JPH02125151A - Screw feeder - Google Patents

Abstract

PURPOSE:To eliminate backlash and transmit the rotary motion with high precision by providing rotatively exciting springs so that receiving members screwed on screw bars and having outer threads in the opposite direction to the screw bars are moved near nut members. CONSTITUTION:Receiving members 7a and 7b having outer threads 6a and 6b are brought into contact with end faces in opposite directions of a pair of nut members 4a and 4b having outer screws 3a and 3b in the opposite direction to a screw bar 2 and screwed on the screw bar 2 via rolling elements 13 and also screwed on the inner threads 8 of a screw tube member 9. One end of coil springs 10a and 10b is fitted to the screw tube member 9, the other end is fitted to the receiving members 7a and 7b respectively, and the coil springs 10a and 10b rotatively excite the receiving members 7a and 7b so that they are moved near the nut members 4a and 4b side. The backlash due to the abrasion between members brought into contact with each other is prevented, and the rotary motion can be converted into the linear motion with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ratchet feeding device that is installed in, for example, a machine tool and is capable of automatically correcting backlash during reciprocating motion.

BACKGROUND OF THE INVENTION In today's machining, we have already entered an era of actual operation in which tolerances in the thousands range are becoming a reality in order to raise the standards for machining accuracy, which requires precision. The challenge from the 100-minute period to the 1,000-year period was a battle that spanned a long period of time. Rather than 1,000-minutes, 10,000-minutes, 100,000-minutes...
..., the ideal sought by N is limitless, and the world of real numbers is infinite. The purpose is to confine this endless real number field into a closed field and control it arbitrarily.

Conventional table position feeding using ball screws and nuts uses a spacer between two nuts to reduce the backlash caused by each forward and reverse rotation of the input shaft in order to repeat linear motion. Constant preload acting on the seat! 1
111, but it cannot withstand the backlash of long-term linear motion, and the value of the knockout crash increases in proportion to time.

To solve this problem, it is first necessary to stop the machine and repeat the preload adjustment each time.

Even if the properly adjusted preload is maintained for one month, this will start from the first day of that month, and the backlash value will change with each passing day indefinitely as the shaft rotates. It becomes bigger.

To solve these problems, it is essential to develop a device that can automatically adjust the preload during rotational or linear motion without stopping it.

Problems to be Solved by the Invention An object of the present invention is to solve the above-mentioned technical problems, to prevent backlash caused by wear between members that are in contact with each other, and to
It is an object of the present invention to provide a screw feeding device capable of converting rotational motion into linear motion and transmitting the same with high precision.

Means for Solving the Problems The present invention provides a threaded rod and a threaded rod that is threaded onto the threaded zelkova at intervals in the axial direction of the threaded zelkova.
A pair of nut members having external threads facing oppositely to the threaded rods, and a receiver that abuts the end faces of the nut members in the direction away from each other, is threaded onto the threaded rod, and has external threads facing oppositely to the threaded rods. a threaded cylindrical member having an internal thread threaded onto the outer thread of the nut member and the receiving member, one end of which is attached to the receiving member, the other end of which is attached to the threaded cylindrical member, and the receiving member is proximate to the nut member; The screw feeding device is characterized in that it includes a spring that biases the screw so that a rotational force is generated in the direction.

According to the present invention, a pair of nut members having external threads in opposite directions to the threaded rod are provided, and the receiving member abuts the end faces of the nut members in the direction away from each other. This receiving member is formed with an external thread facing in the opposite direction to the threaded rod. These nut members and receiving members are screwed into the inner thread of the threaded cylinder member.

One end of a spring is attached to this threaded cylinder member, and the other end of the spring is attached to the receiving member. In such a receiving member, since the end face of the nut member is in contact with the nut member, for example, even if wear occurs between the nut member and the threaded rod, the receiving member will be held against the nut member by the spring depending on the amount of wear. The receiving member rotates in the direction of approaching, thereby keeping the receiving member elastically in contact with the end face of the nut member, so that the nut member and the threaded rod are always kept in contact with each other.

