25
In the synchronized R mechanism 51 of this embodiment, a synchronized mechanism 51 is provided which synchronously rotates the double roller screw 25. ．． 25
□ Male thread 26. ．． 26□ have opposite threads, the four fR wheels 52. rotate the free roller screws that are not engaged with the male thread 12 of the drive screw shaft 13 in the opposite direction with respect to the roller screws that are engaged with the male thread 12 of the drive screw shaft 13. 53,5
4.55. In other words, double roller screw 25. ．． Gears 52 and 53 fixed to the 25□ shaft,
Intermediate gear 54. disposed between both gears 52.53.
It consists of 55. Note that if the thread directions of the roller screws are the same, the same wI mechanism will be used to rotate them in the same direction.

Next, the operation of this embodiment will be explained.

(Coarse feed) To coarsely feed the table 21 with respect to the bed 11,
Electricity is applied to the shape memory alloy 33. Then, roller holding frame 2
4 swings as shown in FIG. 7, so the male screw 26. is in mesh with the male thread 12 of the drive screw shaft 13. At this point, the power to the shape memory alloy 33 is turned off. In this state, the drive screw shaft 13 is
When the roller screw 251 is rotated, the roller screw 251 is moved as it rolls and rotates following the rotation of the drive screw shaft 13.

At this time, the effective diameter of the male thread 261 of the roller screw 251 is = 17 [fins, 1 right-hand thread (S = 1), so the roller screw 25. The lead ΔX1 when engaged with the male screw 12 is calculated from equation (1) as follows: Δx += 1, 5 (
1+ 15 / 17 X 1 ) ≠ 2.8235 [[
111! In other words, the table 21 is 2 for the bend 11.
．． Coarse movement feed can be performed with the lead of 8235 [++++n].

(Fine feed) To finely feed the table 21 with respect to the bed 11,
Electricity is applied to the shape memory alloy 32. Then, roller holding frame 2
4 swings as shown in FIG. 6, so that the male thread 262 of the roller screw 252 meshes with the male thread 12 of the drive screw shaft 13. In this state, when the drive screw shaft 13 is rotated by the motor 15, the roller screw 25□ is moved while rolling, following the rotation of the drive screw shaft 13.

At this time, the male thread 262 of the roller screw 25□ has an effective diameter D
2 = 17 [mm] Since the left-hand thread has one thread (S--1>), the thread Δx2 when the roller screw 252 is engaged with the male thread 12 is calculated as follows from equation (1): ΔX2 = 1.
5 (1+15/17x 1) average 0.1764[
n+m], that is, table 21 is 0 for bet 11.
．． Fine movement can be performed with a lead of 1764 mm.

Therefore, according to this embodiment, the male thread 1 of the drive screw shaft 13
External thread 26. with the same pitch as 26. but with different thread directions. ．． Two roller screws with 26□ 25. ．． 25
□ is provided so that it can engage with the male thread 12 of the drive screw shaft 13 and can roll and rotate following the rotation of the drive screw shaft 13 in the engaged state, and one of the roller screws 25252 is attached to the male thread 12 of the drive screw shaft 13. Since a cut lA11lI31 is provided to mesh with the
If the roller screw 261 whose thread direction is the same as that of the male thread 12 is engaged with the drive screw shaft 13 by the side 31, the roller screw 25□ whose thread direction is opposite to that of the male thread 12 is engaged with the drive screw shaft 13. If so, you can switch to fine feed.

Moreover, these feeds are performed by the drive screw shaft 13 and each roller screw 25. ．． Since this is done through meshing with 25□, a larger thrust force can be obtained compared to the conventional friction feed a sideways.

In particular, in the case of dynamic feeding, the effective diameter D of the roller screw 25 is
1 is made slightly larger than the effective diameter d of the male thread 12 of the drive screw shaft 13, that is, the effective diameter d of the male thread 12 is 15 [m
Since D I = 17 [mm] for the male screw 12, the table 21 has a lead (Δx, -28235 [mm]) that is approximately 1.9 times larger than the pinch p (=1°5 [mm]) of the male screw 12.
■Can be made to move. By the way, roller screw 25. By making the effective diameter d smaller than the effective diameter d of the male thread 12, a lead that is more than twice the pitch p of the male thread 12 can be obtained.

