JPH076539B2 - Linear rolling guide device - Google Patents

Description

The present invention relates to a linear rolling guide device including a raceway and a bearing.

[Prior art]

For example, in a machine tool, the use of a rolling guide consisting of a raceway and a bearing instead of the slide guide as a device for guiding in the linear direction has the following advantages. That is, since the friction is small, it is possible to reduce the capacity of the drive motor, and since the phenomenon of the stuck slip does not occur, it is possible to easily perform accurate positioning.
In addition, it has high rigidity.

[Problems to be solved by the invention]

However, if a rolling guide device is adopted for a grinder, which is one of machine tools, for example, there are the following problems.
Hereinafter, description will be given with reference to the drawings.

FIG. 5 shows a side view of the grinder, and 1 is a grindstone. Reference numeral 2 is a main shaft that rotatably supports the grindstone 1.
It can slide in any direction. A bearing 4a constitutes the rolling guide device 4, and is fixed to the lower portion of the column 3.
Reference numeral 4b is a track that constitutes the rolling guide device 4, and is fixed to the bed 5. That is, the column 3 is slidable in the Z direction with respect to the bed 5. Reference numeral 6 denotes a table on which the work 7 is placed, which is slidable in the X direction.

When a vibration exciter is installed between the spindle 2 and the table 6 of the grinding machine adopting the rolling guide device 4 to apply a vibration force,
Each part of the grinder is displaced as shown by a chain double-dashed line in FIG. That is, the main shaft 2, the column 3 (hereinafter collectively referred to as the support portion 8) and the bed 5 have sufficient rigidity,
It can be seen that the displacement is caused by the rolling guide device 4. Furthermore, when the vibration frequency of the vibration exciter is changed, the horizontal axis represents the vibration frequency and the vertical axis represents the concurrence (however, the vertical axis represents logarithm). A curve (a) shown by a two-dot chain line in FIG. 4 is obtained.
That is, it can be seen that the supporting portion 8 is not a uniform curve, but has steep peaks and troughs and the difference between the peaks and troughs is large, so that the supporting portion 8 is largely displaced by the excitation force.

At the time of processing, due to grinding resistance between the grindstone 1 and the work 7,
The force mainly in the Y direction changes. In general, since the grindstone 1 and the work 7 are not completely uniform, the above-mentioned large force is not uniform, and the size varies and becomes an exciting force. Therefore, when the work 7 is processed by the grinder having the characteristic shown by the curve (a), the unevenness corresponding to the curve (a) is generated on the surface 9 of the work 7 due to the fluctuation of the grinding resistance.
Even if finishing is performed in order to eliminate the above-mentioned unevenness difference and improve the flatness of the surface 9, the grinding resistance applied to the grindstone 1 varies due to the unevenness formed on the surface 9, and the vibrating force is applied to the grindstone 1. Will join. For this reason, even if the finishing process is repeated, unevenness of several μm remains on the surface 9 and the flatness cannot be improved.

An object of the present invention is to solve the above-mentioned problems, and to provide a linear rolling guide device which does not impair the advantages of the rolling guide device 4 and which is less displaced by an exciting force.

[Means for solving problems]

The present inventor is based on that the cause of the displacement of the support portion 8 due to the above-mentioned vibration force is that there is no oil film formed between the ball in the bearing 4a and the track 4b, or at least there is little oil film. I found out that. Therefore, in order to achieve the above object, as shown in FIG. 1 which is an embodiment of the present invention, the permanent magnet 11 is mounted on the bearing 10a, and the fluid tank 12 is provided on the track 10b. The magnetic fluid 16 was filled in the gap 15 between the surface 13 and the inner surface 14 of the fluid tank 12 so as to face each other with a gap 15 of about 5 μm to 1 mm. In addition,
The permanent magnets 11 are alternately arranged with their north poles and south poles at a predetermined interval, and are placed in a multi-layered manner to form a magnetic circuit shown by a dotted line in the figure.

[Action]

In FIG. 1, a downward force indicated by an arrow is applied to the bearing 10a. If there is nothing in the gap 15, the balls inside the bearing 10a are elastically deformed, and the bearing 10a moves downward. However, since the magnetic fluid 16 is contained in the gap 15, the bearing 10a sinks while removing the magnetic fluid 16. Since the magnetic fluid 16 is viscous, the magnetic fluid 16 does not move immediately and viscous resistance acts upward on the bearing 10a. That is, the vibration damping device 17 composed of the bearing 10a, the fluid tank 12 and the magnetic fluid 16 described above constitutes a so-called dump pot. Since the bed 5 is little deformed and can be regarded as a rigid body, the equivalent vibration system of FIG. 2 is modeled as shown in FIG. In the figure, Ms is the support portion 8 related to the vibration mode in the Y direction.
Equivalent mass of. Similarly, Ks is the equivalent rigidity when the support 8 is regarded as a spring. Kb is the spring constant of the rolling bearing 4. Cd is a viscous resistance of the vibration damping device 13.

