JPH0516858Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cooling structure for a spindle motor in which a motor and an air bearing are integrally formed.

[Conventional technology]

A conventional example of this type of structure is shown in FIG. 2, in which a is a partially cutaway side view and b is a front view.

A spindle 10 in which a motor 1, a thrust bearing part 2, and a journal bearing part 3 are integrated,
Generally, it is fixed with a spindle support 5, and the shaft 4
Attach a cutter to the machine and cut the workpiece (workpiece).
Processing such as grinding, cutting, and grooving is performed.

The journal bearing part 3 includes an outer cover 3a that supports the journal bearing 3c, and an outer cylinder 3b for forming a cooling medium passage 3d in a recessed portion of the outer periphery of the outer cover 3a.
It is more established.

Here, the cooling medium passage 3d may be any cooling medium such as a liquid such as water or oil or a gas such as gas, and it may be formed in a spiral shape. A method of discharging the water to the outside may also be used.

[Problem that the invention attempts to solve]

With such a spindle 10, when the workpiece is machined in a large scale, the axial length L of the journal bearing part increases.
A certain length is required, and furthermore, the Y dimension (distance from the outer circumference of the journal bearing part to the axis of the shaft 4), which is the limit for the approach of the cutter to the workpiece, is limited to a certain value.

On the other hand, since the rigidity of the shaft 4 itself and the journal bearing 3c is determined by the diameter d of the inner peripheral surface of the journal bearing 3c, it is better to increase d in order to increase the rigidity.

Furthermore, in order to reduce thermal deformation of the journal bearing part 3 due to heat generated in the bearing parts 2 and 3, it is necessary to efficiently cool the journal bearing part 3 by providing a cooling medium passage 3d.

However, in the case of the spindle 10 having such a configuration, the wall thickness of the outer sheath 3a of the journal bearing part 3 is thin, so the rigidity is low and it is easily deflected.The natural frequency is low, and the spindle cannot be rotated at high speed. There were flaws.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cooling structure for an air bearing spindle motor that overcomes the drawbacks of the prior art and increases rigidity without increasing the Y dimension.

[Means for solving problems]

The present invention supports a cylindrical journal bearing that rotatably supports a rotating shaft in the axial direction, and has a concave groove spirally cut on the outer periphery to serve as a cooling medium passage. This is a cooling structure for an air bearing spindle motor, in which a cylindrical outer jacket is provided with a cylindrical outer cylinder surrounding the outer periphery, and the inner and outer central axes are eccentrically formed.

[Effect]

By making the outer diameter part of the outer sheath 3a eccentric by X with respect to the center of the shaft 4, the rigidity of the outer sheath 3a is improved without changing or enlarging the Y dimension. A concave portion is spirally cut in the outer diameter portion of 3a, and the outer cylinder 3b is covered to form a cooling medium passage 3d, thereby achieving smooth cooling.

〔Example〕

A configuration diagram of an embodiment of the present invention is shown in FIG.
A is a side sectional view, and b is a front view.

The same reference numerals indicate the same parts in all drawings.

By making the outer diameter part of the outer sheath 3a eccentric by an amount X with respect to the center of the shaft 4, the outer diameter of the outer sheath 3a can be increased without changing the Y dimension and thus not increasing the size.

Similarly, a concave groove is eccentrically cut in a spiral shape on the outer diameter portion, that is, the outer peripheral surface of the outer sheath 3a, and an outer cylinder 3b is formed on the outer peripheral surface of the outer sheath 3a so that the outer cylinder 3b covers the outer sheath 3a. By fitting and inserting the inner peripheral surfaces of the cooling medium passages 3d.

By doing so, the rigidity of the outer cover 3a is increased, the drawbacks of the conventional example are solved, and cooling is also performed appropriately.

Furthermore, since only the outer diameter and the concave portion of the outer sheath 3a are eccentrically processed, there is no need to increase the rigidity by using expensive special pipes such as square ones. The outer cylinder 3b is formed using a pipe, which does not increase the cost.

[Effect of idea]

Thus, according to the present invention, the axial dimension L of the journal bearing part is long and the dimension related to the approach of the cutter to the workpiece, that is, the rotating shaft center and the outer cylinder 3a.
The distance Y to the bottom of is small, the rigidity is high,
Furthermore, it is possible to realize a cooling structure for an air bearing spindle motor that has a sufficient cooling effect and is inexpensive to manufacture.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view and front view showing the configuration of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional example. 1...Motor, 2...Thrust bearing section, 3...
Journal bearing portion, 3a...outer cover, 3b...outer cylinder, 3c...journal bearing, 3d...cooling medium passage, 4...shaft.

Claims (1)

[Claims for Utility Model Registration] A rotating shaft is rotatably supported in the axial direction, and the outer periphery thereof is provided with a concave groove that serves as a cooling medium passage, and the outer periphery thereof is provided with a concave groove that serves as a cooling medium passage. In a cylindrical jacket with a cylindrical outer cylinder for enclosing, the central axis of the inner peripheral surface and the central axis of the outer peripheral surface are eccentric, so that the thick part of the jacket becomes the upper part and the thin part becomes the lower part. A cooling structure for an air bearing spindle motor, characterized in that it is formed as follows.