Embodiment FIG. 1 is a sectional view showing a screw feeding device 1 according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the screw feeding device 1 shown in FIG. The screw feeding device 1 has a rotating shaft ml 1
Arrow mark around A1. A threaded rod 2 that is rotationally driven in the A2 direction, and external threads 3a, 3 that are threaded on the threaded rod 2 at a distance T in the direction of the axis 21 of the threaded rod 2, and that are threaded in the opposite direction to the threaded rod 2.
A pair of substantially right cylindrical nut members 4a, 4b having a radius of
a, 5b, a pair of receiving members 7a, screwed into the threaded rod 2, and having external threads 6a, 6b facing oppositely to the threaded rod 2;
7b, nut members 4a, 4b and receiving members 7a, 7
A threaded cylindrical member 9 having an inner thread 8 screwed into the outer threads 3a, 3b; 6a, 6b, and one end of which is a receiving member 7a, 7b.
The other end is attached to the threaded cylinder member 9, and the receiving member 7a.

Tensile coil springs 10a and 10b that urge 7b to generate rotational force in a direction approaching the nut members 4a and 4b.
including.

A table 11 of, for example, a machine tool is fixed to the threaded cylinder member 9, and power from a drive motor (not shown) is transmitted to the threaded rod 2 via a speed reducer or the like. As a result, the screw rod 2 is rotationally driven in the direction of the arrow AlA2, and the screw feeding device 1 excluding the screw keyaki 2 moves in the direction of the arrows B1 and B2 along the rotation axis 11 of the screw rod 2, and the table 11
drive displacement in the same direction. Therefore, the threaded cylinder member 9 does not rotate in the same direction as the arrows Al and A2 as the threaded rod 2 rotates.

An internal thread 12 is formed on the inner peripheral surface of the nut members 4a, 4b, and the lead L of this internal thread 12 is the same as the lead of the external thread of the threaded rod 2. A large number of spherical rolling elements 13 are interposed between the threaded rod 2 and the nut member 4EL 4b, and the threaded rod 2 is rotationally driven around the axis 11 in directions of arrows Al and A2. As a result, when the threaded rod 2 rotates, for example, in the direction of arrow A1, the nut member 4 is removed from the rolling element 13 fitted into the screw hole 14.
A pressing force F1 is applied to a to move it in the direction of arrow B2. Further, a pressing force acts on the nut member 4b in the direction of arrow F2. This pressing force F2 is caused by the fact that although the nut member 4b tries to move in the same direction as the nut member 4a (arrow B2 direction), the receiving member 7b prevents the nut member 4b from moving in the arrow B2 direction. , receiving member 7
A pressing force F2 acts against the pressing force Fla that is assumed to act on the nut member 4b when the nut b is not attached. Moreover, since the outer circumferential surfaces of the nut members 4a and 4b are formed with external threads 3b in the direction opposite to the screw rotation direction of the threaded rod 2, the rotation of the threaded rod 2 in the direction of arrow A1 causes the nut members 4a, 4b to tighten. As the object tries to follow and rotate in the same direction, it further moves in the direction of arrow B2. Nut members 4a, 4b in the direction of arrow B2 like this
, the load from the table 11 etc. will act as a reaction force in the direction of arrow B1 through the threaded cylinder member 9. As a result, the thread feeding device 1 except the threaded rod 2
In order to move in the direction of arrow B2, the nut member 4a,
4b is a pressing force Fl that is larger than the reaction force from the threaded cylinder member 9 in the direction of arrow A1.

A component force in the direction of arrow B2 along the axis I11 of F2 must be generated, and therefore compressive preloads PI and P2 are generated as internal stress in the nut members 4a and 4b.

When the threaded rod 2 rotates in the direction of the arrow A1 in this manner, the nut members 4a and 4b are displaced in the direction away from each other, and the distance T becomes larger.
4b generates compression preloads PI and P2 while increasing the interval T, so that the threaded rod 2, the rolling elements 13, and the nut member 4a are constantly
, 4b, the receiving members 7a, 7b, and the threaded cylinder member 9 can always maintain a state of contact at each mutual contact surface. Thereby, backlash caused by wear of the rolling elements 13 can be reliably prevented.

