JPH07108498B2 - Tool head interchangeable machine tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a tool head in which a tool head that can be indexed is made replaceable in a machine tool that advances and retracts the tool head with respect to a positioned workpiece. The replaceable work mechanism.

(Prior Art) Conventionally, as a machine tool for positioning and machining a work, for example, a machine tool as disclosed in JP-A-49-65575 is known. In this machine tool, since two or more tools are machined at the same machining station, two tool support members are provided, and these tool support members are selectively movable to the workpiece machining position. It aims to eliminate the lost time due to replacement.

On the other hand, in the case of such a machine tool, the number of tool heads is small,
Also, since multi-step processing at the same processing station or support for different models is limited, processing devices such as JP-B-63-20531 are also known. This processing device is configured to increase the number of processes at the same processing station, and selectively rotates a plurality of replaceable tools by an index motor to an operating position to perform different types of drilling, tapping, etc. It corresponds to a case where it is smoother to divide into a plurality of processing steps than simultaneous processing due to the arrangement relationship of the tool spindle because the plurality of processing steps or the processing parts of the work are close to each other.

(Problems to be solved by the invention) However, even in the case of the above-mentioned Japanese Utility Model Publication No. 63-20531, there is a limit to the number of processes that can be processed in the same station. It is necessary to add additional machining units, and for different types of workpieces with different shapes and machining positions, it is necessary to replace all tool heads of each machining unit. I had no choice but to change the state.

(Means for Solving the Problems) In order to solve the above problems, the present invention relates to a machine tool in which an index mechanism and a tool head are provided on a movable table that can move back and forth along a guide rail. A tool head is removably held by a carrier movable along the carrier, and the carrier is configured to be movable between the adjacent stockers. Then, a clamping mechanism was provided to separate the tool head of the carrier from the carrier and clamp it on the hollow shaft of the index mechanism. A connecting and positioning mechanism for connecting and positioning the tool head is provided on one end surface of the hollow shaft. Further, a clamp cylinder that is movable along the axial direction of the hollow shaft is provided on the outer periphery of the hollow shaft, and a clamp rod that engages with the clamp cylinder via a spring is provided. The carrier positioning pin was connected via.

On the other hand, in the tool head, a plurality of coupling positioning portions and index positioning portions are formed at equal intervals on the circumference, and engaging holes for carrier engagement are provided in the vicinity thereof, and clamp engagement is performed corresponding to the clamp rod position. I provided a piece.

Further, the machine tool is configured in a vertical type, and a balancer member is connected to the drive motor of the vertical type index mechanism via a bearing coaxial with the motor shaft.

(Operation) When it is necessary to replace the tool head, the carrier holding the tool head is moved toward the adjacent stocker, and instead, a different tool head of the carrier waiting in another stocker is received. Then, when indexing the tool head, the tool head is clamped on the index hollow shaft by the clamp mechanism and separated from the carrier. That is, the clamp cylinder provided on the outer periphery of the hollow shaft is operated, the clamp rod and the clamp engaging piece of the tool head are engaged to separate the tool head from the carrier, and the hollow shaft end face is connected to the coupling and positioning mechanism of the tool head. The connection positioning portion is engaged and positioned and held. At the same time, the carrier positioning pin associated with the clamp rod positions the carrier separated from the tool head.

On the other hand, when this machine tool is used vertically, the balance of the index mechanism unit, which is a heavy load, is achieved by the balancer member connected to the drive motor of the index mechanism. In other words, support to pull up.

(Example) The Example of the tool head exchange type machine tool of this invention is described based on the accompanying drawing.

1 to 3 are overall views showing an embodiment in which the machine tool of the present invention is configured as a vertical type. FIG. 1 is a side view, FIG. 2 is a front view, and FIG. 3 is a plan view. 4 and 5 are enlarged views showing the internal structure of the main part. FIG. 4 is a side view, FIG. 5 is a front view, and FIG. 6 is a side view of the internal structure of the index mechanism. FIG.

First, an embodiment in which the machine tool of the present invention is configured as a vertical machine tool will be described.

As shown in FIGS. 1 to 3, the vertical machine tool includes a plurality of processing units 2 arranged in parallel for performing multi-step processing on a relatively small work W positioned on a pallet 1. In preparation for this, a stocker 3 is linearly arranged between the processing units 2. Then, in these stockers 3, a tool head 4 different from the tool head 6 of a lifting table 10 as a movable table which will be described later is held by a carrier 5 and stands by.

