JP7347175B2 - Spindle device - Google Patents

Description

The present invention relates to a spindle device for a machine tool.

A main spindle of a main spindle device of a machine tool (such as a machining center) is provided with a tool attachment/detachment hole at the front end in the axial direction, into which a tool holder is removably attached. When the tool holder is removed, foreign matter such as chips may be trapped in the inner peripheral surface of the tool attachment/detachment hole. Therefore, in the spindle device disclosed in Patent Document 1, a cleaning process is performed in which air is supplied to the tool attachment/detachment hole (tapered hole) to discharge foreign matter.

That is, as shown in FIG. 11, this main shaft 110 is provided with an air discharge hole 113 on the tapered surface 112 of the tool attachment/detachment hole 111, and an air discharge hole 113 is provided on the front side of a drawbar (push rod) 120 coaxially arranged within the main shaft 110. An injection port 115 is provided on the side near the end face. The air discharge hole 113 discharges air a1 diagonally toward the front side of the tool attachment/detachment hole 111. The injection port 115 injects air a2 in the radial direction of the space 114 provided on the drawbar 120 side with respect to the tool attachment/detachment hole 111.

JP 2019-34354 Publication

When the air flow in the conventional spindle device was obtained by simulation processing, it was found that the air a1 discharged from the air discharge hole 113 flows along the tapered surface 112 of the tool attachment/detachment hole 111 toward the front opening of the tool attachment/detachment hole 111. Flows in a spiral. Further, the air a2 injected from the injection port 115 expands in the radial direction in the space 114, and then flows gently toward the front opening of the tool attachment/detachment hole 111. Then, it merges with the air a1 discharged from the air discharge hole 113, and flows spirally along the tapered surface 112 of the tool attachment/detachment hole 111 toward the front opening of the tool attachment/detachment hole 111.

In this way, the air a1 discharged from the air discharge hole 113 and the air a2 jetted from the injection port 115 spiral along the tapered surface 112 of the tool attachment/detachment hole 111 toward the front opening of the tool attachment/detachment hole 111. flows to Therefore, it has been found that a low pressure region LP (the region surrounded by the dashed line in the figure) occurs around the axis CL of the tool attachment/detachment hole 111. Therefore, a portion of the air a1 and a2 released from the front opening of the tool attachment/detachment hole 111 is sucked into the low pressure region LP of the tool attachment/detachment hole 111. If the sucked air contains foreign matter, the foreign matter will be taken into the tool attachment/detachment hole 111 again.

In addition, a high-speed air discharge flow (strong air discharge flow) is generated at a position near the air discharge hole 113, but it decelerates and becomes a low-speed air discharge flow (weak air discharge flow) at a position away from the air discharge hole 113. It turns out that you can only get it. For this reason, there is a risk that the foreign matter discharging ability in the tool attachment/detachment hole 111 will be uneven, and the foreign matter may remain.

SUMMARY OF THE INVENTION An object of the present invention is to provide a spindle device capable of a cleaning process that can reliably remove foreign matter taken into a tool attachment/detachment hole by supplying air.

The spindle device according to the present invention includes a fixed part, and a tool holder is arranged in the fixed part so as to be relatively rotatable about an axis with respect to the fixed part, and a tool holder is attached to and detached from a tool attachment hole provided at one end in the axial direction. a cylindrical rotating body that can be attached to the rotating body; and a cylindrical rotating body that is arranged within the rotating body so as to be able to rotate integrally with the rotating body and to be movable relative to the rotating body in the axial direction, and at one end in the axial direction. a shaft-shaped drawbar for clamping or unclamping the tool holder, the rotating body is provided with a swirling flow discharge hole for discharging air swirling around the axis in the tool attachment/detachment hole, and the drawbar is provided with a straight flow discharge hole that discharges air that travels straight in the axial direction in the tool attachment/detachment hole.

In the spindle device having the above configuration, the air discharged from the straight flow discharge hole travels straight in the axial direction in the tool attachment/detachment hole. Air discharged from each swirling flow discharge hole swirls along the inner circumferential surface of the tool attachment/detachment hole. The straight flow discharged from the straight flow discharge hole is twisted by the swirling flow discharged from each swirl flow discharge hole, and rotates periodically along the inner circumferential surface of the tool attachment hole with the straight flow discharge hole as the center of rotation. rotate.

