JPH0547339B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a feed guide mechanism used in high-precision machine tools, ultra-precision processing machines, measuring machines, etc. This invention relates to a feed guide mechanism that slides and guides a table with a guide bar.

[Background technology and its problems]

Machine tools and the like are provided with a feed guide mechanism for reciprocating a table on which a workpiece or the like is placed relative to a base. This feed guide mechanism includes a dynamic pressure guide using a precisely finished surface of the sliding part,
Static pressure guides that use oil or air, and rolling guides that use rollers or balls are used. Among these, those using dynamic pressure have excellent characteristics such as stable support of the moving body (table) and damping properties against vibrations.

However, with this dynamic pressure, when a moving object moves by a minute amount or moves at a low speed, it causes sticks and slips. There is a problem in that smooth movement is prevented due to the occurrence of friction. As a result of this stick slip, the positioning accuracy is reduced and a uniform feed rate cannot be obtained.

Therefore, Japanese Utility Model Publication No. 38-21096 is known as a solution to these inconveniences. In this system, two rotating shafts are rotatably supported in parallel to each other via bearings in the main body of the machine tool, and a driving unit that rotates them in opposite directions is connected to both rotating shafts via gears. In addition, the tool rest is movably supported by both rotating shafts, and a feeding screw rod, which is supported parallel to the rotating shafts and has a driving part, is passed through the tool rest.

Therefore, if the rotary shaft is rotated from the driving part through the gear in advance, the sliding surface between the rotary shaft and the turret can be maintained within a low friction coefficient range, and the feed rate of the turret can be reduced. Even if it is small, it prevents problems such as sticks and slips due to fluctuations in frictional resistance, regardless of the feeding direction.

However, with this device, if there is a slight bend in the rotating shaft, the engagement between the rotating shaft and the bearing may become stiff, making it difficult to move the turret smoothly and accurately. The disadvantage is that it cannot be done.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a feed guide mechanism that is less likely to cause stick slips and can move a table smoothly and accurately.

[Means and actions for solving problems]

The present invention focuses on the fact that stick slip occurs when the friction coefficient of the sliding contact between the table and the guide bar changes from the static friction coefficient when the table is at rest to the kinetic friction coefficient when the table is in motion.
This was done based on the discovery that the problem of stick and slip can be solved by constantly rotating the guide bar in the circumferential direction and keeping it in a moving state.

Specifically, in a feed guide mechanism that slides and guides a table that can reciprocate with respect to a base using a guide bar, the guide bar is rotatably supported in its circumferential direction via a bearing member, and the guide bar is A driving mechanism for rotating the guide bar is provided, grooves are formed in the guide bar along the circumferential direction at predetermined intervals in the longitudinal direction, and the bearing member is attached to the base and the lower part of the guide bar is connected to the table. It is composed of a lower bearing element having an arcuate cross section that supports substantially the entire length of the movement stroke, and an upper bearing element having an arcuate cross section that is attached to the table and slides on the upper part of the guide bar.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

1 to 3 schematically show the overall configuration of this embodiment. In these figures, a flat rectangular parallelepiped-shaped base 1 has two guide bars 2 each having a circular cross section arranged at predetermined positions along the longitudinal direction of the base. These guide bars 2, 2 have grooves 2A formed at predetermined positions along their circumferential direction (5th
(see figure), and is rotatably supported by a lower bearing metal 3 as a lower bearing element attached to the base 1. At this time, the lower bearing metal 3 is divided into a predetermined number of parts in a direction perpendicular to the axial direction and provided in the longitudinal direction of the base. In other words, the lower part of the guide bars 2, 2 is a table 11 which will be described later.
The length is sufficient to support approximately the entire length of the travel stroke.

Each guide bar 2, 2 is rotatably supported by a bearing 4 attached to the left side of the base 1 in Figs. 1 and 2, and a worm wheel 5, It is fixed at 5. These worm wheels 5, 5 are meshed with two worms 7, 7 which are attached to a shaft 6 and are twisted in opposite directions. The shaft 6 is rotatably supported by the base 1 via a bracket 8 and is connected to a motor 9 attached to the base 1. Here, the worm wheels 5, 5, the shaft 6, the worms 7, 7
A drive mechanism 10 is composed of the motor 9 and the motor 9.

A table 11 is disposed on the guide bars 2, 2, and a predetermined position on the bottom of the table 11, for example, on both left and right sides in FIGS. An upper bearing metal 12 is attached to support the guide bar 2, and the table 11 is slidably guided by the guide bar 2 and can reciprocate. Here, a bearing member 13 is composed of the upper bearing metal 12 and the lower bearing metal 3, and these upper and lower bearing metals 12, 3 have the same diameter as the guide bars 2, 2, as shown in FIG. It has an arcuate cross section and is attached to the table 11 and the base 1 at a minute distance S from each other. Further, recesses 14, 14 are formed in the upper and lower bearing metals 12, 3 in the vertical direction along the guide bar axial direction, and the guide bar 2 is connected to these bearing metals 12, 3.
2 and 3 are designed to be received just like a V block.

A nut member 15 is attached to the bottom of the table 11, and a ball screw shaft 16 is engaged with the nut member 15. This ball screw shaft 16
is rotatably supported by a bearing 17 attached to the base 1, and connected to a feed motor mechanism 18 capable of forward and reverse rotation at a position extending leftward from the bearing 17.