The processing unit 2 is configured to perform processing on a plurality of positions of the work W at the same station, or to perform different types of processing. The arm 8 is projected from the upper portion of the column 7 toward the front, and is perpendicular to the front surface. A guide rail 9 is provided, and a lift table 10 that engages with the guide rail 9 can be moved up and down by a lift motor 11 on the arm 8. That is, as shown in FIG. 6, the ball screw 13 connected to the drive shaft of the lifting motor 11 is screwed into the screwing portion 10a of the lifting table 10.
Screw and rotate the ball screw 13 to raise and lower the table.
I am trying to move 10 up and down.

On the other hand, a spindle drive motor 14 for driving the tool spindle shown in FIG. 1 is provided at the tip of the arm 8, and a spindle shaft 15 extending downward from the drive motor 14 is vertically moved integrally with the lifting table 10. The main body casing 16 can be pierced to be connected to the tool head 6 on the carrier 5.

Further, a balancer cylinder unit 19 as shown in FIG. 4 is mounted as a balancer member on the further tip side of the arm 8, and a cylinder shaft 20 extending downward from the balancer cylinder unit 19 is integrated with the main body casing 16. On the same axis as the rotating shaft of the index motor 21
It is connected through a bearing.

The tool head 6 of the lifting table 10 and the tool head 4 of the stocker 3 are exchangeable.

That is, each tool head 4, 6 has a respective carrier 5
And each carrier 5 is supported by the carrier support 22 of the stocker 3 shown in FIG. 4 or the carrier support 23 of the lifting table 10. The carrier support 23 has the same structure as the carrier support 22. Has been formed. That is, the carrier support 22 of the stocker 3 is formed with a guide groove 22a extending in the direction perpendicular to the paper surface of FIG. 4, and the traveling roller 25 of the carrier 5 is fitted in the guide groove 22a. That is, carrier 5
Is movable horizontally along this guide groove,
Further, the guide groove 22a is formed by the carrier support portion 2 on the lifting table 10 side.
It is configured to communicate with the guide groove provided in 3 when the lifting table 10 is lifted. (In FIGS. 4 and 5, the lift table 10 of the processing unit 2 is lowered.) That is, the carrier 5 is movable between the lifted lift table 10 and the stocker 3.

In the middle of the carrier 5, the arm 5a protruding forward is provided.
A tool head support pin 26 is projectingly provided on the tip. The tool head support pin 26 is used for the tool head 4 or 6 described later.
4 are provided in a pair in the front and back direction of the paper surface of FIG. At the lower end of the carrier 5, a carrier receiving roller 27 and a head receiving roller 28 are provided. The carrier receiving roller 27 is the carrier supporting member 22 or the carrier supporting portion of the lifting table 10 described above.
23 It abuts on a guide plate 29 fixed to the lower end and rolls along the guide plate 29 when the carrier 5 moves, and also prevents the carrier 5 from tilting and keeps it in an upright position. On the other hand, the head receiving roller 28 is a tool head 6 described later.
When holding the tool head 6, the tool head 6 is held in an upright posture so that the tool head 6 does not tilt by coming into contact with one end of the peripheral edge of the tool head 6.

On both sides of the carrier 5, connecting hooks 31 as shown in FIG. 5 are provided. The carrier 5 of the lifting table 10 and the carrier 5 of the stocker 3 which are adjacent to each other can be engaged and disengaged with each other, and when the carrier 5 on the lifting table side descends due to the lowering of the lifting table 10, the stocker 3 is connected.
The staggered tooth shape is such that the engagement with the side carrier 5 is released. (It should be noted that the meshed state is as shown in the plan view of FIG. 8.) Then, of the carriers 5 of the stocker 3 arranged at predetermined intervals, one side end has a tool as shown in FIG. The head shift cylinder unit 32 is connected. Therefore, when the lifting tables 10 of all the processing units 2 are moved upward, the carrier 5 of the stocker 3 and the carrier 5 of the lifting table 10 are connected by the connecting hooks 3 and are in a straight line, and the carrier 5 of the shift cylinder unit 32 is moved. The tool heads 4 on the carrier 5 are simultaneously shifted by the reciprocating motion.