As a result, almost no low pressure region is generated around the axis of the tool attachment/detachment hole, and it is possible to suppress air released from the tool attachment/detachment hole from being sucked into the tool attachment/detachment hole again. Therefore, it is possible to reduce the possibility that foreign matter will be taken into the tool attachment/detachment hole again. Furthermore, since an air discharge flow that rotates along the inner circumferential surface of the tool attachment/detachment hole is obtained, it is possible to prevent unevenness in the foreign matter discharging ability. Since the entire inner peripheral surface of the tool attachment/detachment hole can be cleaned, it is possible to reduce the amount of foreign matter remaining in the tool attachment/detachment hole.

FIG. 2 is a cross-sectional view showing the main parts of the spindle device of the machine tool. FIG. 3 is a sectional view showing the main part of the main shaft of the main shaft device. FIG. 2B is a sectional view taken along line IIB-IIB in FIG. 2A. It is a perspective view showing only the outlines of the tool attachment/removal hole of the spindle, the straight flow discharge hole, and the swirling flow discharge hole (the outline of the back side is omitted for convenience), and shows the state of air discharge from the straight flow discharge hole. It is a perspective view showing only the outlines of the tool attachment/removal hole, the straight flow discharge hole, and the swirling flow discharge hole of the spindle (the outline of the back side is omitted for convenience), and shows the initial state of air discharge from the straight flow discharge hole and the swirling flow discharge hole. show. This is a perspective view showing only the outlines of the tool attachment/removal hole, the straight flow discharge hole, and the swirling flow discharge hole of the spindle (the outline of the back side is omitted for convenience), and shows changes in the state of air discharge from the straight flow discharge hole and the swirl flow discharge hole. shows. This is a perspective view showing only the contours of the tool attachment/removal hole, the straight flow discharge hole, and the swirling flow discharge hole of the spindle (the outline of the back side is omitted for convenience), and it simulates the state of air discharge from the straight flow discharge hole and the swirl flow discharge hole. Shows the processing results. In Fig. 4, a diagram showing the simulation processing results of the change over time in the velocity distribution of air from the straight flow discharge hole in a radial cross section when the front opening of the tool attachment/detachment hole of the main spindle is viewed in the axial direction from the front side to the rear side. It is. This is a perspective view showing only the contours of the tool attachment/removal hole, the straight flow discharge hole, and the swirling flow discharge hole of the spindle (the outline of the back side is omitted for convenience). The simulation processing results of the state of air discharge from the swirling flow discharge hole are shown. In Figure 6, the simulation processing results of the first half of the velocity distribution of air from the straight flow discharge hole in the radial cross section when the front opening of the tool attachment/detachment hole of the spindle is viewed in the axial direction from the front side to the rear side are shown. FIG. In Figure 6, the simulation processing results of the second half of the speed distribution of air from the straight flow discharge hole in the radial cross section when the front opening of the tool attachment/detachment hole of the main spindle is viewed in the axial direction from the front side to the rear side are shown. FIG. It is a sectional view showing the principal part of the spindle of the spindle device of another example. FIG. 8B is a sectional view taken along line VIIIB in FIG. 8A. In the spindle device of Fig. 8A, simulation of the change over time in the first half of the velocity distribution of air from the straight flow discharge hole in the radial cross section when the front opening of the tool attachment/detachment hole of the spindle is viewed in the axial direction from the front side to the rear side. It is a figure which shows a processing result. In the spindle device of FIG. 8A, simulation of the second half of the change over time in the velocity distribution of air from the straight flow discharge hole in the radial cross section when the front opening of the tool attachment/detachment hole of the spindle is viewed in the axial direction from the front side to the rear side. It is a figure which shows a processing result. 3 is a flowchart illustrating a cleaning process operation by air discharge in the tool attachment/detachment hole of the spindle device. FIG. 2 is a cross-sectional view showing the main part of the main shaft of a conventional main shaft device, and shows the state of air discharge.

(1. Configuration of spindle device 1)
A spindle device of a machine tool (such as a machining center) according to this embodiment of the present invention will be described with reference to FIG. The main spindle device 1 of this embodiment mainly includes a housing 10 (corresponding to a fixed part), a main shaft 20 (corresponding to a rotating body), bearings 30, 40, a main spindle motor 50, a drawbar 60, a clamp unit 70, a switching device 80, and a control device. It is equipped with a device 90 and the like.