On the other hand, in the case of fine feed, the thread direction of the roller screw 252 is opposite to the male thread 12 of the drive screw shaft 13, and the effective diameter D2 is made slightly larger than the effective diameter d of the male thread 12. 12 effective diameter d = 15 [m]
Since D2 = 17 [l1111], the table 21 can be slightly moved with a minute lead (ΔX2 0.1764 [k]) which is much smaller than the pitch p of the male screw 12 (=1°5 [ll1m]). Can be done. In other words,
Feed speed can be changed significantly.

Furthermore, since the effective diameter D2 of the male thread 262 of the roller screw 252 is made larger than the effective diameter d of the male thread 12 of the drive screw shaft 13, the lead is larger than 0 and smaller than the pitch p of the male thread 12. In this state, due to the rotation of the drive screw shaft 13, the roller screw 25□ generates a force in the moving direction, a force trying to separate from the drive screw shaft 13, and a force in the rotation direction. If the effective diameter D2 of the roller screw 252 is smaller than the effective diameter d of the drive screw shaft 13, the rotational force will be in the opposite direction to the rotational direction of the roller screw 25□, but if the effective diameter D2 is larger than the effective diameter d, The force in the rotational direction is the roller screw 2.
Since it is in the same direction as the rotation direction of 5□, there is no tendency for it to slip, making the reed more stable.

In addition, the thread shapes of the male thread 2626□ of the roller screw 254, 252 and the male thread 12 of the drive screw shaft 13 are both arcuate, or one is triangular and the other is arcuate, so the drive screw shaft 13 and roller screw 25
0.252 can always be brought into point contact on the effective circle. If the point where the drive screw jyyu 13 and the roller screws 251, 252 change, that is, the effective diameter, changes, the lead ΔX changes from equation (1), so the drive screw l1llll 13
and roller screw 25. ．． 25□ can be always brought into point contact with the effective circle diameter, which can stabilize the lead ΔX.

In addition, since the roller screw 251.25□ rotates following the rotation of the drive screw shaft 13, in other words, the contact surfaces do not make sliding contact like a sliding screw, but roll contact, so efficiency is high and wear is avoided. It also has an excellent effect on durability.

In addition, since the switching mechanism 31 is composed of four shape memory alloys 32 and 33, it is possible to switch to coarse movement feed by energizing the shape memory alloy 33, and to fine movement feed by energizing the shape memory alloy 32. Therefore, the switching mechanism is simple.

Furthermore, since a pressing mechanism 41 is provided that presses one of the roller screws 25+, 252 that is not engaged with the male thread 12 of the drive screw shaft 13 against the drive screw shaft 13 with a constant force, the roller screw 25. ．． 2.5□ can be rolled and rotated following the rotation of the drive screw shaft 13 without backlash or slippage. Moreover, the pressure fl1M4
1 is composed of springs 42A and 42B,
It is also structurally simple.

Also, one of the roller screws 25. ．． When 25□ is engaged with the male thread 12 of the drive screw shaft 13, the roller thread 25. ．． Since the synchronous mechanism 51 is provided to synchronously rotate the roller screws 25, . When switching 25□, there is no state in which the thread of the free roller screw engages with the thread of the drive screw shaft, and the roller thread 25. ．． 25'2 can be properly engaged with the drive screw shaft 13. Therefore, switching can be smoothly performed at any position.

In the above embodiment, the effective diameter D1. of the roller screws 25+, 252. D2 - Thread direction, number of threads 5 Of the I82 threads, the thread directions are opposite to each other, but the effective diameter, D2 or the number of threads St, S2 may be different from each other.
Furthermore, the effective diameter.

D2, thread direction, thread number S, and two or more of S2 may be configured to be different from each other.

Further, the number of roller cats is not limited to two as described in the above embodiment, but may be three or more. If there are three or more, the feed speed can be changed in three or more stages.

Furthermore, the switching mechanism 31 is not limited to one using the shape memory alloy 32 or 33 described in the embodiments - and 1-.
For example, the roller holding frame 24 may be configured to swing using the magnetic force of an electromagnet or an lenoid, or
The roller holding frame 24 may be configured to swing using a cylinder.

Furthermore, if a switching R mechanism is constructed in which both roller screws 25□ and 252 are in a neutral state in which they do not mesh with the drive screw shaft 13, the table can be floated, that is, manually moved to any desired position.

Further, the pressing mechanism 41 is not limited to the springs 42A and 42B described in the above embodiment, but also includes the drive screw shaft 1.
A magnetic circuit is formed between the roller screws 25+ and 252 meshing therewith, and the magnetic force of this magnetic circuit causes the roller screws 25. 25□ and drive screw IIi! f113 to each other, and tighten the roller screw 25. ．． 25□ may be obtained so as to press the drive screw shaft 13.

