JPH0464801B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention provides a pusher for pressing down a drawbar housed inside the hollow main shaft by arranging it on the side of the hollow main shaft. The present invention relates to a machine tool in which a drive motor can be directly connected to one end of the machine tool, thereby improving power transmission efficiency and stopping accuracy of the main spindle.

Conventional technology In machine tools such as machining centers (MC) that can perform various types of processing such as thread cutting and drilling on workpieces, tools such as taps and drills are securely attached to and removed from the tool attachment part of the spindle. Means are provided to do so. For example, Utsukai 55-
As in the machine tool disclosed in Publication No. 151435, a drawbar with a tool mounting portion formed at one end is slidably inserted into the main spindle, and a tool is firmly mounted in the tool mounting portion of the drawbar. The configuration is known. Further, a mechanism for forcibly pushing down the drawbar in the axial direction is provided at the top of the main shaft, and by pushing down the drawbar by the mechanism,
The tool is removed from the tool mounting section.

Problems to be Solved by the Invention In the machine tool having the above-mentioned configuration, a mechanism for pushing down the drawbar is provided above the main spindle, so the main spindle is directly connected to a drive source such as a motor or a speed reducer that drives the main spindle. I can't. For this reason, a pulley is disposed at an appropriate position on the main shaft, and the main shaft is rotationally driven by being connected to a drive motor via a belt wrapped around the pulley.
In this case, when power is transmitted by the pulley and the belt, "slip" inevitably occurs, which causes a change in the rotational speed of the main shaft, resulting in a reduction in machining accuracy. It also has the disadvantage that the precision in stopping the main shaft at a predetermined position is reduced due to the above-mentioned "slip". Furthermore, with the belt drive system,
There is a risk of bending deformation to the main shaft. Therefore,
It is necessary to strengthen and reinforce the supporting structure of the main shaft, but this also makes the structure complicated and increases costs.

Purpose of the Invention The present invention has been proposed in order to suitably solve the above-mentioned drawbacks inherent in the machine tool, and the tool mounting/removal operations are performed from the top of the spindle as before. It is an object of the present invention to provide a machine tool in which the main spindle and a power source can be directly connected to achieve efficient power transmission to the main spindle, and the machining accuracy of the main spindle can be improved. do.

Means for Solving the Problems In order to overcome the above problems and achieve the intended purpose, a machine tool according to the present invention rotatably supports a hollow main shaft having a tool mounting portion at one end, and a a spindle head movably supported by a frame along an axis; a feed motor for moving the spindle head along the axis; and a feed motor provided on the spindle head and extending coaxially with the axis of the hollow spindle. a main shaft driving means having an output shaft and connecting the output shaft to the hollow main shaft for rotationally driving the hollow main shaft; By the action of the means, a tool clamping member which always clamps the pull stud of a tool mounted on the tool mounting portion of the hollow spindle, and one end connected to the tool clamping member and the other end accommodated in the center hole of the hollow spindle. a slot formed in the hollow main shaft so as to face the other end of the drawbar and extend along the axis; and a slot fixed perpendicularly to the other end of the drawbar;
a pin whose free end extends outward from the hollow main shaft through the slot; a pressing body movably supported by the main shaft head and having an engaging portion capable of engaging with the pin; and the pressing body. interlocking means provided between the tool and the frame and causing the pushing body to push the pin against the urging means in conjunction with the movement of the spindle head to the tool exchange position by the feed motor; It is characterized by being configured.

Embodiments Next, preferred embodiments of the machine tool according to the present invention will be described below with reference to the accompanying drawings. FIG. 10 shows an overall schematic configuration of a machine tool 10 according to an embodiment, and this machine tool 10 includes:
Spindle head 1 rotatably supports hollow spindle 26
8 is supported on the frame 16 so as to be able to move up and down in a reciprocating manner, so that required cutting can be performed on the workpiece. A tool holding member 66 for removably holding the tool 20 is disposed in a tool mounting portion 52 provided at the lower end of the main shaft 26, and a tool support base 24 is supported on the frame 16 so as to be movable up and down. A disk-shaped tool magazine 22 in which a plurality of tool grippers 96 are arranged radially is pivotally supported on the tool support base 24 so as to be rotatably indexable. As will be described later, the tool gripper 96 is biased by the first cam 162 and the first crank 28, and can grip and release the tool 20 provided at the tip of the main shaft 26.