The main shaft 20 and the like of the main shaft device 1 rotate around a central axis line (hereinafter referred to as axis line) CL. In the following description, the left side in the axis CL direction may be referred to as the front side, and the right side in the axis CL direction may be referred to as the rear side.

The housing 10 includes a front housing 11, a rear housing 12, and a housing cap 13. Each housing 11, 12 and housing cap 13 are formed into a substantially cylindrical shape. The housings 11 and 12 and the housing cap 13 are connected and fixed together by a predetermined means, so that the housing 10 is formed into a substantially cylindrical shape. At this time, the predetermined means for connecting and fixing includes, for example, fastening using bolts or the like.

The front housing 11 includes a first cylindrical portion 11a (left side in FIG. 1) and a second cylindrical portion 11b (right side in FIG. 1) that are coaxially formed. The outer diameter and inner diameter of the first cylindrical portion 11a are smaller than the outer diameter and inner diameter of the second cylindrical portion 11b, respectively.

The inner circumferential surface of the first cylindrical portion 11a includes a large diameter inner circumferential surface 11a1 (left side in FIG. 1) that supports the outer circumferential surface of the outer ring of the bearing 30, and a small diameter inner circumferential surface 11a2 (right side in FIG. 1). . The large-diameter inner circumferential surface 11a1 and the small-diameter inner circumferential surface 11a2 are connected by a connecting surface 11a3 formed on a plane perpendicular to the axis CL. The connecting surface 11a3 contacts the right end surface of the outer ring of the bearing 30, which will be described later, and supports the right end surface.

An outer circumferential surface of a stator 52 that constitutes a main shaft motor 50, which will be described later, is fixed to an inner circumferential surface 11b1 of the second cylindrical portion 11b. The small-diameter inner circumferential surface 11a2 of the first cylindrical portion 11a and the inner circumferential surface 11b1 of the second cylindrical portion 11b are connected by a connecting surface 11b2 formed on a plane orthogonal to the axis CL.

The rear housing 12 is formed in a cylindrical shape, and the inner peripheral surface of the rear housing 12 includes a large diameter inner peripheral surface 12a (left side in FIG. 1) that supports the outer peripheral surface of the outer ring of the bearing 40, and a small diameter inner peripheral surface. 12b (on the right side in FIG. 1). The large-diameter inner circumferential surface 12a and the small-diameter inner circumferential surface 12b are connected by a connecting surface 12c formed on a plane orthogonal to the axis CL.

The front end surface of the rear housing 12 includes an outer end surface 12d located on the radially outer side with respect to the axis CL, and an inner peripheral end surface 12e located on the radially inner side. The outer circumferential end surface 12d is formed so as to be retreated rearward from the inner circumferential end surface 12e. The outer peripheral end surface 12d and the inner peripheral end surface 12e are connected by a connecting peripheral surface 12f centered on the axis CL. The inner circumferential surface 11b1 of the second cylindrical portion 11b of the front housing 11 engages with this connecting circumferential surface 12f.

The housing cap 13 is attached to the front end (left end in FIG. 1) of the front housing 11. That is, the housing cap 13 includes a protrusion 13a extending toward the rear side. The large-diameter inner circumferential surface 11a1 of the first cylindrical portion 11a of the front housing 11 engages with the outer circumferential surface of the protrusion 13a.

The main shaft 20 is arranged within the housing 10. The main shaft 20 is formed in a substantially cylindrical shape and is arranged so as to be rotatable relative to the housing 10 around the axis CL. The main shaft 20 includes a through hole 21 coaxial with the axis CL.

The tool holder 8, the clamp unit 70, and the drawbar 60 are arranged in the through hole 21 in this order from the left in FIG. 1. Note that FIG. 1 shows a clamped state in which the collet 71 constituting the clamp unit 70 is closed in the radial direction of the main shaft 20 and clamps (holds) the pull stud 8a of the tool holder 8.

The through hole 21 includes, in order from the left in FIG. 1, a tool attachment/detachment hole 21a and a drawbar accommodation hole 21b. The tool attachment/detachment hole 21a includes a tapered hole 21a1 whose front opening has a large diameter, and a cylindrical column hole 21a2 that communicates with the tapered hole 21a1 and has the same diameter as the rear opening of the tapered hole 21a1. , a cylindrical unclamping hole 21a3 having a diameter larger than that of the column hole 21a2.