Furthermore, elastic deformation of a leaf spring or the like may be used.

Further, the synchronization mechanism 51 is not limited to the one using the gears 52 to 55 described in the above embodiments, but is, for example, a roller screw 25. ．． 25□ may be directly engaged,
Alternatively, a mechanism not shown in FIG. 10 or FIG. 11 may be used. The mechanism shown in FIG.
are shifted in the axial direction and arranged in the roller holding frame 24, and each roller screw 25. ．． Teeth that interlock with each other at adjacent ends of 252! 56 and 57 are integrally formed. This has the advantage of simplifying the configuration. Also,
1FIijM shown in FIG. 11 has each roller screw 25. ．．
Five timing gears 58 and 58 are attached to the 25□ shaft, and a timing belt 60 is passed between the two timing gears 58 and 59 to rotate the I trigram.

Further, in the above embodiment, the drive screw shaft 13 is long and the roller screw 25. ．． 25□ is shortened, but the reverse is also possible. In other words, as shown in Fig. 12, the drive screw shaft 1
3 is formed short, and the roller screw 2 selectively engages with this.
5. ．． 252 may be formed to be sufficiently longer than the drive screw shaft load 3. In this way, both roller screws 2
Since the gears for synchronizing the gears 5+ and 25□ are also provided at positions that do not interfere with the drive screw shaft 13, the four gears 52, 53
．． No need to use 54.55, two gears 52.53
There are some advantages that can be achieved with

It should be noted that the present invention is not limited to the table feeding device described in the above embodiments, but may also be applied to, for example, a column or head of a machine tool, and can be used in general in a feeding mechanism of two members that move relative to each other.

[Effects of the Invention] According to the present invention, a plurality of roller screws having male threads having the same pitch as the male thread of the drive screw shaft but different in at least one of effective diameter, thread direction, and number of threads are attached to the male thread of the drive screw shaft. Since these roller screws can be engaged with each other and can roll and rotate following the rotation of the drive screw shaft in the engaged state, if these roller screws are selectively engaged with the male thread of the drive screw shaft using the switching V1 mechanism, different results can be achieved. Can be fed with a lead.

At this time, since the thrust is obtained by the engagement of the drive screw shaft and the roller screw, it is possible to obtain a larger thrust than the conventional friction feed mechanism, and the feed speed can be changed significantly. Since a synchronization mechanism is provided, switching can be performed smoothly at any position.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the present invention in detail, and FIG. 2 is a diagram for explaining its technical basis. Figures 3 to 9 show one embodiment of the present invention.
Figure 1 is a side view, Figure 4 is a side view, Figure 5 is a diagram showing the thread shape of the drive screw shaft and roller screw, Figures 6 and 7 are
The figure is a side view showing the switching state of the roller screw, FIG. 8 is a plan view showing the synchronizing mechanism, and FIG. 9 is a side view thereof. FIGS. 10 and 11 are diagrams showing different modifications of the synchronization mechanism, and FIG. 12 is a diagram showing a modification of the drive screw shaft and the roller screw. 11.21...Bed and table (two relatively movable members), 2...Male thread, 3...Drive screw shaft, 5. 252...roller screw, 6,. 26□...Male thread, 1...Switching mechanism, i-noam, P,, P2...Pitch DI, D2...Effective diameter, S,, 32...Number of threads. Figure 1 Figure 2 - aha 2 - Aa16d 31.32 - = Xi axis 41.42 - 0 - Lane hip, Pl, P2 - Bi chair d, Dl, D2 - Friendship plan S, 51.52・-To each person h・Sile diagram (A) CB) Figure Figure Figure Figure Figure Figure

Claims (1)

[Claims] (1) One of the two relatively movable members is provided with a drive screw shaft having a male thread on the outer peripheral surface so as to be rotatable along the direction of relative movement, and the other of the two relatively movable members is provided with the drive screw shaft. A plurality of roller screws having male threads having the same pitch as the male threads of the shaft and different in at least one of effective diameter, thread direction, and number of threads can be engaged with the male threads of the drive screw shaft, and in the meshed state, the drive screw shaft is rotated. A switching mechanism is provided so that any one of the roller screws can follow the male thread of the drive screw shaft and mesh with the male thread of the drive screw shaft. A rolling differential screw feeding mechanism characterized by being provided with a synchronizing mechanism that synchronously rotates another roller screw in a state where it can mesh with the male screw of the drive screw shaft when the roller screw is in a state of being meshed with the male thread of the drive screw shaft.