(Regarding the spindle head and its elevating system) As shown in FIG. 10, a hollow box-shaped frame 16 is horizontally arranged and fixed in front of a column 14 that is placed upright on a base 12, and rotatably supports the spindle 26. A spindle head 18 is disposed within this frame 16 so as to be movable up and down. That is, as shown in FIGS. 5 and 6, a guide rail 36 is installed perpendicularly through a screw 34 to each longitudinal end surface of a pair of long column members 32, 32 arranged upright in parallel with the front surface of the column 14. It is fixed. Then, spindle head 1
By fitting a pair of left and right sliding pieces 38, 38, which are arranged in a pair above and below at the rear of the spindle head 8, into the guide rails 36, 36 in a corresponding manner, the spindle head 1
8 can be raised and lowered perpendicularly to the frame 16.

Further, a support plate 39 is horizontally fixed to the bridge between the tops of the pair of long column members 32, 32, and an AC servo motor 40 with a built-in rotary encoder 42 is mounted.
is arranged upright on the support plate 39. The rotating shaft 41 of the servo motor 40 is fixed to a ball screw 44 via a coupling 43, and as can be seen from FIG. Extending. Further, as shown in FIGS. 1 and 6, a nut 46 is horizontally fixed to the protrusion on the rear surface of the spindle head 18 via a bolt 48, and the ball screw 44 is inserted and screwed into this nut 46. By rotating the AC servo motor 40, the ball screw 44 rotates in a desired direction, giving linear motion to the nut 46, and the spindle head 18 is vertically driven up and down by a predetermined stroke. Ru.

The area in which the spindle head 18 moves up and down is, as shown in FIG. The automatic exchange area B is divided into an automatic exchange area B where a series of attachment/detachment exchange operations of the tool 20 with respect to the spindle 26 are performed. In the process of the spindle head 18 moving upward in the automatic exchange area B, three inflection points appear (described later) that cause a series of tool exchange operations to be performed.
Incidentally, the spindle head 18 shown in FIGS. 1, 5, and 10 finishes machining the workpiece and rises to the upper limit of the machining operation area A (lower limit of the automatic exchange area B), and then starts the next machining. It is in a state where it is waiting for either a command or a tool change command.

(Regarding the tool attachment structure of the spindle) As shown in FIG.
A hollow cylindrical main shaft 26 is connected to upper and lower bearings 50, 50.
It is rotatably vertically supported through the shaft. A motor 56 having a speed reducer 58 is disposed upright on the top of the main shaft head 18, and its output shaft 60 is connected to the upper end of the main shaft 26 via a coupling 54. Thereby, the power from the motor 56 is efficiently transmitted to the main shaft 26, and stable rotation of the main shaft 26 can be obtained. Moreover, by connecting the motor 56 and the main shaft 26 only through the reducer 58, the accuracy in stopping the main shaft 26 can be improved.

Further, a tool mounting portion 52 consisting of a truncated conical opening is formed at the lower end of the main shaft 26, and the arbor 6
2 can be detachably attached to the tool 20. A pull stud 64 is provided at the rear end of the arbor of the tool 20, and the hollow main shaft 26
The tool 20 is fixed to the main shaft 26 by clamping the pull stud 64 with a tool clamping member 66 slidably inserted therein. The tool holding member 66 is a known collet having a configuration in which the neck portion of the pull stud 64 is surrounded by a plurality of balls 68. The pull stud 64 can then be clamped and released.

As shown in FIG.
Drawbar 7 whose upper end is inserted and fixed into the vertical hole of 0
6 hangs down along the central axis of the main shaft 20, and its lower end is connected to the top of the tool holding member 66. At the position where the plug 70 is disposed on the main shaft 26, oval slots 74, 74 are formed facing each other (FIG. 1), and both ends of a pin 72 inserted perpendicularly into the plug 70 are inserted into the pair of slots 74, 74 facing each other. It extends horizontally outward of the main shaft 26 through slots 74, 74 (FIG. 6). As shown in FIG. 1, when the tool 20 is attached to the tool attachment portion 52, the step portion formed below the hollow portion of the spindle and the washer 80 provided at the lower end of the plug 70
A group of disc springs 78 are elastically compressed and inserted between the two, and a draw bar 76 is inserted through and extends through the center of the large number of disc springs 78. And this disc spring 78
The elasticity of the plug 70 normally pushes the plug 70 and holds it in place, and also elastically pulls up the tool clamping member 66 to ensure that the pull stud 64 is clamped.