The tapered hole 21a1 of the tool attachment/detachment hole 21a removably holds the taper shank 8b of the tool holder 8. The column hole 21a2 of the tool attachment/detachment hole 21a is provided to facilitate attachment/detachment of the taper shank 8b to/from the taper hole 21a1. The unclamping hole 21a3 of the tool attachment/detachment hole 21a accommodates the collet 71 opened in the radial direction of the main shaft 20, that is, the collet 71 in an unclamped state.

The drawbar accommodation hole 21b communicates with the unclamping hole 21a3 of the tool attachment/detachment hole 21a, is formed in a cylindrical shape with a smaller diameter than the diameter of the unclamping hole 21a3 of the tool attachment/detachment hole 21a, and accommodates the clamp unit 70 and the drawbar 60 in a clamped state. do.

The main shaft 20 includes a first cylindrical portion 20a, a second cylindrical portion 20b, and a third cylindrical portion 20c in order from the left in FIG. The first cylindrical portion 20a to the third cylindrical portion 20c are arranged in descending order of outer diameter. However, the present invention is not limited to this embodiment, and the second cylindrical portion 20b may be the largest in the above arrangement.

The outer peripheral surface of the first cylindrical portion 20a engages with the inner peripheral surface of the housing cap 13. A bearing 30 is attached to the outer circumferential side of the front end of the second cylindrical portion 20b, and the outer circumferential surface of the second cylindrical portion 20b supports the inner circumferential surface of the inner ring of the bearing 30. Thereby, the front end of the main shaft 20 is rotatably supported by the housing 10 (the large-diameter inner circumferential surface 11a1 of the first cylindrical portion 11a of the front housing 11) via the bearing 30.

The bearing 30 is a known parallel combination type angular contact ball bearing. However, the parallel combination type angular contact ball bearing is illustrated as an example to the last, and the bearing 30 may be of another type depending on the usage conditions.

A connecting surface 20d formed by a step between the first cylindrical portion 20a and the second cylindrical portion 20b of the main shaft 20 comes into contact with the left end surface of the inner ring of the bearing 30. Further, the rear end surface 13a1 of the protrusion 13a of the housing cap 13 contacts the left end surface of the outer ring of the bearing 30, and the connecting surface 11a3 of the first cylindrical portion 11a of the front housing 11 contacts the right end surface of the outer ring of the bearing 30. They abut and sandwich the outer ring of the bearing 30 from both left and right sides.

Furthermore, the inner circumferential surface of a rotor 51 constituting the main shaft motor 50 is fixed onto the outer circumferential surface of the second cylindrical portion 20b at the central portion in the axial direction. Note that for convenience in assembling the bearing 30 and rotor 51 to the main shaft 20, the outer diameter of the portion of the second cylindrical portion 20b to which the rotor 51 is fixed is slightly smaller than the outer diameter of the portion where the bearing 30 is supported. is preferable. However, the present invention is not limited to this aspect, and the outer diameter of the portion where the bearing 30 is supported may be the same as the outer diameter of the portion where the rotor 51 is fixed.

The main shaft motor 50 includes a rotor 51 and a stator 52. The stator 52 is arranged on the outer peripheral surface side of the rotor 51. Specifically, the stator 52 is fixed to the inner circumferential surface 11b1 of the second cylindrical portion 11b of the front housing 11 so that the inner circumferential surface has a predetermined gap with the outer circumferential surface of the rotor 51. The main shaft 20 is driven to rotate integrally with the rotor 51 by a main shaft motor 50 controlled by a control device 90 .

A bearing 40 is attached to the outer circumferential surface side of the third cylindrical portion 20c, and the outer circumferential surface of the third cylindrical portion 20c supports the inner circumferential surface of the inner ring of the bearing 40. Thereby, the rear end portion of the main shaft 20 is rotatably supported by the housing 10 (the large-diameter inner circumferential surface 12a of the rear housing 12) via the bearing 40.

The bearing 40 is composed of a single known cylindrical roller bearing. In this way, the main shaft 20 is supported by the bearings 30, 40 at both ends with the rotor 51 in between, so that it can rotate stably. However, the cylindrical roller bearing is merely an example, and the bearing 40 may be of another type depending on the usage conditions.

