JP3250430B2 - Multi-axis spindle head with bush plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-axis spindle head for drilling a machine tool such as a drilling head, and more particularly to a method for determining the positional accuracy of a drilling tool such as a drill. The present invention relates to a so-called carry-in bush plate type multi-axis spindle head provided with a bush plate for guiding the shaft.

[0002]

2. Description of the Related Art As this type of carry-in bush plate type multi-axis spindle head, for example, there is one having a structure shown in FIG. In this conventional structure, a bush plate 102 is disposed on the front side of a drilling head (multi-spindle head) 101 to which feed is provided by a feed unit (not shown). Is the slide bush 103
A plurality of guide bars 104 are provided so as to be slidable. The bush plate 102 is fixed to the tip of each guide bar 104, and the bush plate 102 is separated from the drilling head 101 by a compression coil spring 105 provided between the bush plate 102 and the drilling head 101. It is urged in the direction to be.

Here, the drilling head 101 has a number of spindles 106 as is well known, and each spindle 106 has a quick-change type adapter 107.
On the other hand, a guide bush 109 corresponding to each drill 108 is mounted on the bush plate 102. Each drill 108 is always guided to the guide bush 109 while feeding the drilling head 101 to continuously perform the drilling while moving forward and backward between the normal forward limit position and the normal retreat limit position. The guide bush 109 does not come off.

Therefore, according to the conventional structure, when the drilling head 101 is fed forward to perform a forward movement, the bush plate 102 is attached to a part of the processing jig 110 for positioning the work W to be processed. Is pressed, and thereafter, while the distance between the bush plate 102 and the drilling head 101 is gradually reduced, each of the drills 108 moves forward while being guided by the guide bush 109 to perform predetermined drilling on the work W. become.

That is, in the conventional structure as described above,
As shown in (A) ~ (C) of FIG. 9, drilling head 101 as long as drilling is being repeated by the drilling head 101 of the conventional forward limit position P ₁ and the conventional backward limit position P ₂ The bush plate 102 performs the forward / backward movement in response to the forward / backward movement. Then, the distance whereas a S _1, drilling head 101 is commonly retreat limit position between the drilling head 101 and the bushing plate 102 when drilling head 101 is in the conventional forward limit position P ₁ Drilling head 101 and bush plate 10 when in P ₂
2 is S ₂ (S ₁ <S ₂ ).

On the other hand, when a so-called tooling change is required, such as when the guide bush 109 of the bush plate 102 or the drill 108 itself needs to be replaced, the distance between the drilling head 101 and the bush plate 102 is commonly used. It is necessary to secure a work space necessary for exchanging the guide bush 109 and the drill 108 by making the work space larger than that used.

For this reason, conventionally, as shown in FIG. 9C, when the tooling change is performed, the bush plate 102 is temporarily fixed while being pressed against the counterpart processing jig 110, while the drilling head 101 is fixed. a stretch is retracted until the tooling change the retreat limit position P _3,
The distance S ₃ (S ₃ <S ₂ <S ₁ ) between the bush plate 102 and the drilling head 101 is as large as possible. Thus, the drilling head 10
By retracting the drill bush 1 to the tooling change retreat limit position P ₃ , each drill 108 on the drilling head 101 side can be completely removed from the corresponding guide bush 109 as necessary, and the guide bush 1
09 can also be removed from the bush plate 102.

[0008]

[Problems that the Invention is to Solve In such a conventional structure, even in a state where drilling head 101 is retracted to the tooling change retreat limit position P _3, drilling bushing plate 102 via a guide bar 104 Since it is assumed that the guide bar 104 is supported by the head 101, the guide bar 104 must be lengthened. Therefore, when the structure of a so-called carry-in bushing plate as shown in FIG. 8 is to be applied to a drilling head of a turret type machine tool in particular, it becomes difficult to apply the structure due to space restrictions. It has not been possible to bring the working head into a bush plate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. Particularly, the present invention has been made to reduce the length of the guide bar without impairing the original function of the bush plate, and to increase the number of drilling heads and the like in a turret type machine tool. An object of the present invention is to provide a structure capable of realizing a carry-in bush plate of a shaft spindle head.