Next, the tool head 6 will be described with reference to FIGS. 6 and 7. Incidentally, FIG. 7 is a plan view of the upper surface of the tool head.

The tool head 6 of the present embodiment is provided with four tool spindles 35 in four different areas on the lower surface thereof and has a circular shape. That is, the mounting surface of the group of tool spindles 35 on the lower surface is divided into four in the circumferential direction, and the four tool spindles 35 attached to each divided surface are sequentially indexed by an index mechanism described later to process the work. Become. On the upper surface of the tool head 6, four projecting portions 36 are provided along the outer peripheral edge portion. Then, in the projecting portion projecting toward the outer peripheral direction of the projecting portion 36, an engaging hole 37 for inserting the tool head support pin 26 provided in the carrier arm portion 5a described is provided.
Is provided. Of the engaging holes 37 provided in each of the four protruding portions 36, the two engaging holes 37 in either one of the two directions (the left and right direction in FIG. 7) are used as a pair of tools of the carrier 5. The head support pins 26 are engaged and supported.

Further, a head coupling positioning groove 38 and a head index positioning groove 39 are linearly provided in the protruding portion along the radial direction. The head connection positioning groove 38 is formed in a groove shape by projecting a pair of engagement protrusions 40 from both sides, and is also capable of engaging with the engagement positioning protrusions 54 at four locations on the lower surface of the index hollow shaft 47 of the index mechanism described later. .

The head index positioning groove 39 is for positioning the tool head 6 after indexing, and the lower end of the index positioning rod 63 of the index mechanism described later can be engaged with the index positioning groove 39 at any one position. The lower end of the rod 63 is fitted.

Further, a pair of arc-shaped clamp engaging pieces 42 are provided on the inner upper end of the protruding portion 36. This clamp engagement piece 42,
When the tool head 6 is separated from the carrier 5 and pulled up, a clamp rod 50 described later is engaged.
The mounting position is open on the shift direction side (vertical direction in FIG. 7) when the tool head 6 shifts together with the carrier 5.

Further, at the center of the upper surface of the tool head 6, as will be described later, a serration clutch portion 44 for coupling with the spindle shaft 15 is formed.
Is provided.

On the other hand, on the outer peripheral portion of the lower side of the tool head 6, a supporting portion 43 is provided so as to project in the outer peripheral direction in correspondence with the position of the projecting portion 36. The head receiving roller 28 comes into contact. That is, the tool head 4 is held on the carrier 5 by the two engaging holes 37 on the upper surface, and the two bearing portions 43 on the lower end side are supported by the head receiving roller 28 so as not to be tilted. .

Next, the index mechanism will be described with reference to FIG.

A Geneva gear 45 is provided above the main body casing 16, and a crank member 46 for pitch-rotating the Geneva gear 45 is connected to the output shaft of the index motor 21. That is, the pin on the upper surface of the crank member 46 shown in FIG.
49 enters the radial groove of the Geneva gear 45, and one rotation of the crank member 46 causes the Geneva gear 45 to rotate by 90 degrees in pitches.

Below the Geneva gear 45, the spindle shaft 15 of FIG.
There is provided an index hollow shaft 47 that allows the shaft to pass therethrough and is housed in the casing 16. The hollow shaft 47 and the Geneva gear 45 are connected by a bolt 48.

A flange portion 47a is provided on the outer periphery of the lower end portion of the hollow shaft 47. Further, four clamp rods 50 are provided on the flange portion 47a so as to be slidable in the vertical direction, and the lower end side of the clamp rod 50 has the clamp engaging pieces 42 of the tool head 6 described above. It has a notch for hooking. As shown in FIG. 7, the notch has a semicircular cross section so as not to interfere with the shift direction (up and down in FIG. 7) when the tool head 6 is replaced.

Further, the upper end side of the clamp rod 50 penetrates a flange portion 51a of a clamp cylinder 51 described below and engages with the flange portion 51a.

That is, the clamp cylinder 51 is slidably fitted on the outer periphery of the hollow shaft 47 and is vertically movable by operating pressure such as air pressure, and the flange portion 51a at the lower end of the clamp cylinder 51 is free to move. The upper end of the penetrating clamp rod 50 is connected to an annular disc 52. The annular disc 52 can move freely along the outer peripheral surface of the clamping cylinder 51, and a spring 53 is interposed between the annular disc 52 and the upper surface of the flange 51a of the clamping cylinder. .