The drawbar 60 is a shaft-shaped member, and is inserted into the drawbar accommodation hole 21b of the through hole 21 of the main shaft 20, as described above. It can rotate integrally with the main shaft 20 by driving the main shaft motor 50 controlled by the control device 90, and can move relative to the main shaft 20 in the direction of the axis CL by driving an unillustrated drive device controlled by the control device 90. will be placed in

A claw-shaped collet 71 forming a clamp unit 70 is engaged with the drawbar 60 at its front end (left end in FIG. 1). The collet 71 of the clamp unit 70 is in a clamped state in which it grips the pull stud 8a of the tool holder 8 and clamps the tool holder 8 as the drawbar 60 moves back and forth in the direction of the axis CL; This device is capable of switching between an unclamping state in which the tool holder 8 is opened and the tool holder 8 is unclamped.

For example, four collets 71 are provided on the outer periphery of the front end of the drawbar 60 at intervals of 90 degrees. Note that the collet 71 is not limited to a four-claw shape, but may have any configuration as long as it can open and close to grip and release the pull stud 8a provided in the tool holder 8. Note that since the clamp unit 70 is a well-known technique, a detailed description of the configuration will be omitted.

Here, as described in the problem to be solved, in the conventional spindle device, the air a1 discharged from the air discharge hole 113 and the air a2 jetted from the injection port 115 are directed toward the front opening of the tool attachment/detachment hole 111. It flows spirally along the tapered surface 112 of the tool attachment/detachment hole 111. Therefore, a portion of the air released from the front opening of the tool attachment/detachment hole 111 is sucked into the low pressure region LP generated around the axis CL of the tool attachment/detachment hole 111. If the sucked air contains foreign matter, the foreign matter will be taken into the tool attachment/detachment hole again.

In addition, since only a low-speed air discharge flow (weak air discharge flow) can be obtained at a position away from the air discharge hole 113, the ability to discharge foreign matter in the tool attachment/detachment hole 111 is uneven, and foreign matter remains. There is a risk. In view of the above, the inventor of the present application has created a system in which a single high-speed air discharge flow (strong air discharge flow) directed from the rear side of the tool attachment/detachment hole 21a is rotated along the inner circumferential surface of the tool attachment/detachment hole 21a. We have discovered that the above problems can be solved by doing so.

The spindle device 1 of this embodiment is provided with a swirling flow discharge hole 22 and a rectilinear flow discharge hole 61 in order to generate the above-mentioned air discharge flow. That is, as shown in FIGS. 1, 2A, and 2B, the column hole 21a2 of the tool attachment/detachment hole 21a has a swirling flow discharge that discharges air in the tangential direction of one circumference on the inner peripheral surface of the column hole 21a2. A hole 22 is provided. The openings of the swirling flow discharge holes 22 are provided at four locations (90 degree intervals) at equal angular intervals, in this example, on one circumference of the inner peripheral surface of the column hole 21a2.

As shown in FIG. 1, each swirling flow discharge hole 22 is communicated with an air supply passage 23 extending from the front side to the rear side inside the main shaft 20, and is connected to an air supply source 81 via an air pipe 24 and an on-off valve 25. connected to. The opening/closing operation of the on-off valve 25 is controlled by a control device 90. As a result, the air discharged from each swirling flow discharge hole 22 flows along one circumference on the inner peripheral surface of the column hole 21a2, and therefore swirls within the column hole 21a2 and the unclamping hole 21a3.

Furthermore, as shown in FIGS. 1, 2A, and 2B, the drawbar 60 has a rectilinear flow discharge hole 61 that discharges air from the rear side toward the front side in the axis CL direction in the tool attachment/detachment hole 21a, which is coaxial with the axis CL. Established in The opening of the swirling flow discharge hole 22 is such that when the drawbar 60 moves forward and the collet 71 opens in the unclamping hole 21a3, the opening of the straight flow discharge hole 61 is in the direction of air discharge from the straight flow discharge hole 61. It is provided at a position on the front side of the opening.

As shown in FIG. 1, the straight flow discharge hole 61 is connected to a switching device 80 that can switch between supplying air and coolant through a pipe 62 on the rear side of the drawbar 60. This switching device 80 is connected to an air supply source 81 and a coolant liquid supply source 82, respectively. The switching operation of the switching device 80 is controlled by a control device 90. Thereby, the air discharged from the straight flow discharge hole 61 travels straight from the rear side to the front side in the direction of the axis CL in the tool attachment/detachment hole 21a.