As shown in FIGS. 1 and 6, above the orthogonal pin 72 extending outward from the main shaft, a fork portion 81 formed into two at the tip of the second crank 30, which will be described later, faces closely. , the pin 72 is pressed and biased by the operation of the crank 30, and the drawbar 7
6 is lowered. That is, when the orthogonal pin 72 is pressed downward by the cam operation of the second cam 188 and the second crank 30, which will be described later, the draw bar 76 descends in the axial direction, lowering the tool holding member 66, and the ball 68 Release the pressure on the pull stud 64. Therefore, the tool 20 is in a state where it can be released from the tool mounting portion 52. In FIG. 1, reference numeral 83 indicates a cutting tool such as a drill or tap that is detachably attached to the tool 20.

(About the tool support stand) Next, on the frame 16, there is a tool magazine 22
A tool support stand 24 that rotatably supports the main shaft 26 is supported so as to be movable in the axial direction of the main shaft 26. In Figures 1 and 6, frame 1
Support plates 82, 82 are provided on the opposite side walls 16a, 16b of 6.
is installed horizontally, and a round bar-shaped guide rail 84 is inserted into the vertical through hole bored at the appropriate position of each horizontal support plate 82.
is slidably inserted. Further, as shown in FIG. 1, a pair of left and right horizontal support plates 86 extend from below the frame 16.
The guide rail 84 is inserted into the vertical through hole drilled in 6.
is slidably inserted. The upper and lower ends of the guide rails 84 (there are two as shown in FIG. 6) are connected to a support plate 91 provided on a horizontal top plate 88 bridged over the top of the tool support stand 24 and a support plate provided on the bottom. 89, respectively. Therefore, the tool support stand 24 can be moved up and down with respect to the frame 16 by sliding the guide rail 84 with respect to the horizontal support plates 82 and 86.
The cam 162 and the first crank 28 are moved up and down by a predetermined stroke. A stopper bolt 90 is inserted into and screwed into the support plate 91 of the tool support base 24 so that its height can be adjusted freely, and the lower end of the bolt 90 is always resting on the plane of the horizontal support plate 82, so that the tool The support stand 24 is held at a predetermined height position relative to the frame 16.

(About the Tool Magazine) A tool magazine 22 holding a large number of tools 20 in a radial manner is supported on the tool support base 24 so as to be rotatably indexable. That is, the tool support stand 24 has
A pivot shaft 92 having an axis inclined diagonally downward at a predetermined angle with respect to a horizontal plane is protruded and fixed, and the tool magazine 22 is rotatably supported on this pivot shaft 92 via a bearing 94. Tool magazine 22
As shown in FIGS. 1 and 7, the tool magazine 22 basically has a disk shape based on a large-diameter spur gear 98, and a plurality of tool grippers 96 are arranged around the outer periphery of the tool magazine 22. and extend radially at equal central angles. The large diameter spur gear 98 is a bearing 9
4 with a bolt 100 and a pinion 106 fixed to a rotating shaft 104 of a motor 102 disposed on a tool support 24 meshes with the spur gear 98.
By rotating the tool magazine 22, a desired tool 20 can be indexed.

As shown in FIG. 1, a hollow cylindrical member 108 is provided with a ball 112 that is elastically pressed by a stored compression spring 110 at an appropriate location on the tool support base 24.
is disposed so that the pivot shaft 92 and its axis are parallel to each other. Furthermore, notches 114 are recessed in the flat part of the spur gear 98 at predetermined intervals in the circumferential direction, and the balls 112 are elastically pressed and seated in the notches 114 to rotate the desired tool 20 in the tool magazine 22. Upon ejection, the tool 20 is click-stopped in place.