On the other hand, a positioning mechanism is provided on the lower surface of the hollow shaft 47. That is, four connection positioning protrusions 54 are provided for engaging with the grooves 38 between the head connection positioning engagement protrusions 40 on the upper surface of the tool head 6 described above. (See FIG. 4) Therefore, the clamp rod 50 is lifted via the spring 53 by the upward movement of the clamp cylinder 51, and the notch in the lower part of the clamp rod 50 is hooked on the clamp engaging piece 42 on the upper surface of the tool head 6. Then, the tool head 6 on the carrier 5 is separated from the carrier 5 and pulled up. Also at this time,
The serration portion formed at the lower end of the spindle shaft 15 and the serration clutch portion 44 at the center of the upper surface of the tool head 6 mesh with each other. At the same time, the connection positioning projection 54 projecting from the lower surface of the hollow shaft 47 meshes with the head connection positioning groove 38 on the upper surface of the tool head 6 to clamp the tool head 6. Further, at this time, the separated carrier 5 is positioned, and its mechanism will be described below. As shown in FIG. 6, a bearing member 56 fixed to the main body casing 16 side is provided in the vicinity of the annular disc 52 described above, and one end side of the bearing member 56 is supported by the bearing member 56 at the peripheral portion of the annular disc 52. An intermediate shaft 57 to be engaged is provided. The engaging portion 57a is slidable with respect to the peripheral edge so as to allow the rotation of the annular disc 52. The other end of the intermediate shaft 57 determines the carrier position via a link member 58 and is connected to a pin 59. The middle part of the link member 58 is pivotally attached to the main body casing 16 side so that the link member 58 can swing. Therefore, the carrier positioning pin 59 descends and the lower end of the link rod 58 rises when the clamp rod 50 moves upward due to the upward movement of the clamping cylinder 51. It will be inserted into the positioning hole 60 provided in the carrier 5. That is, the position of the carrier 5 is fixed.

The tool head 6 thus clamped on the lower surface of the hollow shaft 47
Can be indexed separately from the carrier 5, but a mechanism is provided for accurately positioning the tool head 6 when indexing is completed and opening it during indexing.

That is, as shown in FIG. 4, a cam 61 is provided on the back surface of the crank member 46 that drives the Geneva gear, and one end side of the link member 62 that abuts on the cam 61 and swings is urged downward. Is connected to the index positioning rod 63. And the lower end protrusion 63a of this positioning rod 63
Engages with the head index positioning groove 39 of the tool head 6 described above. Further, the cam 61 is positioned so as to push down the contact point of the link member 62 immediately before the crank member 46 rotates and the pin 49 meshes with the Geneva gear 45. Therefore, when the tool head 6 makes an index rotation, the tool head 6 is rotated. 6 is released from this positioning rod 63. Then, when the index rotation is completed, the positioning rod 63 descends again, and the lower end protrusion 63a engages with the head index positioning groove 39 of the tool head 6.

The position of the index positioning rod 63 is the 8th position.
It is the position shown in the figure, and FIG. 8 is an explanatory view in plan view showing the positional relationship between the carrier support and the carrier.

On the other hand, a spline is formed on the outer periphery of the upper portion of the spindle shaft 15, and this spline portion is spline-coupled to the motor shaft of the upper spindle drive motor 14 and can be retracted into and out of the drive motor 14.

The cylinder shaft 20 of the balancer cylinder unit 19 described above is coaxially connected to the motor shaft of the index motor 21 via a bearing 65 as shown in FIG. Therefore, even if the crank member 46 rotates together with the motor shaft, the cylinder shaft 20 will not be rotated together.
The balancer cylinder unit 19 is pressed only in the direction that supports the force pulling the cylinder shaft 20 downward.

Further, this balancer cylinder unit 19 may use a spring.

The outline of the operation of the tool head exchange type machine tool configured as described above is as follows.

When the work W on the pallet 1 is transferred to the processing unit 2 and positioned, the lifting table 10 which has already clamped the tool head 6 and is standing by above is lowered by the lifting motor 11. Then, the machining is performed by the tool spindle 35 indexed in advance.