In such a configuration, as shown in FIG. 3A, the air At discharged from the rectilinear flow discharge hole 61 flows linearly along the axis CL in the order of the unclamp hole 21a3, the column hole 21a2, and the tapered hole 21a1. As shown in FIG. 3B, the air As discharged from each swirling flow discharge hole 22 flows in a swirling manner along the inner peripheral surface of the column hole 21a2.

Here, as described above, the opening of the swirling flow discharge hole 22 is provided at a position on the front side of the opening of the straight flow discharge hole 61 in the air discharge direction discharged from the straight flow discharge hole 61. . Therefore, as shown in FIG. 3C, the linear air At discharged from the straight flow discharge hole 61 is twisted by the swirling air As discharged from each swirl flow discharge hole 22, and 61 as the center of rotation, it periodically rotates in the R direction along the inner circumferential surface of the tool attachment/detachment hole 21a.

As described above, a low pressure region is hardly generated around the axis CL of the tool attachment/detachment hole 21a, and it is possible to suppress the air released from the front opening of the tool attachment/detachment hole 21a from being sucked into the tool attachment/detachment hole 21a again. Therefore, it is possible to reduce the possibility that foreign matter will be taken into the tool attachment/detachment hole 21a again. Further, since a high-speed air discharge flow (strong air discharge flow) rotating along the inner circumferential surface of the tool attachment/detachment hole 21a is obtained, it is possible to prevent unevenness in the foreign matter discharge ability. Since the entire inner circumferential surface of the tool attachment/detachment hole 21a can be cleaned, foreign matter remaining in the tool attachment/detachment hole 21a can be reduced.

(2. Air flow in spindle device 1)
Next, the air flow in the tool attachment/detachment hole 21a of the spindle device 1 described above was simulated, and the simulation results shown in FIGS. 4 and 5 were obtained. Here, as described above, the air As discharged from the swirling flow discharge hole 22 is used only to rotate the air At discharged from the straight flow discharge hole 61. The air At is used to remove foreign matter in the tool attachment/detachment hole 21a.

Therefore, the air flow conditions at this time were set so that the flow rate of the air At discharged from the straight flow discharge hole 61 was greater than the flow rate of the air As discharged from the swirl flow discharge hole 22. FIG. 4 shows the air flow of air As and At when looking through the tool attachment/detachment hole 21a. FIG. 5 shows the velocity distribution of the air At in a radial cross section when the front opening of the tool attachment/detachment hole 21a is viewed from the front side to the rear side in the direction of the axis CL. In Figure 5, the velocity distribution of the air At makes one rotation in the order of (a), (b), (c), (d), (e), (f), and (a) over time at equal time intervals. Show change.

As shown in FIG. 4, the air As discharged from the swirling flow discharge hole 22 swirls and flows in the direction of the arrow shown by the dashed line in the column hole 21a2 and the unclamp hole 21a3 of the tool attachment/detachment hole 21a. The air At discharged from the straight flow discharge hole 61 is twisted by a swirling flow in the column hole 21a2 and the unclamp hole 21a3 of the tool attachment/detachment hole 21a, and is twisted along the inner circumferential surface of the tapered hole 21a1. It flows in a undulating manner in the direction of the arrow shown by the two-dot chain line. As shown in FIGS. 5(a) to 5(f), the air At discharged from the straight flow discharge hole 61 rotates at a cycle of 0.05 seconds along the inner peripheral surface of the tapered hole 21a1. .

In this way, the air At discharged from the straight flow discharge hole 61 flows as a high-speed air discharge flow (strong air discharge flow) that rotates along the inner peripheral surface of the tool attachment/detachment hole 21a. The entire inner peripheral surface of 21a can be cleaned. Therefore, it is possible to reduce the amount of foreign matter remaining in the tool attachment/detachment hole 21a. In addition, in FIGS. 5(c), (d), and (e), although the suction area LP is generated, it is temporary and at a low speed, so that the intake of foreign matter can be suppressed.

(3. Effect of the number of swirl flow discharge holes 22)
Next, the influence of the number of swirling flow discharge holes 22 was examined. Specifically, the air flow in the tool attachment/detachment hole 21a when the number of swirling flow discharge holes 22 is reduced from four to one is simulated, and the results are shown in FIGS. 6, 7A, and 7B. The simulation processing results shown in are obtained.