As shown in FIGS. 1 and 7, a bifurcated member 116 extending perpendicularly to the pivot shaft 92 is fastened to the tip of the pivot shaft 92 via a bolt 118. A support plate 120 having a predetermined thickness is bridge-fixed to this bifurcated member 116.
A pair of optical sensors 124 each consisting of a light emitting element and a light receiving element are disposed on a pair of mounting plates 122, 122 arranged in parallel on the upper and lower surfaces of the sensor 20, facing each other with their optical axes aligned. A slit disk 126, which is fixed to the bearing 94 and rotates integrally with the tool magazine 22, is interposed between the light emitting element and the light receiving element in a non-contact manner, and blocks the optical axis. Which tool 20 among the plurality of tools 20 held in the main spindle 2 is currently
6 can be instructed by an appropriate electric circuit.

(About the tool gripper) Next, the tool gripper 96 disposed on the outer periphery of the tool magazine 22 will be described. As shown in FIGS. 2 to 4, the tool gripping tool 96 basically comprises a pair of claw members 128, 128 supported by a finger 130 so as to be able to open and close freely. That is, in FIG. 1, the tool magazine 2
A plurality of fingers 130 are fixed by bolts 132 at predetermined central angles and extend in the radial direction in the circumferential direction of the spur gear 98 serving as the base of the second gear. The finger 130 is made of a plate-like member bent at a predetermined angle, and a pair of claw members 128, 128 are pivotally supported at the free end of the finger 130 so as to be openable and closable.

That is, each claw member 128 is bent into a "dog" shape in a plane, and the long arm part 128a and the short arm part 12 are separated from each other by the bent part.
8b. The long arm part 1
Tool gripping surface 129 provided inside the tip of 28a
is formed as a tapered arcuate recess that can be tightly fitted into a chevron-shaped groove 210 provided around the flange 196 of the tool 20. The pair of claw members 128, 128 are pivotally supported on the back surface of the free end of the finger 130 at the bent portion thereof via a pivot pin 134, so that the tool gripping surface 12
9 and 129 can be rotated by a required angle while facing each other. Further, a tension spring 136 is elastically stretched between the long arm portions 128a, 128a, and as shown in FIG.
28 and 128 are always biased in the direction of mutually closing.

Furthermore, the short portion 128b of each claw member 128
The tips of the two are overlapped with each other as shown in FIGS. 2 to 4, and a shaft pin 138 is inserted perpendicularly into the overlapping portion to be freely attached in common. This shaft pin 138 is connected to the finger 130.
It protrudes and extends upward by a required distance through an opening 130a opened in . Therefore, the bell crank mechanism described later moves the shaft pin 138 to the fourth position.
When forcibly biased in the direction of arrow X in the figure, each pawl member 128 rotates outward about the pivot pin 134 while resisting the elasticity of the tension spring 136, causing the grooved flange of the tool 20 to rotate. Release the grip on 196 (FIG. 3). Also, from the state shown in Figure 3,
When the force applied to the shaft pin 138 is released, both claw members 128,
128 close toward each other around each pivot pin 134 to grip the grooved flange 196 of the tool 20 (FIG. 2).

That is, both claw members 12 in the tool gripper 96
8 and 128 are movable between a gripping position where the tool 20 is gripped and a release position where the tool 20 is released, and both claw members 128 and 128 are movable when processing the workpiece.
is moved to the release position. During this machining, the release angle is set in advance so that the spindle head 18 can pass between the two claw members 128, 128. In this case, the bending angle of the finger 130 that supports each tool gripper 96 on the outer periphery of the tool magazine 22 is such that the tool 20 gripped by the rotationally indexed tool gripper 96 can be attached to the tool mounting portion at the tip of the spindle. 5
The axis of the tool 20 is set to a value that allows the axis of the tool 20 to be aligned with the central axis of the spindle 26 when the tool 20 reaches the lower part of the axis 2.

(Regarding the opening/closing mechanism of the tool gripper) As shown in FIG.
4, a bell crank 142 is rotatably supported at the center thereof. The lower end of this bell crank 142 is formed as a bifurcated portion 146, and at a position where the tool gripper 96 comes directly under the main shaft 26 due to rotational indexing of the tool magazine 22, the shaft pin 138 is inserted between the bifurcated portion 146. It is positioned so that it can intervene.