End surfaces 5a of such nut members 4a, 4b.

The receiving members 7a and 7b are provided on both axially outer sides of 5b with spherical rolling elements 15 interposed therebetween. As shown in FIG. 3, the receiving members 7a and 7b include a spring spring 16a having a U-shaped cross section in which the tension coil springs 10a and 10b are housed, respectively, over the entire circumferential direction;
16b is formed. Such spring grooves 16a, 16b
One end of the springs 10a and 10b respectively housed in
Threaded holes 17al formed at both ends of the threaded cylinder member 9.

L7a2; Bolt 18 screwed into 17b1.17b2
It is locked by. The screw holes 17al, 17a2; 17bl, 17b2 into which such bolts 18 are screwed are as follows:
They are each provided symmetrically (2 in this embodiment) with respect to the central axis of the threaded cylinder member 9. Also, the tension coil spring 10a
, 10b in the circumferential direction 1 in the receiving members 7a, 7b.
Screw holes 19 provided parallel to the axis at 80 degree intervals
a1, 19a2; Locked by bolts 20 threaded into 19bl and 19b2. These screw holes 17.19
When assembling the screw feeding device 1, the receiving members 7a and 7b and the threaded cylinder member 9 are screwed together so that the positions of the receiving members 7a and 7b are shifted by 90 degrees in the circumferential direction. The spring force of the springs 10a, 10b is selected to be such that the receiving members 7a, 7b can be threaded inside the threaded cylinder member 9.

The tension coil springs 10a, 10b attached to the receiving members 7a, 7b in this manner bias the receiving member 7a so as to generate a rotational force in a direction approaching the nut member 4a. Note that if the direction of screw rotation of the threaded rod 2 is opposite to that in this embodiment, the receiving member 7b will be attached to the nut member 4b.
is biased by a spring so that a rotational force is generated in a direction approaching
This allows the nut member 4b to be pushed in.

A screw feeding device with the above configuration! In 1,
b When the screw rod 2 is rotationally driven in the direction of arrow A1 around the rotation axis 11, the rotational force is transmitted to the nut members 4a and 4b through the rolling elements 13, and the screw feeding device except the screw rod 2 ■ moves in the direction of arrow B2. When the screw feeding device 1 moves in the direction of the arrow B2, the nut member 4a receives a pressing force F through the rolling elements 13 of the screw holder 2.
1 in the direction of arrow B2, and by the rotation of the threaded rod 2 in the direction of arrow A1, it receives a rotational force in the same direction as the threaded rod 2 (arrow Al).

Since the nut member 4a is formed with an external thread 3a facing opposite to the screw rotation direction of the screw holder 2, the nut member 4a tends to spiral in the direction of arrow B2 due to the action of the rotational force from the screw rod 2, and the compression preload The state is such that p1 has been generated. Even if the rolling element 13 wears out in such a state, the pressing force F1 is always acting on the nut member 4a, so there is no gap between the threaded rod 2, the rolling element 13, and the internal thread 12 of the nut member 4a. does not occur,
Therefore, the nut member 4a is damaged by the amount that the rolling elements 13 are worn.
is spirally moved in the direction of arrow B2, and as the nut member 4a moves in the direction of arrow B2 l\, the end surface 5a moves slightly in the same direction.

When the end surface 5a moves in this way, the receiving member 7a is biased by the bow-shaped coil spring 10a to generate a rotational force in a direction approaching the horizontal member 4a, so that the end surface 5a is moved. The receiving member 7a moves by the amount moved by the arrow B2.
The rolling elements 15 are in contact with each other with the rolling elements 15 interposed therebetween. This prevents backlash of the nut member 4a.