When the machining is completed, the next tool spindle 35 is indexed. That is, when the elevating table 10 is raised, the index motor 21 is operated to rotate the Geneva gear 45 and the hollow shaft 47 by 90 degrees by the crank member 46 and rotate the clamped tool head 6 by 90 degrees. At this time the crank member
The index positioning rod 63 that engages with the tool head 6 is temporarily pulled up by the cam 61 on the lower surface of the tool 46, and is engaged again when the index is completed.

In this way, when the four process steps are completed by the four tool spindles 35 of the tool head 6, if necessary, the tool head 4 of the stocker 3 waiting next time continues to perform the process. That is, the lifting table 10 is raised and the sixth
The clamping cylinder unit 51 shown in the figure is lowered to bring the tool head 6 into an unclamped state. Therefore, the tool head support pin 25 of the carrier 5 engages with the engagement hole 37 of the tool head 6, and the carrier positioning pin 59 moves upward,
The engagement between the lifting table 10 and the carrier 5 is released.

Then, the carrier 5 in the stocker 3 is pushed into the elevating table 10 by the movement of the shift cylinder unit 32 shown in FIG. 2, and the carrier 5 in the elevating table 10 is pushed into the opposite stocker 3 and then the Machining with different types of tool heads 4 is performed in the same procedure.

Next, an embodiment in which this machine tool is a horizontal type will be described with reference to FIGS. 9 to 16. Fig. 9 is a side view of the horizontal machine tool, Fig. 10 is the same plan view, and Fig. 11 is the same rear view.
FIG. 12 is an enlarged detailed side view of FIG. 9, FIG. 13 is an enlarged detailed plan view of FIG. 10, and FIG. 14 is a sectional view showing an internal structure in plan view.

This horizontal machine tool has almost the same configuration as the vertical machine tool described above, and the following description will be given mainly focusing on the difference from the vertical machine tool.

That is, as shown in FIGS. 9 to 11, a plurality of processing units 102 mounted on the base 107 are arranged in parallel, and a stocker 103 is provided between the processing units 102 on the same straight line. There is. Then, the work W supported by the pallet 101 is positioned on the front surface side of the processing unit 102, and on the opposite side (left side in FIG. 9) of the work of the pallet 101, processing (not shown) is performed. The units are provided symmetrically so that both the left and right sides of the work W can be processed at the same time. For this reason, an opening is provided on the left side surface of the pallet 101 in FIG. 9 in accordance with the processed portion of the work W.

The processing unit 102 includes a support arm 108 provided on the back side of the base 107 and a horizontal movement motor 111 attached to the support arm 108. By driving the horizontal movement motor 111, the movable table 110 is moved to the guide rail 109. It is reciprocally movable horizontally.

Therefore, the main body casing 116 integrally formed with the movable table 110, the index motor 121, and the tool head 106.
And the like move forward and backward with respect to the work W.

Further, the index motor 121 is not provided with the balancer cylinder unit 19 unlike the vertical machine tool.

On the other hand, the carrier 105 that engages with the guide groove of the carrier support portion 123 is allowed to travel in the guide groove by the traveling roller 125 shown in FIG. 16, and the traveling roller in the case of a vertical machine tool.
I am trying to use a different roller than 25. The 16th
The figure is a half-cut longitudinal sectional view showing the relationship between the carrier and the carrier support. On the other end side of the carrier 105, the carrier receiving roller 127 of FIG. 12 travels on the guide plate 129, which is the same as in the vertical type.

Further, as shown in FIG. 14, the notch of the clamp rod 150 that engages with the clamp engaging piece 142 of the tool head 106 has a slightly different shape from that of the vertical type, and the clamp engaging piece 142 Is shaped so that it can be held from both sides. That is, the tool head 106 can be moved left and right in conjunction with the left and right movement of the clamping cylinder 151. Therefore, the tool head 106 has a hollow shaft 147.
When the clamping cylinder 151 is actuated from the state of being clamped at, the tool head 106 moves to the left, the tool head support pin 126 is engaged with the engagement hole 137 of the tool head 106, and at the same time, the lower outer circumference of the tool head is It is supported by the head receiving roller 128 shown in FIGS.

As described above, the difference from the vertical machine tool is mainly described, but the other configurations are the same as those of the vertical type machine tool.

In the figures, the vertical type 1 corresponds to the horizontal type 101, 2 to 102, and 63 to 163.