Further, a vertical plate 148 shown in FIGS. 1 and 6 is arranged and fixed to the upper and lower horizontal support plates 82 and 86 attached to the frame 16, and a groove cam 152 consisting of a required bending groove 150 is attached to the vertical plate 148. bolt 1
It is attached via 54. A pin follower 156 is attached to the upper end of the bell crank 142, and this pin follower 156 is connected to the groove cam 1.
52 and can slide along the bending groove 150 thereof. Furthermore, as described above, the tool support base 24 is designed to be able to rise by a predetermined stroke with respect to the frame 16, so the tool support base 24 is raised by the cam operation of the first cam 162 and the first crank 28, which will be described later. When the tool support 24 starts to rise, the bell crank 142, which is pivotally attached to the tool support base 24, also rises integrally. Therefore, the pin follower 156 attached to the upper end of the bell crank 142 slides along the bent groove 150 of the grooved cam 152 fixed to the frame 16 side, and a cam movement is thereby applied to the bell crank 14.
2 will rotate slightly clockwise about the pin 144. That is, the bifurcated portion 146 of the bell crank 142 is connected to the shaft pin 138 of the tool gripper 96.
is driven in the direction of arrow Y in FIG. 4 to close the pair of claw members 128, 128. Conversely, when the bell crank 142 rotates counterclockwise, the bifurcated portion 146 forcibly drives the shaft pin 138 in the direction of arrow X in FIG.
128 will be released.

(Regarding the elevating mechanism of the tool support stand) Next, based on the back movement of the spindle head 18, the tool support stand 2
4 relative to the frame 16 within the automatic exchange area B will be explained. As shown in FIGS. 1, 5, and 6, a first crank 28 having an L-shape is rotatably attached to each inner surface of the opposing side walls 16a, 16b of the frame 16 via a shaft 158. has been done. This first crank 28
A roller 160 is rotatably attached to the end of one short arm portion 167 that constitutes the roller.
Also, as clearly shown in FIG.
The first plate cam 162 formed with the main shaft head 18
It is attached to the side of the frame via bolts 166. Note that this first plate cam 162 is located at a distance below the roller 160 pivotally supported by the first crank 28 when the main shaft head 18 is located at the lower limit of the automatic exchange area B as shown in the figure. It is set like this.

Further, a contactor 170 is fixed to the upper end surface of the other long arm portion 168 of the first crank 28 . This contactor 170 is connected to the top plate 88 of the tool support stand 24, as shown in FIGS. 5 and 6.
Bolts 172 screwed into support plate 91 fixed to
It is always located at a certain distance below the lower end of the . Then, as will be described later, when the servo motor 40 is rotated to raise the main shaft head 18, the inclined cam surfaces 164 of the plate cams 162 attached to both sides of the main shaft head 18, In contact with the roller 160,
The crank 28 is rotated clockwise about the shaft 158. As a result, the contact 170 of the long arm 168 comes into contact with the lower end of the bolt 172, and the tool support 22 is raised along the guide rail 84 by a predetermined stroke. Note that the first
The dimensional ratio of the long arm portion 168 and the short arm portion 167 of the crank 28 and the bending angle of both arms are determined by the ascending distance of the spindle head 18 and the tool support base 2.
It is assumed that the value is set in advance such that the ascending distance of No. 4 matches the ascending distance and the ascending speed thereof is synchronized.

(Regarding the tool holding member release mechanism) Next, when the spindle head 18 and the tool support base 24 are integrally moved back by the first cam 162 and the first crank mechanism 28, the tool mounting portion 52
The second cam and crank mechanism in which the tool clamping member 66 provided therein operates to release the tool 20 will now be described. As shown in FIGS. 1 and 6, a shaft 176 is inserted into the interior of the spindle head 18.
A second crank 30 having an L-shape is mounted so as to be swingable by a predetermined rotation angle. This second
A roller 180 is rotatably attached to the tip of a long arm portion 178 constituting the crank 30, and the tip portion of the short arm portion 182 is branched into the fork portion 81 as shown in FIG. There is. The fork part 81 surrounds the main shaft 26 from the outside, and is always located in a non-contact position slightly above the orthogonal pin 72 inserted into the plug 70 provided at the top of the drawbar 76, and waits for a tool release command. ing.

The motor 56, which rotates the main shaft 26 in response to a machining command, is controlled to always stop at a fixed position when the machining is completed. Therefore, when the motor is stopped, the pin 72 extending perpendicularly from the main shaft 26 also stops at a fixed position directly below the fork portion 81, as shown in FIG.
0, the fork portion 81 can reliably capture the pin 72.

