JP2000334604A - Air spindle unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cutting accuracy by preventing thermal expansion and flexure of the spindle of air spindle units mounted with a cutting blade at their spindle tip and arranged on a cutting attachment for the purpose of cutting workpieces. SOLUTION: An air spindle unit 10 comprises, at least, a spindle 11 equipped with a blade 21 for cutting a workpiece 27 at its front end, a spindle housing 23 including a radial bearing 24 and a thrust bearing 25 both for supporting the spindle 11 via air, and a stator 26 for rotating the spindle 11. The spindle 11 has an axial hollow 12 extending from an opening 13 made at the rear end until reaching just behind the front end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air spindle unit in which a cutting blade is mounted on the tip of a rotating shaft and is mounted on a cutting device and used for cutting a workpiece.

[0002]

2. Description of the Related Art As an air spindle unit mounted on a cutting device, an air spindle unit 20 having a configuration shown in FIG. 4 is known. In the air spindle unit 20, a rotating shaft 22 having a blade 21 mounted on the tip is rotatably supported in a non-contact state by a radial bearing 24 and a thrust bearing 25 provided in a spindle housing 23.

When the rotating shaft 22 is rotated at high speed by being driven by the stator 26, the blade 21 is rotated at high speed, and the whole air spindle unit 20 is lowered to hold the blade 21 rotating at high speed on the holding table 28. The workpiece 27 is cut by contacting the workpiece 27.

[0004]

However, there is a case where thermal expansion occurs due to rotation of the rotating shaft 22, which causes a deviation in the horizontal position of the blade 21, and a deviation in the cutting position. There is a problem that it is not performed precisely.

Further, the rotating shaft 22 is bent by its own weight, thereby causing a deviation in the vertical position of the blade 21 and an error in the cutting depth in some cases.

As described above, the air spindle unit has a problem in improving the cutting accuracy by preventing the thermal expansion and bending of the rotating shaft from occurring.

[0007]

As a specific means for solving the above-mentioned problems, the present invention provides a rotating shaft on which a blade for cutting a workpiece is mounted at a front end, An air spindle unit including at least a spindle housing including a radial bearing and a thrust bearing supported by air, and a stator that rotationally drives the rotating shaft, and includes:
Provided is an air spindle unit in which a hollow portion communicating from an opening that is opened at a rear end to a vicinity of a front end is formed.

[0008] A plurality of outer peripheral holes communicating with a cavity formed in the rotating shaft are formed on the outer periphery of the protruding portion protruding from the distal end of the spindle housing, and the plurality of outer peripheral holes are arranged at regular intervals. An additional requirement is that it is formed and that the cavity is supplied with a cooling medium.

In the air spindle unit configured as described above, since the heat dissipation is increased by forming the hollow portion on the rotating shaft, thermal expansion hardly occurs. Further, if a cooling medium is supplied to this hollow portion, In addition, thermal expansion can be effectively prevented, and horizontal displacement is less likely to occur. In addition, the weight is reduced by the provision of the hollow portion on the rotating shaft, so that the bending is reduced and the cutting depth accuracy in the workpiece is improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of an embodiment of the present invention, an air spindle unit 10 shown in FIG. 1 will be described. It is to be noted that the same parts as those of the conventional air spindle unit 20 shown in FIG.

Inside the rotary shaft 11, a hollow portion 12 (shown by a broken line in FIG. 1) having a constant diameter centered on the axis is formed in the axial direction. This cavity 12
The rear end, which is the side driven by the stator 26, is open at the opening 13. On the other hand, at the end on the front side, on which the blade 21 is mounted, on the outer periphery of the protruding portion 14 protruding from the tip of the spindle housing 23, the hollow portion 12 formed on the axis of the rotating shaft 11 is formed. A plurality of communicating outer peripheral holes 15 are formed.

