JPS6039496B2 - Mobile object feeding device for machine tools, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a feeding device for a moving body such as a table of a machine tool, and particularly for a machine tool etc. that requires precision movement such as a table using a static pressure gas guide surface. This invention relates to a moving object feeding device.

In conventional general machine tools, a static pressure guide surface using lubricating oil was used for the table guide surface, and the table was moved by a widely known feed screw mechanism. In contrast, in recent years, machines for ultra-precision machining have begun to employ static pressure gas guide surfaces as guide surfaces for movable objects such as tables (hereinafter referred to as tables).
Static pressure gas guide surfaces are more easily affected by external forces than those using lubricating oil. Therefore, as in the past, a feed nut is fixed on the table side, and a feed screw provided on the guide rail side that guides the table is used. If a method is adopted in which the table is moved using a so-called general feed screw mechanism that engages directly with the feed nut, vibration transmitted to the feed screw from the motor etc. and eccentricity due to slight bending of the feed screw will be transmitted through the feed nut. The problem is that the vibration is transmitted to the table, causing the table to vibrate or meander under the influence of the vibration. For this reason, no matter how precisely the guide surfaces la to lf are formed, the actual accuracy that can be obtained is reduced due to the negative influence from the feed nut. The same problem occurs with other guide systems such as guide surfaces, which poses a problem for ultra-precision machining.
In order to solve the above-mentioned problem, a wire or steel band plate-like member is tensioned and fixed to the table parallel to the guide surface, and the feed nut of the feed screw mechanism provided on the guide rail side is connected to the wire or band. It connects in the middle of the steel plate-like member, transmits the movement of the feed nut to the table by the tensile force of the wire or steel band plate-like member, and in a direction perpendicular to the tension direction of the wire or steel band plate-like material. This allows the table to move more precisely along the guide surface by absorbing the vibration of the feed screw and deflection due to bending.

1 to 3 showing one embodiment of the present invention will be explained below. In Fig. 1, 1 is a guide rail, and the upper part has mutually parallel guide surfaces la, lb, lc, ld, le.
, lf. A table 2 is mounted on this guide rail 1. The table 2 is provided with static pressure pockets (not shown) that constitute a pressure gas guide surface, facing each of the guide surfaces la to If, and are supplied with pressurized air from a compressed air supply source (not shown). and table 2
is supported so as to be movable along guide surfaces la to lf. Two brackets 3 are fixed to the side surfaces of the guide rail 1, and a feed screw 4 and a guide bar 5 are respectively attached to these brackets 3 so as to be parallel to each of the guide surfaces la to lf. .

A guide bar 5 is fixed to the placket 3, and a timing pulley 6 is attached to one end of the feed screw 4.
It can be rotated via a belt 7 by a motor 8 with a speed reducer that can freely rotate in forward and reverse directions. A feed nut 9 is engaged with the feed screw 4 and movably engaged with the guide bar 5.

On the other hand, on the front and rear surfaces of the table 2 in the moving direction,
A pair of tensioning devices 11a and 11b are attached, and a wire 12 such as a piano wire is tensioned and fixed between them parallel to the guide surfaces la to lf.

FIG. 2 shows an enlarged view of one tensioning device 11a, in which a support plate 14 is fixed to the front surface of the table 2 (the right end surface in FIG. 2) with bolts 13, and a support plate 14 is provided at the tip of the support plate 14. The hole 14a has a hole 15a in which the wire 12 can be inserted.
A screw shaft 15 provided with a screw shaft 15 is freely inserted. The screw shaft 15 is provided with a groove 15b extending in its longitudinal direction, and a tip protrusion 16a of a set screw 16 for preventing rotation is engaged with the groove 15b to allow the screw shaft 15 to move in the axial direction. There is. A support plate 14 is attached to the outer peripheral screw portion of the screw shaft 15.
Nuts 17a and 17b are engaged with each other in such a manner that the screw shaft 15 is fixed to the support plate 14 by these nuts 17a and 17b. wire 12
A stopper piece 18 having a tapered outer circumference is attached to both ends of the wire 12, and the stopper piece 18 is prevented from coming off by a low melting point metal 19 such as lead welded to the tip of the wire 12.

A clamping device 10 for connecting the four wires 12 and the feed nut 9 is fixed to the upper end of the feed nut 9 shown in FIG.

FIG. 3 is an enlarged exploded perspective view of the above-described holding device 10, in which a lower fixing plate 20 fixed to the upper end of the feed nut 9 is shown.
It has an upper fixing plate 22 attached thereon by four bolts (not shown), and is placed horizontally so that a part of its outer periphery protrudes from the opposing surfaces of both fixing plates 20 and 22, and is oriented perpendicular to the wire 12. The pins 21 and 23 buried therein are arranged to hold the wire 12 in the middle, preferably in the center of the tension devices 11a and 11b, in a point-contact manner.

In addition, in FIG. 3, 22a is a bolt hole, and 20a is a screw hole. 0 Next, the operation of this device will be explained.