[0010]

According to the first aspect of the present invention, a multi-axis spindle head provided with a plurality of drilling tools can be approached to and separated from the multi-axis spindle head. In addition, a bush plate provided with a plurality of guide bushes corresponding to each tool is arranged, and at the time of drilling, the work to be processed is positioned and fixed on the bush plate based on the advancing operation of the multi-axis spindle head. While pressing against the processing jig,
A multi-axis spindle head adapted to guide a corresponding tool with each guide bush, provided on the multi-axis spindle head so as to be parallel to the axis of each tool, and slidably guiding the bush plate. A plurality of guide bars to support, an elastic body for urging the bush plate in a direction away from the multi-axis spindle head,
In the processing jig, the leading end of the guide bar is inserted at the time of drilling, and the guide bar is abutted against the opening end face, so that the multi-axis spindle head feed direction of the bush plate with respect to the processing jig and its axis. A guide hole for regulating a position in a right angle direction, and a lock means provided in the processing jig, which locks and unlocks the guide bar with respect to the processing jig in a state where the tip of the guide bar is inserted into the guide hole. And a guide bar stopper provided on the side of the multi-axis spindle head to prevent the guide bar from coming off from the multi-axis spindle head and to release the guide bar.

At the time of a tooling change such as replacement of the tool or the guide bush, the locking means is locked while the multi-axis spindle head is moved forward, while the guide bar retaining means is released to release the bush. The multi-axis spindle head is configured to retreat while leaving the plate together with the guide bar on the processing jig side.

[0012] As described above, when a tooling change such as replacement of a tool or guide bush is performed, the multi-axis spindle head is independently moved backward while the bush plate and the guide bar are left on the processing jig side. Assuming that the normal retreat limit position of the multi-axis spindle head at the time of drilling and the retreat limit position of the multi-axis spindle head at the time of tooling change such as replacement of a tool or guide bush are the same, as in the invention described in Even if it is set, the multi-axis spindle head and the bush plate are better when the multi-axis spindle head is in the retreat limit position for tooling change than when the multi-axis spindle head is in the normal retreat position. And the distance between them increases.

As the tool for drilling, other than a drill, for example, a reamer or a counterbore tool can be used.

As a specific configuration of the locking means, for example, as described in claim 3, the locking means is provided around the guide hole and the tip of a guide bar inserted into the guide hole. Locking and unlocking the guide bar with respect to the processing jig by using the portion as a lock position, wherein the lock means includes a lock pin capable of engaging and disengaging from a groove formed at the tip of the guide bar;
And an actuator for moving the lock pin forward and backward.

Similarly, the guide bar retaining means includes:
As described in claim 4, a guide groove formed on the outer peripheral surface of the guide bar along the axial direction thereof, and a guide groove provided on a part on the multi-axis spindle head side and engaged with the guide groove. And a stopper pin which can be detached from the multi-axis spindle head and the guide bar within the length of the guide groove when the stopper pin is engaged with the guide groove. It is composed of

Further, the multi-axis spindle head is mounted as a drilling unit on an outer periphery of a turret head of a turret type machine tool.

Therefore, according to the first aspect of the present invention, at the time of a tooling change, the locking means is operated to lock while the multi-axis spindle head is moved forward, while the guide bar retaining means is released. Since the multi-axis spindle head is configured to retreat while the bush plate remains on the processing jig side together with the guide bar, the length of the guide bar is limited even if the length of the guide bar is short. The multi-axis spindle head can be retracted without being moved, and the multi-axis spindle head remains with the bush plate together with the guide bar on the processing jig side compared to when the multi-axis spindle head is at the normal retreat limit position. The distance between the multi-axis spindle head and the bush plate is larger when the To, it is possible to ensure the work space required for tooling change.

As a result, the shortening of the guide bar reduces the occupied space when the multi-axis spindle head is brought into a bush plate to form a bush plate. A bush plate can be easily brought in.

Further, even if the retreat limit position of the multi-axis spindle head and the service retreat limit position at the time of the tooling change are the same, the multi-axis spindle head is at the retreat limit position of the tooling change. In some cases, the distance between the multi-spindle head and the bush plate can be kept large, and the maximum stroke of the multi-spindle head can be reduced.