At the time of processing, the Y-direction excitation force applied to the grindstone 1 is transmitted to the support portion 8. However, with respect to the exciting force, the restoring force acting on the spring Kb depends on the displacement position of the vibration, the viscous resistance Cd depends on the displacement speed of the vibration, and the phase of the force is shifted by 90 degrees. Therefore, the vibration damping effect can be obtained. Here, since the fluid is magnetic fluid 16, it is a permanent magnet.
By changing the magnitude of the magnetic field by 11, the viscous resistance Cd
Can be arbitrarily adjusted between an intrinsic viscous resistance in the absence of a magnetic field and an apparent viscous resistance in the presence of a larger magnetic field. Therefore, when the same vibrating force as when the curve (a) of FIG. 4 is obtained is applied to the spindle 2 and a viscous resistance Cd that reduces the vibration of the grindstone 1 in FIG. The response curve of is the curve shown in FIG. That is, the curve (b) is a curve having less unevenness than the curve (a), and the surface 9 after processing has excellent flatness.

〔Example〕

FIG. 1 is an embodiment of the present invention, and FIG. 2 is a side view of a grinding machine to which the linear rolling guide device of the present invention is applied. The same parts as those in FIG. 5 are designated by the same reference numerals.

10a is a bearing. 10b is the orbit. Reference numeral 11 denotes a permanent magnet mounted on the bearing 10a, and the N poles and the S poles of the permanent magnets are alternately arranged at predetermined intervals so as to form a magnetic circuit shown by a dotted line. 12 is a fluid tank provided on the track 10b. A magnetic fluid 16 is filled in the gap 15 between the surface 13 of the bearing 10a and the inner surface 14 of the fluid tank 12. Reference numeral 18 denotes a plurality of small-diameter holes provided in the bearing 10a, which communicates the surface 13 with the side surface 19 on the outside air side. Further, the magnetic field generated by the permanent magnet 11 is set to a value that reduces the apparent viscous resistance Cd of the magnetic fluid 16 even when the whetstone 1 vibrates.

The operation will be described below.

At the time of processing, a force of varying size, that is, a vibrating force is mainly applied to the whetstone 1 in the Y direction. Although the exciting force is transmitted to the support portion 8, the vibration damping device 17 reduces the displacement of the support portion 8.

Further, in this embodiment, the hole 18 allows the support 8 to move smoothly in the Z direction. That is, when the support portion 8 is moved in the Z direction with the gap 15 being narrow and the surface 13 being inclined with respect to the inner surface 14, an upward force is generated on the support portion 8 due to the so-called fluid wedge action. , I can't move smoothly. However, in this embodiment,
Since the pressure generated in the magnetic fluid 16 can be released by the hole 18, the wedge action of the fluid is hardly generated, and the support portion 8 can be smoothly moved in the Z direction.

Furthermore, since the permanent magnet 11 is also arranged on the side surface 19 of the bearing 10a, it has a damping effect not only on the exciting force in the Y direction but also in the X direction.

In the present embodiment, the permanent magnets 11 are arranged in the direction perpendicular to the magnetic fluid 16, but it goes without saying that they may be arranged in parallel. Also, bearing 10a and track 1
0b is not limited to a ferromagnetic material, and may be a non-magnetic material.

〔The invention's effect〕

As described in detail above, since the linear rolling guide device of the present invention can damp the applied exciting force, it can be a device having a small displacement with respect to the exciting force and improves the machining accuracy. be able to. In addition, surface 13 and inner surface 14
Since it is not in contact with, there is almost no frictional resistance, and the advantages of the rolling guide are not impaired.

[Brief description of drawings]

1 and 2 are diagrams showing an embodiment of the present invention. 3 to 4 are explanatory views of the present invention. FIG. 5 is an explanatory diagram of a conventional technique. 4 ... Rolling guide device, 4a, 10a ... Bearing, 4b, 1
0b ... Orbit, 11 ... Permanent magnet, 12 ... Fluid tank, 13 ... Surface, 14 ... Inner surface, 15 ... Gap, 16 ... Magnetic fluid, 17 ...
Vibration damping device.

Claims (1)

[Claims] 1. A linear rolling guide device comprising a raceway and a bearing, wherein a magnet is placed on the surface of the bearing and a hole for connecting the surface of the bearing to the atmosphere is provided.
A linear rolling guide device characterized in that a fluid tank for containing a magnetic fluid is provided on the raceway, and a gap between the surface of the bearing and the inner surface of the fluid tank facing the bearing is 5 μm to 1 mm.