Thus, the opening 13 is provided inside the rotating shaft 11.
Since the hollow portion 12 communicating with the outer peripheral hole 15 is formed, the rotating shaft 11 becomes lighter by that amount, so that bending is less likely to occur, the load due to centrifugal force is reduced, and higher speed rotation is possible. . In addition, since the bending is less likely to occur, the cutting depth accuracy of the blade 21 into the workpiece is improved, so that the cutting accuracy in the vertical direction is improved.

The hollow portion 12 does not necessarily have to be open on the front side, and may converge inside the rotary shaft 11 as long as it communicates with the vicinity of the front end. That is, if at least the opening 13 is opened, the heat dissipation is improved, so that thermal expansion can be prevented. Accordingly, since the displacement of the blade 21 in the horizontal direction due to thermal expansion can be prevented, the cutting accuracy in the horizontal direction is also improved.

As shown in FIG. 2, for example, four outer peripheral holes 15 communicating with the hollow portion 12 are all formed at equal intervals. The number and the interval of the outer peripheral holes 15 are not limited to the example of FIG. 2, but are preferably formed at equal intervals.

In the air spindle unit 10 configured as described above, if a cooling medium, for example, cool air is supplied from the opening 14 to the cavity 12, cooling of the rotating shaft 11 is promoted, and further effects are obtained. Thermal expansion of the rotating shaft 11 can be prevented.

The cavity 12 can be supplied with water as a cooling medium. In this case, the opening 13
Flows out from the outer peripheral hole 15 through the hollow portion 12. As shown in FIG. 3, the air used in the radial bearing 24 and the thrust bearing 25 is blown out from the gap 16 formed between the spindle housing 23 and the rotating shaft 11. Is supplied to the blade 21.

As described above, by using water as a cooling medium, the rotating shaft 11 can be more effectively cooled. Further, when water is supplied to the contact portion between the blade 21 and the workpiece 27, the water functions as a cooling medium for cooling the rotating shaft 11 and also functions as cutting water. In addition, cutting water can be saved.

[0018]

As described above, in the air spindle unit according to the present invention, since the hollow portion is formed in the rotating shaft, the heat dissipation is increased and the thermal expansion hardly occurs. By supplying the medium, thermal expansion can be effectively prevented, and horizontal displacement is less likely to occur, so that horizontal cutting accuracy is improved.

Further, the weight is reduced by the provision of the hollow portion on the rotating shaft, the bending is reduced, and the cutting depth accuracy in the workpiece is improved, so that the cutting accuracy in the vertical direction is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an air spindle unit according to the present invention.

FIG. 2 is an AA cut end view in FIG. 1;

FIG. 3 is an explanatory view showing a state in which water flows out from an outer peripheral hole and air is blown out from a gap.

FIG. 4 is a sectional view showing a conventional air spindle unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Air spindle unit 11 ... Rotating shaft 12 ... Hollow part 13 ... Opening part 14 ... Projection part 15 ... Outer peripheral hole 16 ... 20 ... Air spindle unit 21 ... Blade 22 ... Rotating shaft 23 ... Spindle housing 24 ... Radial bearing 25 ... Thrust Bearing 26 ... Stator 27 ... Workpiece 28 ... Holding table

Claims (4)

[Claims] 1. A spindle housing including a rotary shaft on which a blade for cutting a workpiece is mounted on a front end, a radial bearing and a thrust bearing for supporting the rotary shaft by air, and a rotary shaft. An air spindle unit comprising at least a stator driven to rotate, and a hollow portion communicating in the axial direction of the rotary shaft from an opening opened at a rear end portion to a vicinity of a front end portion. Air spindle unit on which is formed. 2. The air spindle unit according to claim 1, wherein a plurality of outer peripheral holes communicating with a cavity formed in the rotating shaft are formed in an outer periphery of the projecting portion projecting from a tip end of the spindle housing. 3. The air spindle unit according to claim 2, wherein the plurality of outer peripheral holes are formed at equal intervals. 4. The air spindle unit according to claim 1, wherein a cooling medium is supplied to the cavity.