According to a third aspect of the present invention, a locking means is provided around the guide hole on the processing jig side, and the tip of the guide bar inserted into the guide hole is used as a lock position for the processing jig. If the guide bar is locked and unlocked, the structure can be simplified as compared with the case where a locking means is provided in another portion.

Further, as set forth in claim 4, a mechanism for permitting relative movement between the multi-axis spindle head and the guide bar within a predetermined stroke, a mechanism for preventing the guide bar from coming off from the multi-axis spindle head, and a mechanism therefor. By substantially sharing the mechanism for canceling, the structure can be further simplified.

[0022]

1 to 7 show a typical embodiment of the present invention, in which a multi-axis drilling head in a turret type machine tool is formed as a so-called carry-in bush plate. I have.

As shown in FIGS. 6 and 7, the turret type machine tool includes a feed unit 2 mounted on a base 1,
A column 4 mounted on a slide table 3 of the feed unit 2 and a 4-index type turret head 5 rotatably indexed around the column 4
And a processing jig 6 erected on the base 1 for positioning and fixing a work W to be processed. Four multi-axis type drilling heads 7A to 7D are mounted on the outer peripheral surface of the turret head 5, and any one of the drilling heads can be processed according to the type of the workpiece W to be processed or the processing content. The tool 6 is indexed to the machining position Q facing the tool 6. Then, for example, one of the four drilling heads 7A to 7D
A is configured as a carry-in bush plate type.

The turret head 5 is fed by a feed motor 8 of the feed unit 2, is indexed and rotated by the motor 9, and is further drilled at a machining position Q.
Each of the spindles is a motor 10 at the upper end of the column 4.
Is driven to rotate.

Details of the carry-in bush plate type drilling head 7A are shown in FIGS. 2 to 4. A plurality of spindles 12 are rotatably supported at the tip of a head body 11 of the drilling head 7A. Each spindle 12 has a quick-change type adapter 13
The drill 14 is mounted via the. An annular bush plate 15 is provided on the front side of the drilling head 7A.
The bush plate 15 is provided with a plurality of guide bushes 16 into which the drills 14 are inserted and guided.

A fixed bush 17 is mounted on the upper and lower portions of the support plate 11a on the head body 11 side of the drilling head 7A, and a guide bar 18 is slidably inserted into and supported by the bush 17 respectively. At the same time, the bush plate 15 is integrally connected to the tip of each guide bar 18.

More specifically, a guide groove 19 having a predetermined length is formed at the rear end (right end in FIG. 3) of the guide bar 18 inserted into the bush 17 along the longitudinal direction of the outer peripheral surface thereof. , The support plate 11 with respect to the guide groove 19.
The tip of the stopper pin 20 provided on the side a is engaged.
Thereby, the bush 17 and the guide bar 18 can be relatively moved in the axial direction within the range of the length of the guide groove 19.

On the other hand, a large-diameter flange portion 21 is integrally formed at the tip (left end in FIG. 3) of the guide bar 18, and the bush plate 1 is attached to the guide bar 18 itself.
The bush plate 15 inserted and supported by the guide bar 18 is fixed to the flange 21 by bolts 22. A bush 17 and a bush plate 15 are provided on the outer circumference of each guide bar 18.
Compression coil spring 2
3 are provided, and thereby the bush plate 15
Is always urged in a direction away from the drilling head 7A, but the forward limit position of the bush plate 15 with respect to the drilling head 7A is the guide groove 19 shown in FIG.
5 is restricted by the contact between the rear end face and the stopper pin 20 (the state shown in FIG. 5).

The stopper pin 20 is provided on the support plate 11a.
The stopper pin 20 is inserted and supported by a sleeve-like fixed cam 24 fixed to the end face of the stopper pin 20, and the stopper pin 20 is guided by a compression coil spring 25 interposed between the fixed cam 24 and the large diameter portion of the stopper pin 20. 19 is always urged in the direction of engagement.