Next, the second crank 3
A second plate cam 188 having a predetermined inclined cam surface 186 is disposed in the path in which the spindle 0 moves upward together with the main shaft head 18, and comes into contact with the second crank 30 to perform a predetermined cam operation. ing.
That is, the second plate cam 188 is
As can be seen from the figure, it is fixed to the vertical casing surface of the rotary encoder 42 via bolts 190, with its inclined cam surface 186 directed vertically downward. Then, when the main shaft head 18 is raised, the roller 180 that is pivotally supported at the tip of the long arm portion 178 of the second crank 30 rides on the inclined cam surface 186 of the plate cam 188. Rotates counterclockwise by a predetermined center angle around . Therefore, the fork part 81 provided at the tip of the short arm part 182 contacts and presses the orthogonal pin 72, and pulls down the drawbar 76 by a predetermined distance, thereby causing the tool holding member 66 to
lower. The ball 68 is then released from the pull stud 64, and the tool 20 is released from being held in the tool mounting portion 52. Note that the second crank 3
A leaf spring 192 is attached to the long arm portion 178 of the spindle head 1, and the free end of the leaf spring 192 is attached to the long arm portion 178 of the spindle head 1.
The crank 30 is always in contact with the upright end surface of a horizontal support plate 194 provided at the top of the crank 30 to apply a clockwise return force to the crank 30.

Note that the first crank 28 and the first plate cam 162
The operation timing of the second crank 30 and the second plate cam 188 are always set to temporally precede the operation timings of the second crank 30 and the second plate cam 188. In other words, as described in the operation explanation section, the first
In the basic position shown in the figure, for example, the spindle head 1
8 rises by 20mm, the first crank 28 moves to the first
It contacts the plate cam 162 and operates the cam to lift the tool support stand 24 by 20 mm, and further lifts the spindle head 18.
By moving to the process of rising by 30 mm, the second
A sequence is preset in which the crank 30 comes into contact with the second plate cam 188 to perform a cam operation, pushes down the draw bar 76, and releases the clamping of the tool clamping member 68 from the pull stud 64 of the tool 20.

Effects of the Embodiment Next, the effects of the machine tool according to the embodiment configured as described above will be explained. FIG. 1 shows that the spindle head 18 completes normal cutting, returns to the upper limit position in the machining operation area A and stops, and the pin 72 is connected to the fork portion 81 of the second crank 30. Indicates a state in which the robot is waiting for the next command after being stopped at a fixed orthogonal position. That is, if the next command is a command to continue cutting, the spindle head 18 moves forward in the machining operation area A to perform machining on the workpiece. If it is a tool exchange command, the spindle head 18 moves upward toward the automatic exchange area B as described later.

In FIG. 1, as a result of the bifurcated portion 146 of the bell crank 142 pressing the shaft pin 138 of the tool gripper 96 in the X direction (FIG. 4), the claw members 128, 128 are released and the tool 20 The grip is released. Further, in FIG. 1, a chevron groove 210 formed in the flange portion 196 of the tool 20 is shown.
is located below the claw member 128 by a distance α, and in this state, even if both claw members 128, 128 are closed, the tool 20 cannot be held in a fixed position. However, in the process of moving from the position shown in FIG. 1 to the position shown in FIG. , the above-mentioned chevron groove 210 is connected to the claw member 12.
The problem of being located a distance α below 8 is solved.

In the state shown in FIG. 1, when a tool change command is issued, the AC servo motor 40 is driven, the ball screw 44 is rotated, and the spindle head 18 is vertically directed toward the automatic change area B via the nut 46. raise. As a result, the spindle head 18 moves to the eighth position.
Entering the first stage of backward motion shown in Figures a and b. That is, as shown in FIG. 8a, the spindle head 18 is independently raised by a distance α, thereby absorbing the distance α between the chevron groove 210 of the tool 20 and the pawl member 128 described above. Further, as the main shaft head 18 rises, the first plate cam 162 moves against the roller 16 of the first crank 28.
0 and rotates the crank 28 clockwise about the shaft 158. For this purpose, a contactor 170 provided on the long arm portion 168 of the crank 28
However, the bolt 172 comes into contact with the lower end of the bolt 172 provided on the support plate 91 of the tool support stand 24. At this time AC
The servo motor 40 is rotated at a slow speed, and the contact 17
The contact noise between the bolt 172 and the bolt 172 is suppressed, and thereafter the motor is driven at a predetermined speed.