When compressed air is supplied from a compressed air supply source (not shown) to static pressure pockets (not shown) of the table 2 facing each of the guide surfaces la to lf of the guide rail 1, the table 2 moves to the guide surfaces la, lb. The guide surfaces lc to lf are slightly floated up from the guide surfaces lc to lf, respectively, and are supported by air pressure. This pneumatic support is given a predetermined bridle, and the table 2 is provided with a guide surface la~
Even if an external force is applied in a direction perpendicular to lf, the table 2 is stably supported to some extent, but if the external force exceeds a certain value, it has the property of causing the table 2 to deflect with respect to the guide rail 1. ing. Table 2 is guide surface la, lb
When the motor 8 with a speed reducer, which is the drive source of the table 2, rotates in the floating state, the feed screw 4 rotates via the belt 7 and the timing pulley 6, and the feed nut 9 is moved along the guide bar 5. move it.

The feed nut 9 moves the table 2 via a clamping device 10 and a wire 12 which is tensioned on the side of the table 2. At this time, the wire 12 is
1b, the wire 12
, that is, the movement of the feed nut 9 in the direction along the guide surfaces la to lf is faithfully transmitted to the table 2.

On the other hand, the feed nut 9 is connected to the feed screw 4 and the guide bar 5.
is relatively long, and there is a small gap between them and the feed nut 9, so vibrations caused by the rotation of the motor 8 with a reducer may cause it to move in a direction perpendicular to the guide surfaces la to lf. If the feed screw 4 or guide bar 5 vibrates and is bent, it will move in a direction perpendicular to the guide surfaces la to lf, and the feed nut 9, that is, the table 2
The guide surface Ia~
It is difficult to completely eliminate the deflection of the feed nut 9 in the direction perpendicular to lf.

Therefore, this device has guide surfaces la to l on the side of the table 2.
Since the table 2 is connected to the feed nut 9 via the wire 12 which is tensioned and fixed parallel to f, the feed nut 9 may vibrate or move in a direction perpendicular to the direction of movement of the table 2. However, the movement of the feed nut 9 in this direction is absorbed by the bending due to the elastic deformation of the wire 12, and the external force in this direction on the table 2 is kept small.
The table 2 can be stably supported and guided by the static pressure supporting force of the guide surfaces la to lf.

Note that the degree of tension of the wire 12 is determined by the weight of the table 2,
Although it is determined by the feed speed, etc., when increasing the tension, first tighten the nut 17a shown in FIG. 2 on the clamping device 10 side.
After loosening the nut 17b on the opposite side, turn the nut 17b little by little so that the screw shaft 15 moves to the right, and when the appropriate tension is reached, firmly tighten the nut 17a that was once loosened.
The degree of tension in the wire 12 can be increased.

On the other hand, if you want to lower the tension, loosen the nut 17a, then turn the nut 17b on the opposite side in the opposite direction to move the screw shaft 15 to the left, and when the tension is moderately loosened, turn the nut 17a. o In addition, when holding the wire 12 with the clamping device 10, the wire 12 may be tightened.
The smaller the contact point between the wire 1 and the clamping member, the more
Since the deflection of 2 is easily absorbed, as shown in Figure 3, 2
It is preferable to hold it with book pins 21 and 23.

In addition, by holding the tensioned central part of the wire 12, the range in which the external force due to the bending of the wire 12 can be absorbed can be increased, and the area in which the bending of the wire 12 can absorb the external force in the direction along the guide surfaces la to lf of the table 2 can be expanded. Misalignment can be prevented. Note that in this embodiment, table 2
Wires such as piano wire are used to absorb external forces in any direction perpendicular to the direction of movement of the Alternatively, a steel band plate may be used.

Further, by providing the mounting position of the feed screw at the center of the lower surface of the table, it is possible to further reduce twisting when the table is moved.

As mentioned above, in this method, the feed nut is not directly attached to a moving body such as a table, but is attached to the table via a wire or steel band plate-shaped member that is tension-fixed to the moving body parallel to the moving direction of the moving body. As a result, the external force applied to the table from the feed nut in the direction perpendicular to the direction of movement of the table is absorbed by the elastic deformation of the wire, etc.
Therefore, the window effect of the external force on the moving body is reduced, and vibrations and vibrations of the moving body are reduced.
It becomes possible to hold the bridge and move it more precisely,
If only the guide surface is formed with high precision, the moving object can be moved with high precision even if the movement accuracy on the feed nut side is somewhat inferior. This is extremely effective in devices that require highly accurate movement, such as feeding devices.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is an enlarged sectional view of one side of the tensioning device, and FIG. 3 is an exploded enlarged perspective view of the supported device. 1... Guide rail, la~lf... Guide surface, 2.
...Table (moving body), 4...Feed screw, 5...Guide bar, 8...Motor with reducer, 9...Feed nut, 10 ...Autumn holding device,
11a, 11b... tension device, 12...
・Wire, 14... Support plate, 15... Screw shaft,
16... Set screw for rotation prevention, 17a, 17b... Nut, 18... Stopping piece, 19... Low melting point metal, 20... Lower fixing plate, 21, 23... ...Pin, 22...Top fixing plate. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a moving body feeding device for a machine tool, etc., comprising a moving body movably engaged and supported by a guide surface of a guide rail, and a feed screw mechanism provided between the moving body and the guide rail, the above-mentioned A wire or steel band plate-like member positioned parallel to the guide surface and tension-fixed to the moving body, a feed screw positioned parallel to the guide surface and provided on the guide rail side, and the same feed. A machine tool comprising: a feed nut that is engaged with a screw and is movable in parallel to the guide surface; and means for connecting an intermediate portion of the wire or steel band plate-shaped member to the feed nut. Mobile object feeding device such as.