A sleeve-shaped operation knob 26 also serving as a movable cam is integrally connected to a rear end side of the stopper pin 20 by a connection pin 27, and the fixed cam 24 and the operation knob 26 are connected.
Is a 45-degree inclined cam surface 24 formed on each end face
a and 26a are pressed against each other. And FIG.
3, the stopper pin 20 and the operation knob 26 are pulled toward the guide bar 18 by the force of the compression coil spring 25, and the tip of the stopper pin 20 is engaged with the guide groove 19, while the state shown in FIG. When the operating knob 26 is rotated 180 degrees while being pulled back against the force of the compression coil spring 25, the fixed cam 24 and the operating knob 26 are connected to the inclined cam surfaces 2 as shown in FIG.
The stopper pins 20 are configured to abut on flat surfaces other than 4a and 26a so that the stopper pin 20 comes out of the guide groove 19 as a result. As described above, the guide groove 19, the stopper pin 20, the fixed cam 24, the operation knob 26, and the like constitute the retaining means 40.

An annular work sheet plate 2 serving as a reference for positioning the work W is provided on a frame 27 of the processing jig 6.
8 is provided in a vertical posture, and a pair of work clamp mechanisms 29 are provided around the work sheet plate 28. This work clamp mechanism 29
The link 3 is connected to a hydraulic or pneumatic cylinder 30 and a piston rod 31 of the cylinder 30.
And a clamp lever 33 that performs a clamp and an unclamping operation by being rotationally displaced via the workpiece 2.
Are firmly positioned and clamped to the worksheet plate 28.

As shown in FIG.
As shown in FIG. 5, a pair of locating bushes 34 having guide holes 34a are mounted at positions corresponding to the guide bars 18, and the bush plate 15 is mounted on the processing jig 6 together with the drilling head 7A as described later. When the guide bar 18 is moved forward, the distal end portion 18a of each guide bar 18 is inserted into the locating bush 34, and the flange portion 21 is pressed against the opening end face of the locating bush 34, so that the bush plate for the processing jig 6 and the work W is pressed. Fifteen positions are determined.

A lock groove 35 is formed at the distal end 18a of each guide bar 18, while a hydraulic or empty bushing 34 into which the distal end 18a of the guide bar 18 is inserted is provided. A pressure cylinder 36 is mounted. A lock pin 37 is attached to the tip of the piston rod of the cylinder 36. Although the lock pin 37 is separated from the lock groove 35 during normal processing as shown in FIG. 3, the cylinder 36 is extended as described later. When operated, the lock pin 37 engages with the lock groove 35 to prevent the guide bar 18 from being pulled out from the locating bush 34. As described above, the lock means 41 is constituted by the lock groove 35, the cylinder 36, and the lock pin 37.

In the carry-in bushing plate type drilling head 7A configured as described above, if the drilling head 7A is indexed to the machining position Q shown in FIGS. Processing head 7A
Is until a machining start command is waiting in a conventional retreat limit position P ₂ shown in FIG. 5, it starts to move forward by the feed given when there is a machining start command by the feed unit 2 in FIGS.

[0035] In a state where drilling head 7A are in common retracted limit position P _2, the stopper pin 20 engages the guide groove 19 of the guide bar 18 as shown in FIG. 5 and its stopper pin The guide bar 18 from the bush 17 is brought into contact with one end surface of the guide groove 19.
Has been given a retaining. The guide bushing 16 is drilled head 7A as shown in FIG. 5 in a state in conventional backward limit position P _2, the tip of each drill 14 corresponding
It is inserted and guided. The distance between the drilling head 7A and bushing plate 15 when this is in the S _12.

When the drilling head 7A starts moving forward, the drills 14 mounted on the respective spindles 12 are simultaneously driven to rotate simultaneously, and the drilling head 7A is simultaneously driven.
3, the distal end portion 18a of the guide bar 18 is inserted into the locating bush 34 on the processing jig 6 side, and the flange portion 20 of the guide bar 18 is opened at the opening end face of the locating bush 34 as shown in FIG. , The forward movement of the bush plate 15 with respect to the processing jig 6 stops. Thus, the bush plate 15 is positioned with respect to the processing jig 6 and the workpiece W in the direction in which the drilling head 7A is fed and in the direction perpendicular to the axis thereof.
At this time, as shown in FIG. 3, the lock pin 37 is not engaged with the lock groove 35 of the distal end portion 18a of the guide bar 18.