In such a configuration, when the motor 9 is driven, the shaft 6 and the worms 7, 7 are rotated.
Along with this, the worm wheels 5, 5 and the two guide bars 2, 2 are rotated in mutually opposite directions. At this time, the rotation speed of the motor 9 is adjusted so that the guide bars 2, 2 are rotated at a low speed.

As a result, the guide bars 2, 2 and the bearing member 13
and are always in sliding contact under the coefficient of dynamic friction.

Furthermore, when the feed motor mechanism 18 is driven, the ball screw shaft 16 is rotated in forward and reverse directions, and along with this,
The table 11 is connected to the base 1 via the nut member 15.
is moved back and forth.

According to this embodiment, the guide bar 2,
2, when the table 11 changes from a stationary state to a moving state, the coefficient of sliding friction between the guide bars 2, 2 and the bearing member 13 does not change from a static friction coefficient to a dynamic friction coefficient, so that sticks and slips are prevented. It never occurs. Therefore, the smooth movement of the table 11 is not hindered, the positioning accuracy is improved compared to the conventional one, and the feed rate is also uniform. Moreover, since two guide bars 2, 2 are provided and these are rotated in opposite directions, the horizontal direction applied to the table 11 by the rotation of the guide bars 2, 2, that is, the direction perpendicular to the reciprocating direction. Since the forces can cancel each other out, lateral displacement of the table 11 can be prevented, and from this point of view as well, smooth reciprocating of the table 11 is possible. Furthermore, since the guide bars 2, 2 have grooves 2A formed along the circumferential direction thereof, abnormal movement of the table 11 due to the rotation of the guide bars 2, 2 due to bending or the like can be prevented. That is, when the guide bars 2, 2 are lengthened in proportion to the feed stroke of the table 11, the guide bars 2, 2 may be slightly curved, but forming the grooves 2A in the guide bars 2, 2 Therefore, it adapts to the vertical load from the table 11 and obtains uniform contact, that is, it absorbs the deflection caused by the vertical load and prevents abnormal movement of the table 11 due to the rotation of the guide bars 2, 2. . Further, the bearing member 13 is divided into two parts, an upper bearing metal 12 and a lower bearing metal 3, and the lower bearing metal 3 is provided over substantially the entire length of the movement stroke of the table 11, so that it is guided by the action of the groove 2A. Correct the bending of the bars 2, 2 and move the guide bars 2, 2 to the lower bearing metal 3.
It can be supported linearly along the axial direction of the
Smooth and stable feeding is guaranteed because the table load can be stably received over almost the entire length of the table, and contact with the bearing surface can be confirmed. At this time, the upper and lower bearing metals 12,
3 has recesses 14, 14 along the axial direction of the guide bar.
Since a relief is formed, the guide bars 2, 2 are stably supported like a so-called V block.

In addition, the bearing members are upper and lower bearing metal 1.
It is not limited to 2 or 3, and may be made of a member other than metal. Furthermore, the bearing metals 12 and 3 do not have to be composed of a plurality of parts divided in a direction orthogonal to the axial direction, but may be composed of one piece each. However, if the bearing metal 1 is composed of a plurality of bearing metals as in the above embodiment,
The machining accuracy of the arcuate surfaces 2 and 3 can be improved, and reliable guidance by the guide bars 2 and 2 can be performed. Further, the number of guide bars 2 is not limited to two, and may be one or three or more. At this time, if a plurality of guide bars 2 are provided and half of them are rotated in the opposite direction to the remaining guide bars, lateral movement of the table 11 can be sufficiently prevented. Furthermore, the bearing member 13 does not necessarily need to have the recess 14 formed therein. Further, the drive mechanism 10 includes worm wheels 5, 5,
The structure is not limited to the structure provided with the worms 7, 7, but may be provided with a chain, a sprocket, or a motor directly connected to the guide bar 2, for example.

〔Effect of the invention〕

According to the present invention as described above, even when a stationary table is moved relative to the base, stick slips are less likely to occur, and moreover, the table can be moved smoothly and accurately. .

[Brief explanation of drawings]

Fig. 1 is a plan view of one embodiment of the present invention, and Figs. 2, 3, and 4 are the - line and - line in Fig. 1, respectively.
FIG. 5 is a front view showing a part of the guide bar. 1...Base, 2...Guide bar, 2A...Groove, 3...
Lower bearing metal, 9... Drive mechanism, 11... Table, 12... Upper bearing metal, 13... Bearing member, 1
4...Recess.

Claims (1)

[Claims] 1. A feeding guide mechanism that slides and guides a table that is reciprocally movable with respect to a base using a guide bar,
The guide bar is rotatably supported in the circumferential direction via a bearing member, and a drive mechanism for rotating the guide bar is provided. a lower bearing element that is attached to the base and has an arcuate cross section that supports the lower part of the guide bar over substantially the entire travel stroke of the table; A feed guide mechanism comprising an upper bearing element having an arcuate cross section that slides on the upper part of a guide bar. 2. The feed guide mechanism according to claim 1, wherein a plurality of the guide bars are provided, and the drive mechanism rotates at least one of the guide bars in a direction different from that of the other guide bars. feeding guide mechanism. 3. The feed guide mechanism according to claim 1 or 2, wherein a recess is formed in the bearing member along the axial direction of the guide bar.