On the other hand, as shown in FIG. 4, the nut member 4b tries to rotate in the same direction as the arrow A1 direction of the threaded rod 2 like the aforementioned nut member 4a, but the rotational moment M at the end surface 5b canceled by moving object 15,
The receiving member 7b receives an axial pressing force X from the rolling elements 15.
acts.

Due to such a pressing force
Arrow B is determined by the engagement between the internal thread 8 of the threaded cylinder member 9 and
It cannot move in two directions, and as a result, a compressive preload P2 is generated on the nut member 4b, and a pressing force F2 from the threaded rod 2 via the rolling element 13 acts on the nut member 4b. As a result, the threaded rod 2, the rolling element 13, and the nut member 4b
The nut member 4b is always kept in contact with the internal thread 12 without any gaps at each contact position, and backlash of the nut member 4b can be prevented. In such a state, even if the rolling elements 13 are worn out by rotating the threaded rod 2 in the direction of arrow A1 for a long period of time, the nut member 4
a, 4b can maintain a state in which the contact surfaces of the members are in contact with each other while increasing the interval T between them according to the amount of wear of the rolling elements 13. This does not cause backlash.

Furthermore, when the screw keyaki 2 is driven to rotate in the direction of arrow A2, the nut members 4a and 4b are rotated from the screw rod 2 in the opposite direction to the direction of rotation in the direction of arrow A1, that is, in the direction away from each other. The pressing forces Fl and F2 through the rolling elements 13 act to produce 5
A tensile preload is generated in the opposite direction to the compression preloads PI and P2 described above. As a result, a pressing force opposite to the pressing force X acts on the receiving member 7a, and the nut member 4b moves in the direction in which the end surface 5b moves away from the receiving member 7b (in the direction of arrow B1). Then, the tension coil spring 10b causes the receiving member 7b to spiral in a direction approaching the nut member 4b and move in a direction to drive the nut member 4b. Therefore, even when the threaded rod 2 is rotated in the arrow A2 direction l\, while increasing the distance 11T, the threaded rod 2 and the rolling element 13 are
The nut members 4a and 4b can maintain contact with each other at the contact position, and even if the rolling elements 13 wear out, no backlash will occur.

In the embodiments described above, a so-called ball screw structure was described in which the rotational force of the threaded rod 2 is transmitted to the nut members 4a, 4b via the rolling elements 13. Internal screw and j2 screw rod 2
It may be configured to engage with the external thread of.

Furthermore, as another embodiment of the present invention, a member 7 =t receives the thrust force from the nut members 4a and 4b by a structure other than the rolling element 15 as a thrust bearing.

7b, or the rolling element 15 may not be provided.

Effects of the Invention According to the present invention, since the nut members are pressed close to each other by the receiving member, the rotational movement of the pry bar f? Even if wear occurs between the members that come into contact with each other, no gap is created, so backlash can be prevented. This makes it possible to transmit the rotational motion of the screw holder with high precision and convert it into linear motion.

[Brief explanation of the drawing]

1I21 is a sectional view of the screw feeding device 21 according to an embodiment of the present invention, FIG. The sectional view, FIG. 4, is a diagram for explaining the operation of the receiving member 7b. 1... Screw feeding device, 2... Threaded rod, 4a, 4b.
...Nut member, 7a, 7b...Receiving member, 9...
Threaded tube member, 10a, 10b... Tension coil spring agent Patent attorney Kei Saikyo Part 1 Figure 1

Claims (1)

[Claims] A threaded rod; and a screw threaded onto the threaded rod at intervals in the axial direction of the threaded rod;
A pair of nut members having external threads facing in the opposite direction to the threaded rod; and a receiver that abuts the end faces of the nut members in the direction away from each other, is threadedly engaged with the threaded rod, and has an external thread facing in the opposite direction to the threaded rod. a threaded cylindrical member having an internal thread that engages each external thread of the nut member and the receiving member; one end attached to the receiving member and the other end attached to the threaded cylindrical member, the receiving member being close to the nut member; A screw feeding device comprising: a spring that biases the screw so that a rotational force is generated in a direction in which the screw feeder is rotated;