In this state, the drilling head 7A is still
Continues to move forward, the compression coil spring 23 is gradually compressed, and each drill 14 is provided with a cutting feed while being guided by the guide bush 16 to perform a plurality of drilling operations on the work W at the same time. The drilling head 7A is stopped in a conventional forward limit position P ₁ shown in FIG. The distance between the drilling head 7A and bushing plate 15 when this is in the _{S 11 (S 11 <S 12} ).

Further, after the bush plate 15 is stopped and the drilling head 7A continues to move forward independently, the force applied to the processing jig 6 via the guide bar 18 is only the force of the compression coil spring 23. Therefore, the feed force of the feed unit 2 is not applied to the processing jig 6 via the guide bar 18.

[0039] When drilling head 7A as described above is advanced to the conventional forward limit position P _1, a predetermined drilling is completed at that point, until the drilling head 7A is customary retreat limit position P ₂ immediately shown in FIG. 5 The bush plate 15 returns to the initial state at the same time.

As described above, unless the drill 14 or the guide bush 16 is changed, the normal retreat limit position P ₂
Drilling head 7A between the conventional forward limit position P ₁ and it can be repeated drilling of multi-axis by reciprocating.

On the other hand, at the time of a tooling change in which the guide bush 16 or the drill 14 is exchanged, a gap that allows the drill 14 to be extracted from the corresponding guide bush 16 and allows the drill 14 to be extracted from the adapter 13 is drilled. Processing head 7A
And the bush plate 15.

[0042] In such a case, once to advance the drilling head 7A to conventional forward limit position P ₁ shown in FIG. 3 is stopped, the lock pin 37 by expansion operation of the cylinder 36 shown in FIG. 3 Lock groove 3 on guide bar side 18
5 is engaged. Further, the operation knob 26 is rotated by 180 degrees, and the stopper pin 20 is removed from the guide groove 19 as shown in FIG. On top of that, to retract the drilling head 7A to customary retreat limit position P ₂ shown in FIG. As a result, the lock pin 37 is fixed to the lock groove 3 on the guide bar 18 side.
To 5 in engagement with the guide bar 18 is locked retracted until drilling head 7A bush plate 15 and the guide bar 18 a processing jig 6 customary rearmost alone leaving the side position P ₂ I do.

As a result, the guide bar 18 is
From being withdrawn completely, drilling head 7A Despite the retracted normal to the same common retreat limit position P ₂ at the time of machining, the drill 14 or bushing between the drilling head 7A and the bushing plate 15 16 will be able to ensure the _{S 13 (S 11 <S 12} <S 13) large space made necessary conversion.

Then, at the stage when the exchange of the drill 14 or the guide bush 16 is completed, the drilling head 7A and the bush plate 15 may be returned to their original states by the reverse procedure.

[0045]

As is apparent from the above description, in the so-called carry-in bushing plate type multi-axis spindle head according to the first aspect, when the tool or the guide bush is replaced, the multi-axis spindle head is moved forward. In this state, the locking means is operated to lock while the guide bar retaining means is released, and the multi-axis spindle head is moved backward while the bush plate remains on the processing jig side together with the guide bar. There is no need to set the length of the guide bar in accordance with the maximum separation distance between the shaft spindle head and the bush plate,
The guide bar can be greatly shortened, and even if the normal retreat limit position of the multi-axis spindle head and the retreat limit position at the time of tooling change are the same as in the invention described in claim 2, the guide bar at the time of the tooling change is reduced. However, the distance between the multi-axis spindle head and the bush plate is increased, and a space necessary for a tooling change can be secured.

As a result, the size of the multi-axis spindle head can be reduced and the space can be saved by shortening the guide bar and shortening the maximum stroke of the multi-axis spindle head. Space constraints when bringing a multi-axis spindle head of a turret type machine tool into a bush plate are greatly eased, so that the multi-axis spindle head of the turret type machine tool can be easily brought into a bush plate. Become.

Further, as in the third aspect of the present invention, the leading end of the guide bar inserted into the guide hole is effectively used, and the leading end is used as a lock position by a locking means provided around the guide hole. By locking the guide bar, there is an effect that the structure can be simplified as compared with the case where the locking means is separately provided in other portions.

Further, according to the third aspect of the present invention,
The mechanism that regulates the relative movement stroke in the axial direction between the multi-axis spindle head and the guide bar, and the guide bar retaining means that controls the release of the guide bar and the release thereof are substantially shared. Also, the structure can be further simplified.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of the present invention, and is an explanatory cross-sectional view showing a state in which a drilling head is retracted to a normal retreat limit position during a tooling change.