Further, in the case of such a horizontal type, both sides of the work W can be simultaneously processed as described above, so that a more rapid work is possible.

(Effects of the Invention) As described above, the tool head exchange type machine tool of the present invention is
A stocker is provided adjacent to the machining units of the machining stations at various locations, the tool head is held by a carrier that can move between the machining units and the stocker, and the machining unit is provided with an index mechanism. The number of processing steps that can be processed is significantly increased, and the work loss time can be reduced. For this reason, it is particularly convenient when handling various kinds of workpieces having different shapes or processing positions, and it is possible to smoothly and swiftly process workpieces that require multi-step machining.

[Brief description of drawings]

1 to 8 show an embodiment in which the machine tool of the present invention is configured as a vertical machine tool. FIG. 1 is a side view of the entire apparatus, FIG. 2 is the same front view, and FIG. 3 is the same plane. FIGS. 4, 5 and 5 are enlarged views showing the internal structure of the index mechanism. FIG. 4 is a side view, FIG. 5 is a front view, and FIG. 6 is an enlarged view of the index mechanism part from a side view. Fig. 7 is a plan view showing the upper surface of the tool head, Fig. 8 is a plan view showing the relationship between the carrier and the carrier support, and Figs. 9 to 16 show an embodiment in the case of a horizontal machine tool. , Fig. 9 is a side view of the whole device,
10 is a plan view of the same, FIG. 11 is a rear view of the same, FIG. 12 is a detailed side view of an enlarged view of FIG. 9, FIG. 13 is a detailed plan view of an enlarged view of FIG. 10, and FIG. 14 is a plan view. Sectional view showing the internal structure by
FIG. 15 is a rear view showing the end face of the tool head, and FIG. 16 is a half-cut longitudinal sectional view showing the relationship between the carrier and the carrier support. In the figure, 1 is a pallet, 2 is a processing unit, 3 is a stocker, 4 is a tool head, 9 is a vertical guide rail, 10 is a lift table as a movable table, 11 is a lift motor, and 14 is a lift motor.
Is a spindle drive motor, 15 is a spindle shaft, 19 is a balancer cylinder unit, 21 is an index motor, 26
Is a tool head support pin, 31 is a connecting hook, 32 is a shift cylinder unit, 35 is a tool spindle, 37 is an engagement hole, 38
Is a head connection positioning part, 42 is a clamp engaging piece, 47 is a hollow shaft, 47a is a flange part, 50 is a clamp rod, 51 is a clamping cylinder, 59 is a carrier positioning pin, 101 is a pallet, 102 is a processing unit, 103 Is a stocker, 105 is a carrier, 106 is a tool head, 107 is a base, 109 is a guide rail, 110 is a movable table, 125 is a traveling roller, 125 is a traveling roller, 126 is a tool head support pin, 127 is a carrier receiving roller, and 151 is a clamping cylinder. , W indicates a work.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-61-270008 (JP, A) JP-A-63-102806 (JP, A) JP-A-63-221911 (JP, A)

Claims (4)

[Claims] 1. A machine tool in which an index mechanism and a tool head are provided on a movable table that can move back and forth along a guide rail. The machine tool holds the tool head detachably and guides the movable table. A carrier movable between the groove and the guide groove of the adjacent stocker, and a clamp mechanism for separating the tool head from the carrier and clamping the hollow shaft of the index mechanism are provided, and a tool is provided on one end surface of the hollow shaft. A tool head exchange type machine tool, which is provided with a connecting and positioning mechanism for connecting and positioning the heads. 2. A clamp cylinder, which is movable along the axial direction of the hollow shaft, is provided on the outer periphery of the hollow shaft, and a link mechanism is provided on the clamp rod that engages with the clamp cylinder via a spring. The tool head exchange type machine tool according to claim 1, wherein the carrier positioning pin is connected through the carrier positioning pin. 3. The tool head is formed with a plurality of coupling positioning portions and index positioning portions at equal intervals on the circumference, and is provided with engaging holes for engaging with the carrier in the vicinity thereof. The tool head exchange type machine tool according to claim 2, wherein a clamp engagement piece is provided corresponding to a position of the clamp rod. 4. The machine tool is configured as a vertical type, and a balancer member is connected to a drive motor of an index mechanism of the vertical type machine tool via a bearing coaxial with the motor shaft. The tool head exchangeable machine tool according to item 1.