JPH02186157A - Ball screw shaft device - Google Patents

Abstract

PURPOSE:To achieve accurate linear movement of a ball screw shaft by providing a guiding part that has a block for a pre-load and a transfer block by which an eccentricity ring of a rotation preventing part is guided in a direction of the ball screw shaft. CONSTITUTION:When a ball screw shaft nut 6 is turned by a driving part 2, the turning of a ball screw shaft 7 is blocked by a screw shaft rotation preventing part 20 that has a whirtl-stop pin 8, and is moved in line in a direction of the shaft, and is moved to and fro in a linear direction on a tabled T through a connecting shaft 18. If a gap is generated in a fitting ridge and root between the ball screw shaft nut 6 and the ball screw shaft 7, linear movement of the ball screw shaft 7 cannot be accurately maintained. However, by means of a transfer block by which eccentricity rings 91, 92 of the rotation preventing part 20 are guided along the direction of the ball screw shaft 7, and a guiding part that has a pre-load block that is provided opposed thereto, the linear movement of the ball screw shaft 7 can be accurately maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ball screw shaft device, and particularly to a ball screw shaft device that can realize linear movement of a ball screw shaft with high precision.

(Prior Art) A ball screw shaft device is used as a drive actuator for an XYθ table used in a machine tool, etc., as shown in FIG. A straightening motion is applied to the screw shaft to accurately move a table, etc. in a desired direction.

The above-mentioned ball screw shaft device includes a drive motor at -a, a ball screw shaft nut fixed to the rotor of the drive motor, and a ball screw shaft nut that is fitted to this via a ball screw to convert rotation interlocking of the drive motor into linear motion. The tip of the ball screw shaft is connected to a table or the like.

FIG. 5 shows a schematic plan view of the ball screw shaft device mounted on the machine tool table described above, and this situation is the same in the case of the present invention. N1)1 of ball screw shaft device as actuator. , NO,2, and 3 are used to adjust the x- and Y-axis directions and the angle θ, respectively. For example, the actuator of stone 1 moves No. 2 in the X-axis direction.
．． 3 in the Y-axis direction by moving them both straight, Nαl is moved backward, and No. 3 is moved forward to change the angle θ.
51g can be trimmed.

Furthermore, in conventional ball screw shaft devices, the stator of the drive motor is generally fixed to the ball screw NAND to allow only linear movement without rotating the ball screw shaft itself. Via a ball spline outer cylinder etc. fixed to the attached motor caning,
The ball screw shaft is configured to be able to move in a linear direction along a flat surface of the shaft such as a ball spline provided at the end of the ball screw shaft.

[Problems to be Solved by the Invention] However, in the conventional general ball screw shaft device as described above, since rotation is prevented by the flat surface, there is a risk of damage between the ball, etc. and the spline on the flat surface. The driving resistance due to the sliding friction resistance is large, and the 4-sided surface is 1? It is easy to wear, and as the wear increases, the gap on the 18 dynamic friction surface increases, causing play in the linear movement, or staining or slipping with the ball on such a flat surface. Since positioning cannot be performed accurately, various problems have arisen, such as becoming a major hindrance to automation in devices that require precise actions and functions.

This invention solves the various problems pointed out in the conventional ball screw shaft device at once, and completely eliminates the friction surface, backlash in the linearization movement, stick-slip, bump, etc. The object of the present invention is to provide a ball screw shaft device equipped with a rolling guide device that enables accurate linear movement of a screw shaft with a new configuration.

Furthermore, another object of the present invention is to attach a positioning sensor for automation to the ball screw shaft of the ball screw shaft device of the above-mentioned new configuration, thereby making it possible to detect the accurate position of the ball screw shaft device, thereby making the ball screw compatible with automation. It is to provide axis AJ position.

[Means for Solving the Problems] Therefore, in the present invention, as a means for solving the above problems, a driving section having a stator and a rotor, a ball screw shaft and the rotor that are fitted and connected to each other via balls are provided. at least one pair of ball screw nuts connected to the ball screw and rotated by the drive unit; a detent pin connected to the ball screw shaft to prevent rotation of the shaft; and a locking pin connected to one end of the pin eccentrically with respect to the pin axis. a screw shaft rotation prevention part having an eccentric ring attached to the rotation prevention part; a transfer block for guiding the eccentric ring of the rotation prevention part along the axial direction of the ball screw; and a guide part having a preload block provided opposite thereto. An unusual configuration was adopted.

If the two eccentric rings attached to the anti-rotation bin are configured to have bearings fitted around their outer peripheries and to be guided by a rolling block and a preload block, a smoother guiding action can be obtained.