The air flow conditions at this time are such that the flow rate of the air As discharged from the swirl flow discharge holes 22 is set to one fourth compared to the air flow conditions when four swirl flow discharge holes 22 are provided. , the flow rate of the air At discharged from the straight flow discharge hole 61 was set to be the same. FIG. 6 shows the air flow of air As and At when looking through the tool attachment/detachment hole 21a. 7A and 7B show the velocity distribution of the air At in a radial cross section when the front opening of the tool attachment/detachment hole 21a is viewed from the front side to the rear side in the direction of the axis CL. In FIGS. 7A and 7B, the air At is It shows changes over time at equal time intervals in the velocity distribution during one revolution.

As shown in FIG. 6, the air As discharged from the swirling flow discharge hole 22 swirls and flows in the direction of the arrow shown by the dashed line in the column hole 21a2 and the unclamp hole 21a3 of the tool attachment/detachment hole 21a. However, since the number of swirling flow discharge holes 22 is reduced from four to one, the swirling flow is weaker than the swirling flow shown in FIG. 4 .

The air At discharged from the straight flow discharge hole 61 is twisted by a swirling flow in the column hole 21a2 and the unclamp hole 21a3 of the tool attachment/detachment hole 21a, and is twisted along the inner circumferential surface of the tapered hole 21a1. It flows in a undulating manner in the direction of the arrow shown by the two-dot chain line. However, since the swirling flow in the column hole 21a2 and the unclamping hole 21a3 of the tool attachment/detachment hole 21a is weaker than the swirling flow shown in FIG. 4, the waviness is smaller than the undulation shown in FIG.

As shown in FIGS. 7A(a)-(d) and FIGS. 7B(a)-(c), the air At discharged from the straight flow discharge hole 61 is zero along the inner circumferential surface of the tapered hole 21a1. It rotates with a period of .32 seconds. Since the strength of the swirling flow is reduced by reducing the number of swirling flow discharge holes 22 from four to one, the period (0.05 seconds).

In this way, the air At discharged from the straight flow discharge hole 61 flows as a high-speed air discharge flow (strong air discharge flow) that rotates along the inner peripheral surface of the tool attachment/detachment hole 21a. The entire inner peripheral surface of 21a can be cleaned. Therefore, even if the number of swirling flow discharge holes 22 is reduced from four to one, it is possible to reduce the amount of foreign matter remaining in the tool attachment/detachment hole 21a. However, in terms of the number of swirling flow discharge holes 22, it is desirable to provide at least two locations (180 degrees apart) in order to balance the weight of the rotating body.

(4. Effect of arrangement position of swirl flow discharge hole 22)
Next, the influence of the arrangement position of the swirling flow discharge hole 22 was studied. Specifically, as shown in FIGS. 8A and 8B, the location of the swirling flow discharge hole 22 was moved from the column hole 21a2 of the tool attachment/detachment hole 21a to the tapered hole 21a1. The tapered hole 21a1 is provided with a swirling flow discharge hole 22 that discharges air in a tangential direction of one circumference on the inner peripheral surface of the tapered hole 21a1.

The openings of the swirling flow discharge holes 22 are provided at four locations (90 degree intervals) at equal angular intervals, in this example, on one circumference of the inner peripheral surface of the tapered hole 21a1. In such a configuration, the air flow in the tool attachment/detachment hole 21a was simulated to obtain the simulation results shown in FIGS. 9A and 9B.

The air flow conditions at this time are the same as the air flow conditions when the swirling flow discharge hole 22 is provided in the column hole 21a2, that is, the flow rate of the air discharged from the swirling flow discharge hole 22 is set to be the same, and the straight flow The flow rate of air discharged from the discharge hole 61 was set to be the same. In FIGS. 9A and 9B, FIGS. 9A (a), (b), (c), (d), (e), and FIG. , FIG. 9A(a) shows changes over time at equal time intervals in the velocity distribution when the air At makes one revolution.

As shown in FIGS. 9A-(e) and 9B(a)-(e), the air At discharged from the straight flow discharge hole 61 is 0.09 mm along the inner circumferential surface of the tapered hole 21a1. It rotates at a period of seconds, which is slightly slower than the period (0.05 seconds) shown in FIGS. 5(a) to 5(f). However, no suction area was observed, and the intake of foreign matter could be suppressed.