Next, as shown in FIG. 8b, the spindle head 18
will rise by 20mm, for example. In this rising process,
The first crank 28 further rotates under the action of the first plate cam 162, and the tool support 24, which is slidably supported on the frame 16, is raised 20 mm integrally with the spindle head 18. As the tool support stand 24 rises, the bell crank 142 pivoted to the tool support stand 24 also rises together, and the pin follower 156 provided at the upper end of the bell crank 142 moves upwardly from the groove cam 152 fixed to the frame 16 side. It slides along the bending groove 150. This provides a cam action, causing the bell crank 142 to rotate slightly clockwise about the pin 144. That is, bell crank 14
The bifurcated portion 146 of the tool gripper 96 is
38 in the direction of arrow Y in FIGS. 2 and 4, the pair of claw members 128, 128 are closed under the elastic action of the tension spring 136, and the tool 2
0 securely grip the flange portion 196.

Further, the spindle head 18 continues to enter the second stage of backward movement shown in FIG. 8c. At this time, the first crank 2
Since the roller 160 of No. 8 is in the process of rolling in contact with the inclined cam surface 164 of the first plate cam 162, the tool support base 24 is raised integrally with the spindle head 18 by, for example, 30 mm. Also, the second
Due to the stepwise return motion, the roller 180 provided on the long arm portion 178 of the second crank 30 comes into contact with the second plate cam 188 located at the upper fixed position, causing the crank 30 to move counterclockwise around the shaft 176. I ended up rotating it. As a result, the fork portion 81 at the tip of the short arm portion comes into contact with the orthogonal pin 72, presses the pin 72 downward, and pulls down the drawbar 76 by a predetermined distance, thereby lowering the tool holding member. Therefore, the ball 68 is attached to the pull stud 64 of the tool 20.
The gripping of the tool 20 in the tool mounting portion 52 at the tip of the main shaft 26 is also released. At this time, since the tool 20 is already gripped by the tool gripper 96 (as described above), the tool 20 will not fall off due to its own weight. Note that the bell crank 142 attached to the tool support stand 24 rises with respect to the grooved cam 152 fixed to the frame 16 side, but the pin 14
4 has already passed through the inclined groove of the bending groove 150 and the main shaft 2
6, the bell crank 142 does not cam in this area.

Next, the spindle head 18 enters the third stage of backward movement, as shown in FIG. 8d, and is raised, for example, by 70 mm.
At this time, the roller 160 of the first crank 28 is
Since it rests on the flat surface of the plate cam 162, the cam does not operate, so the tool support 24 does not rise, and only the spindle head 18 rises independently. Further, the roller 180 of the second crank 30 is also connected to the second plate cam 1.
Since it rides on the flat surface of 88 and does not operate the cam,
The draw bar 76 also remains pressed down, and the pull stud 64 remains unclamped. Moreover, as described above, since the tool 20 is already held in place by the tool gripper 96, the tool 20 is held in place by the independent lifting of the spindle head 18.
0 arbor 62 is attached to the tool mounting portion 5 at the tip of the main spindle 26
Extracted from 2. The spindle head 18 then stops at a position above the top of the pull stud 64 of the tool 20 held by the tool gripper 96.

Next, the motor 102 of the tool magazine 22 is driven to rotationally index the tool 20, carry away the tool 20 extracted from the tool mounting section 52, and transfer the newly selected desired tool 20. It is brought to a position below the tool mounting portion 52 and stopped with the axes aligned. Automatic tool exchange is then achieved by reversing the operations shown in FIGS. 8a-d. That is, the spindle head 18 is 70
When the arbor 62 of the tool 20 is lowered by mm, the arbor 62 of the tool 20 is attached to the tool mounting portion 52, and by further lowering by 30 mm, the pressure of the second crank 30 on the drawbar 76 is released, and under the elastic action of a group of disc springs 78, A tool clamping member 66 clamps the pull stud 64 of the tool 20. By continuing to lower the spindle head 18 and tool support 24 by 20 mm,
The bell crank 142 operates in reverse, and the tool gripper 9
6 in the X direction in FIG. 4, the claw members 128, 128 are released, and the grip on the tool 20 is released.