For example, a coil spring is used as the elastic member, but any other material having the same function, such as a thin plate spring, may be used.

Furthermore, in the present invention, as a means for solving another object of the above-mentioned problem, a reference position of the ball screw shaft is provided in the screw shaft device at a position opposite to the locking pin of the screw shaft rotation prevention part. a position detection sensor for detecting a position, and an encoder for detecting an amount of rotation of the rotor by the drive unit;
A control section is installed to link the two and automatically control the amount of movement of the ball screw shaft based on the detected amount, so that the movement of the ball screw shaft can be automatically controlled with high precision. .

The detection sensor can be a proximity switch, for example, but it can also be an optical or other type of electronic sensor.
It may also be a type switch.

[Effect]

In the ball screw shaft device according to the present invention configured as described above, the rotor connected thereto and the ball screw shaft nut are rotated by the drive section, while rotation is prevented by the rotation stop pin of the screw shaft rotation prevention section. As a result, the ball screw shaft undergoes a straightening motion along its axial direction. The rotation prevention section is guided between the preload block and the rolling surface of the rolling block of the guide section at a distance of 70 degrees to the axis of the ball screw shaft, thereby forcibly achieving accurate straightening motion. It will be done.

Furthermore, by providing a position detection sensor, an encoder, and a control unit for the ball screw shaft device, the reference position of the ball screw shaft is detected, and the amount of movement of the ball screw is detected by the encoder. Since the ball screw shaft can be accurately positioned by interlocking, extremely accurate automatic control can be achieved.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a main longitudinal sectional view of a ball screw shaft device 1 according to the present invention (including a partial side view). In this embodiment, a stamping motor 3 is used as the drive unit 2, but other types of motors may of course be used. is provided, and the rotor 3
t is connected to a ball screw shaft nut 6, which will be described later, via a coupling 4 and a nut rotating shaft 5. Reference numeral 7 denotes a ball screw shaft, which is not shown, but is fitted and connected to the ball screw shaft nut 6 through a large number of small balls fitted into its thread groove. BSB is a bearing.

A rotation stop pin 8 is attached to the ball screw shaft 7 at a position approximately ⅓ to the left in the drawing, and rotation of the rotation stop pin 8 is prevented by a method described later.

The detent pin 8 has two eccentric rings 9 at its lower end.
1.9 □ is provided, and bearings 101 and 102 are respectively fitted on the outer periphery of the screw shaft, and these form the screw shaft rotation prevention portion 20.

FIG. 2 is a sectional view taken along line 1)-n in FIG. As shown in FIG. 2, the ball screw shaft 7 is provided with a large diameter portion 7', into which the rotation stop pin 8 is inserted from below.

1), IL indicate the rolling surfaces of the preload block and the rolling block, respectively, and in particular, the preload block is provided with elastic members made of coil springs at appropriate positions (in this example, two locations). There is.

The number of elastic members may be one, and the preload blocks may be slightly out of parallel. As shown in FIG. 3, a guide section 30 is formed by these two blocks, which prevents the rotation of the ball screw shaft 7 via the rotation prevention section 20 and at the same time prevents the linearization movement of the ball screw shaft 7. It also serves to guide the screw shaft along (parallel to) its axial direction.

Above the large diameter portion 7' of the ball screw shaft 7, there are shown in FIG.
As shown in FIG. 2, position detection sensors 15 (three are shown in this embodiment, but the number is arbitrary) are provided to detect the position of the ball screw shaft 7, and A sensor metal portion 16 is provided above the large diameter portion 7'. 1 is a lead wire for the sensor.

The detent pin 8 is fixed to the large diameter portion 7' by a small screw 13 inserted into the large diameter portion 7' and pushed through a small hole 14.

17 is an end member of the casing 1°O of this ball screw shaft device, and a connecting shaft 18 passes through this end member 17.
stands out. The 6 points are connection parts with the XYθ table T, and a universal joint may be used. IS is a fixed member.

200 is an encoder, and L is a power cord to the drive section 2, which includes a control signal cord.

FIG. 4 shows the screw shaft rotation prevention part 20 shown in FIGS. 2 and 3,
FIG. 3 is a partially enlarged perspective view of the guide section 30. FIG. As previously mentioned,
Rolling surface of rolling block 1). is provided parallel to the axis of the ball screw shaft, and the rolling surface of the other preload block is also 2
Long rolling surface 1) created by appropriately adjusting the elastic force of the two elastic members 12.12. Similarly, it is desirable to provide the shaft parallel to the axis. However, if the shaft can rotate somewhat, it may be intentionally tilted to improve positioning accuracy.