FIG. 2 is a view showing one embodiment of the present invention, and is an explanatory side view showing a state in which a drilling head is advanced to a normal advance limit position.

FIG. 3 is an explanatory plan view of FIG. 2;

FIG. 4 is an explanatory sectional view taken along line AA of FIG. 2;

FIG. 5 is an explanatory sectional view showing a state where the drilling head is retracted from the state of FIG. 3 to a normal retreat limit position.

FIG. 6 is an explanatory side view of a turret type machine tool using the drilling head shown in FIGS.

FIG. 7 is an explanatory plan view of FIG. 6;

FIG. 8 is an explanatory sectional view showing a configuration of a main part of a conventional carry-in bush plate type drilling head.

FIG. 9 is an operation explanatory view of FIG. 8;

[Explanation of symbols]

5 Turret head 6 Processing jig 7A Drilling head (multi-axis spindle head) 12 Spindle 14 Drill (tool) 15 Bush plate 16 Guide bush 17 Bush 18 Guide bar 18a Tip 19 Guide groove 20 ... Stopper pin 23 ... Compression coil spring 34 ... Locating bush 34a ... Guide hole 35 ... Lock groove 36 ... Cylinder 37 ... Lock pin 40 ... Retaining means 41 ... Lock means P ₁ ... Normal forward limit position P ₂ ... Common use retreat position W ... Work

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B23B 49/00 B23B 39/16

Claims (5)

(57) [Claims] 1. A plurality of guide bushes which can be approached to and separated from the multi-axis spindle head and correspond to each tool are provided on the front side of a multi-axis spindle head provided with a plurality of drilling tools. During the drilling process, the bush plate is pressed by the guide bush while pressing the bush plate against a processing jig that positions and fixes the work to be processed based on the forward movement of the multi-axis spindle head. A plurality of guide bars provided on the multi-axis spindle head so as to be parallel to the axis of each tool, and slidably guiding and supporting the bush plate. An elastic body for urging the bush plate in a direction away from a multi-axis spindle head; At the time of drilling, the tip of the guide bar is inserted and the guide bar is abutted against the opening end face, and the bush plate is moved in the feed direction of the multi-axis spindle head relative to the processing jig and in the direction perpendicular to the axis thereof. A guide hole for regulating the position; a lock means provided in the processing jig, for locking and unlocking the guide bar with respect to the processing jig in a state where the tip of the guide bar is inserted into the guide hole; A guide bar retaining means provided on the multi-axis spindle head side for controlling the release of the guide bar from the multi-axis spindle head and releasing the guide bar. When the locking means is locked while the spindle head is moved forward, the guide bar retaining means is released. A multi-axis spindle head provided with a bush plate, wherein the multi-axis spindle head is moved backward while the bush plate and the guide bar remain on the processing jig side. 2. The multi-spindle spindle head is normally set at the same retreat limit position at the time of drilling and at the same retreat position at the time of exchanging a tool or a guide bush. A multi-axis spindle head provided with the bush plate according to claim 1. 3. The lock means is provided around a guide hole, and locks and unlocks the guide bar with respect to a processing jig by using a tip end of a guide bar inserted into the guide hole as a lock position. Wherein the lock means comprises a lock pin which can be engaged with and disengaged from a groove formed at the tip of the guide bar, and an actuator which moves the lock pin forward and backward. Item 7. A multi-axis spindle head comprising the bush plate according to item 1 or 2. 4. The guide bar retaining means is provided on a guide groove formed on an outer peripheral surface of the guide bar along an axial direction of the guide bar, and on a part of a multi-axis spindle head side, the guide groove being provided. And a stopper pin that can be engaged and disengaged, and when the stopper pin is engaged with the guide groove, the relative movement between the multi-axis spindle head and the guide bar is allowed within the length range of the guide groove. A multi-axis spindle head provided with the bush plate according to any one of claims 1 to 3. 5. The multi-axis spindle head is mounted as a drilling head on an outer periphery of a turret head of a turret type machine tool.
A multi-axis spindle head provided with the bush plate according to any one of (1) to (4).