In this way, the claw members 128, 128 are attached to the tool 20.
When a machining operation command is issued in the state shown in FIG.
The spindle head 18 equipped with the newly replaced tool 20 is vertically lowered toward the machining operation area A, as shown in FIG. At this time, both claw members 12
8 and 128 are wide open as described above, the spindle head 18 is able to hold these claw members 128 and 12.
8 and can immediately proceed to the cutting process.

Effects of the Invention As explained above, the machine tool according to the present invention is configured such that a pressing body that functions to push down a drawbar slidably disposed on a hollow spindle is disposed on the side of the spindle. There is. Therefore, it is possible to directly connect the output shaft of the main shaft driving means for rotationally driving the hollow main shaft to one end in the axial direction of the hollow main shaft, and to efficiently transmit power to the hollow main shaft by the main shaft driving means. This makes it possible to improve the machining accuracy using the hollow spindle. In addition, in this case, when controlling the stop of the spindle drive means, the hollow spindle can be accurately stopped at a fixed position, so that the pressing body and the pin arranged on the side of the spindle are always in corresponding positions. Therefore, the drawbar can be pressed down reliably. Furthermore, as a result of arranging the pressing body on the side of the hollow main shaft, the height dimension of the main shaft head can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the internal structure of a machine tool according to a preferred embodiment of the present invention, and FIG. 2 is a perspective view showing a schematic structure of a tool grip used in the machine tool of the embodiment. Fig. 3 shows a state in which a pair of claw members are closed to grip the flange portion of the tool, and Fig. 3 shows a state in which the pair of claw members in the tool gripper are released to release the grip on the flange portion of the tool. The state is shown, and FIG. 4 is a schematic plan view of the tool grip,
Fig. 5 is a partially cutaway side view of the machine tool shown in Fig. 1, Fig. 6 is a partially cutaway plan view of the machine tool shown in Fig. 1, and Fig. 7 is a partially cutaway side view of the machine tool shown in Fig. 1. FIGS. 8a to 8d are explanatory diagrams showing the operating order of the machine tool according to the embodiment. FIG. 9 is a partial cutaway schematic diagram, and FIG.
FIG. 10 is an explanatory diagram illustrating a case in which the machining operation continues, and shows a state in which the spindle head passes between both released claw members of the tool grip; FIG. FIG. 2 is a schematic explanatory diagram showing the overall arrangement of main constituent members. 16...Frame, 18...Spindle head, 20
... Tool, 26 ... Main shaft, 30 ... Second crank, 40 ... AC servo motor, 52 ... Tool attachment part, 56 ... Drive motor, 60 ... Output shaft,
64...Pull stud, 66...Tool holding member,
72...pin, 74...slot, 76...drawbar, 78...disc spring, 81...fork part,
188...Second plate cam.

Claims (1)

[Claims] 1. A hollow main shaft 26 having a tool mounting portion 52 at one end.
a spindle head 18 rotatably supported by the frame 16 along the axis of the hollow main shaft 26; a feed motor 40 for moving the spindle head 18 along the axis; A main shaft drive having an output shaft 60 provided on the head 18 and extending on the same axis as the axis of the hollow main shaft 26, and connecting the output shaft 60 to the hollow main shaft 26 in order to rotationally drive the hollow main shaft 26. The pull stud of the tool 20 mounted on the tool mounting portion 52 of the hollow main shaft 26 is always operated by means 56, 58 and an appropriate biasing means 78 which is slidably inserted into the center hole of the hollow main shaft 26. 64; a drawbar 76 having one end connected to the tool holding member 66 and the other end housed in the center hole of the hollow main shaft 26; and a slot 74 formed in the hollow main shaft 26 so as to extend along the axis; and a slot 74 fixed perpendicularly to the other end of the drawbar 76, with a free end extending outside the hollow main shaft 26 through the slot 74. a pin 72 that extends in the direction; a pressing body 30 that is movably supported by the spindle head 18 and has an engaging portion 81 that can be engaged with the pin 72; and between the pressing body 30 and the frame 16. The feed motor 40 moves the spindle head 18
is moved to the tool exchange position, the pressing body 30 pushes the pin 72 toward the urging means 78.
A machine tool characterized by comprising an interlocking means 188 for pushing against the force.