Although the illustrated example shows a case where the stepping motor 3 and the encoder 200 are provided, as a method of controlling the relative rotation amount between the drive unit and the ball screw shaft 7 rotated by the drive unit, the drive unit There are various methods, such as using a servo motor and attaching an encoder to it to detect the amount of rotation and controlling the position, combining a servo motor and a linear scale, and using only a stepping motor without an encoder.

Although not shown in the example of the configuration shown in FIG. 1, a control unit is provided for the encoder 200 and the position detection sensor 15 to control the amount of movement of the ball screw shaft based on the amount detected by the encoder 200 and the position detection sensor 15. As a result, the movement of the ball screw shaft can be automatically controlled with high precision.

The operation of this embodiment configured as described above will be explained next.

Power is applied to the drive unit 2 and the rotor 3. When you rotate the
A ball screw shaft nut 6 rotates via the coupling 4 and the nut rotating shaft 5. As described above, the ball screw shaft 7 is prevented from rotating by the screw shaft rotation prevention part 20, so it does not rotate, but performs a straightening movement in the axial direction, and the connecting shaft 1
8 to move the table T forward and backward in a straight line (5th
(see also figure).

If there is a gap (backlash) between the ridges and valleys of the fitting screw between the ball screw shaft nut 6 and the ball screw shaft 7 according to this embodiment, the straight line of the ball screw shaft 7 will be affected unless some countermeasure is taken. Although the movement cannot accurately maintain linearity, by guiding the screw shaft rotation prevention section 20 in a linear direction by the guide section 30, the linear movement of the ball screw shaft 7 can be maintained accurately. The position detection sensor 15 and the encoder 200 are linked to detect the amount of movement, and the amount of movement of the ball screw shaft is controlled via the control unit, thereby making it possible to freely control the movement of the ball screw shaft with high precision. can.

〔effect〕

As described above in detail, in the present invention, since the ball screw shaft device is provided with the screw shaft rotation prevention portion and the guide portion, the linearization movement of the ball screw shaft can be accurately maintained.

Furthermore, since the position detection sensor, encoder, and control unit are attached to the ball screw shaft device, the positioning of the ball screw shaft can be precisely controlled, and automatic control becomes extremely easy. .

[Brief explanation of the drawing]

FIG. 1 is a main vertical sectional view of a preferred embodiment of the ball screw shaft device according to the present invention, FIG. 2 is an enlarged detailed sectional view of the screw shaft rotation prevention part, FIG. 3 is a detailed sectional view of the guide part, and FIG. 4 FIG. 5 is an enlarged perspective view of FIGS. 2 and 3, and FIG. 5 is a schematic explanatory diagram when the ball screw shaft device of the present invention is used as an actuator. 1...Ball screw shaft device, 2...Drive unit, 31...Stator, 3□...Rotor, 6...Ball Screw shaft nut, 7... Ball screw shaft, 7'... Large diameter part, 8... Rotation pin, 91.9□... Eccentric ring , 10,. 10. ...Bearing, 1), ...Rolling surface of preload block, 1) This...
...Rolling surface of rolling block, 12...Elastic member, 15...Position detection sensor, 16
...Sensor metal part, 18...Connection shaft, 20...Screw shaft rotation prevention part, 30...X inside, 200...
Encoder, l...Lead wire, L...
...Power cord, C...Connection part,
T...XYθ table.

Claims (3)

[Claims] (1) A drive unit having a stator and a rotor, a ball screw shaft that is fitted and connected to each other via balls, at least one pair of ball screw nuts that are connected to the rotor and rotated by the drive unit, and a ball screw shaft. a screw shaft rotation prevention part having a rotation prevention pin connected to the shaft to prevent rotation of the shaft, and an eccentric ring attached to one end of the pin in an eccentric manner with respect to the pin axis; and an eccentricity of the rotation prevention part. A ball screw shaft device comprising a rolling block that guides a ring along the ball screw shaft direction and a guide portion having a preload block provided opposite thereto. (2) The ball screw shaft according to claim 1, wherein the eccentric ring attached to the detent pin is guided by a rolling block and a preload block by fitting a bearing on the outer periphery of the eccentric ring. Device. (3) Furthermore, a position detection sensor that detects the reference position of the ball screw shaft is located at a position opposite to the locking pin of the screw shaft rotation prevention section, and an encoder that detects the amount of rotation of the rotor by the drive section, and the two are linked together. and a control unit that automatically controls the amount of movement of the ball screw shaft based on the detected amount.
3. The ball screw shaft device according to claim 1, wherein the ball screw shaft device is configured to automatically control movement of the ball screw shaft with high precision.