In addition, the air At discharged from the straight flow discharge hole 61 flows as a high-speed air discharge flow (strong air discharge flow) that rotates along the inner peripheral surface of the tool attachment/detachment hole 21a. The entire inner peripheral surface can be cleaned. Therefore, even if the swirling flow discharge hole 22 is located away from the straight flow discharge hole 61, it is possible to reduce the amount of foreign matter remaining in the tool attachment/detachment hole 21a.

(5. Cleaning operation of tool attachment/detachment hole 21a)
Next, a cleaning process operation by air discharge in the tool attachment/detachment hole 21a of the spindle device 1 will be described with reference to the flowchart of FIG. 10. Note that this cleaning processing operation is completed by discharging air for a predetermined time after the machining process of the workpiece in the machine tool is completed.

The control device 90 of the spindle device 1 determines whether or not the machining process in the machine tool is finished (step S1), and when the machining process in the machine tool is finished, stops the operation of the coolant liquid supply source 82 (step S2). ).

Then, the control device 90 of the spindle device 1 moves the drawbar 60 to the front side and shifts the clamp unit 70 from the clamped state to the unclamped state (step S3). The control device of the machine tool operates the automatic tool changer to remove the tool holder from the spindle device 1.

The control device 90 of the spindle device 1 starts the operation of the air supply source 81 (step S4), opens the on-off valve 25, and discharges air from each swirling flow discharge hole 22 (step S5). Then, the control device 90 of the spindle device 1 operates the switching device 80 to switch the supply of coolant liquid to the supply of air, and discharges air from the straight flow discharge hole 61 (step S6).

The control device 90 of the spindle device 1 determines whether or not the operating time of the air supply source 81 has elapsed for a predetermined time (step S7), and when the operating time of the air supply source 81 has elapsed for the predetermined time, The operation is stopped (step S8), and all processing is ended.

(6. Others)
In the above-described embodiment, a configuration including the swirling flow discharge hole 22 that discharges air in the tangential direction of one circumference on the inner circumferential surface of the column hole 21a2 or the tapered hole 21a1 has been described. However, as long as a swirling flow can be formed within the column hole 21a2 or the unclamping hole 21a3, the configuration is not limited to the configuration in which air is discharged in the tangential direction of one circumference.

Furthermore, although a configuration has been described in which the straight flow discharge hole 61 is used to switch between air discharge and coolant liquid discharge, the straight flow discharge hole 61 is used exclusively for air discharge, and the drawbar 60 has a hole exclusively used for coolant discharge. It may also be configured to be provided separately. In this case, the switching device 80 becomes unnecessary.

1; Spindle device, 8; Tool holder, 10; Housing (fixed part), 20; Spindle (rotating body), 21a; Tool mounting/detaching hole, 22; Swirling flow discharge hole, 30, 40; Bearing, 60; Drawbar, 61 Straight flow discharge hole, 70; Clamp unit, 80; Switching device, 81; Air supply source, 82; Coolant liquid supply source, 90; Control device

Claims (6)

A fixed part,
a cylindrical rotating body that is arranged within the fixed part so as to be rotatable relative to the fixed part around an axis, and a tool holder is removably attached to a tool attachment/detachment hole provided at one end in the axial direction;
a shaft that is disposed within the rotating body so as to be able to rotate integrally with the rotating body and to be movable relative to the rotating body in the axial direction, and clamps or unclamps the tool holder at one end in the axial direction; shaped drawbar;
Equipped with
The rotating body is provided with a swirling flow discharge hole that discharges air swirling around the axis in the tool attachment/detachment hole,
A spindle device, wherein the drawbar is provided with a straight flow discharge hole that discharges air that travels straight in the axial direction in the tool attachment/detachment hole. The spindle device according to claim 1, wherein the swirling flow discharge hole discharges air in a tangential direction of one circumference on an inner circumferential surface of the tool attachment/detachment hole. The spindle device according to claim 2, wherein openings of the swirling flow discharge hole are provided at at least two locations on one circumference of the inner peripheral surface of the tool attachment/detachment hole. The opening of the swirling flow discharge hole is provided at a position in front of the opening of the straight flow discharge hole in the discharge direction of the air discharged from the straight flow discharge hole. The spindle device described. The spindle device according to any one of claims 1 to 4, wherein a flow rate of air discharged from the straight flow discharge hole is larger than a flow rate of air discharged from the swirl flow discharge hole. The main spindle device according to any one of claims 1 to 5, wherein the main spindle device includes a switching device that switches air discharged from the straight flow discharge hole to coolant liquid.

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