JPH0386408A - Machine tool - Google Patents

Abstract

PURPOSE:To effectively transmit power through a driving motor to a hollow spindle by providing a pressing body functioning to push down a draw bar slidably provided in a hollow spindle on the side of the spindle. CONSTITUTION:A draw bar 76, the one end of which is coupled with a tool holding member 66 and the other end of which is received in a central hole of a hollow spindle 26, is provided, and the spindle 26 is formed with a slot 74 which is opposite to the other end of the draw bar 76 and extends along its axis. The free end of a pin 72 fixed crossingly at right angles to the other end of the draw bar 76 is stretched out of the spindle 26 through the slot 74, and a pressing body 30 movably supported on a spindle head 18 is provided with an engaging part which can engage with the pin 72. An interlocking means 188, which interlocks with the spindle head 18 moved by a feeding motor 40 to a tool exchange position and makes the pressing body 30 push the pin 72 against an energizing means 78, is provided between the pressing body 30 and a frame 16.

Description

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

Conventional technology Machine tools such as machining centers (MCs) that can perform various types of processing such as thread cutting and hole drilling on workpieces are equipped with tools such as taps and drills that are securely attached to the tool attachment part of the spindle. Means are provided for removal. For example, in a machine tool disclosed in Japanese Utility Model Application Publication No. 55-151435, a drawbar with a tool mounting portion formed at one end is pushed into the main spindle, and the tool is firmly attached to the tool mounting portion of the drawbar. A configuration in which the device is attached to the camera is known. Further, a mechanism for forcibly pushing down the drawbar in the axial direction is disposed on the upper part of the main shaft, and the tool is removed from the tool mounting portion by pushing down the drawbar by the mechanism.

Problems to be Solved by the Invention In the machine tool configured as described above, a mechanism for pushing down the drawbar is provided above the main shaft, so the main shaft is directly connected to a drive source such as a motor or a speed reducer that drives the main shaft. I can't. For this reason, a pulley is placed at an appropriate position on the main shaft,
The main shaft is configured to be rotationally driven by being connected to a drive motor via a belt wrapped around the pulley. In this case, in the power transmission using the pulley and the belt, r-slip J inevitably occurs, which causes a problem in that the rotational speed of the main shaft changes and machining accuracy decreases.

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, in the belt drive system, there is a risk of bending deformation of the main shaft. Therefore, it is necessary to strengthen and reinforce the support structure for the main shaft, but this also has the disadvantage of complicating the structure and increasing costs.

OBJECTS OF THE INVENTION The present invention has been proposed in view of the above-mentioned disadvantages inherent in the machine tools described above, in order to suitably solve the problems. 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. shall be.

Means for Solving the Problems In order to overcome the above problems and achieve the intended purpose, the present invention rotatably supports a hollow main shaft having a tool mounting portion at one end, and supports the hollow main shaft along the N line of the hollow main shaft. a spindle head movably supported by the frame; and a feed motor that moves the spindle head along the axis.

a tool holding member that is slidably inserted into the center hole of the hollow spindle and, by the action of an appropriate biasing means, always holds a pull stud of a tool attached to the tool mounting portion of the hollow spindle; a drawbar connected to the tool holding member and having the other end housed in the center hole of the hollow main shaft;
a slot formed in the hollow main shaft so as to face the other end and extend along the axis; and a slot fixed perpendicularly to the other end of the drawbar, the free end of which is connected to the hollow main shaft through the slot. a pin extending outward from the spindle; a pressing body movably supported by the spindle head and having an engaging portion that can be engaged with the pin; and a pressing body provided between the pressing body and the frame, the The present invention is characterized by comprising an interlocking means for causing the pressing member to push the pin against the urging means in conjunction with movement of the spindle head to the tool exchange position by the motor.

Embodiment Next, a preferred embodiment of a machine tool according to the present invention will be described below with reference to the accompanying drawings. FIG. 10 shows the overall schematic configuration of the machine tool 10 according to the embodiment.
, 111 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. This tool support stand 2
4, a disk-shaped tool magazine 22 in which a plurality of tool grippers 96 are arranged radially is rotatably supported. 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.

(About the spindle head and its elevating system) As shown in Fig. 10, it is arranged upright on the base 12: A hollow box-shaped frame 6 is horizontally arranged and fixed on the front of the I-ram 14, and the spindle 26 can be freely rotated. A spindle head 18 supported by the main shaft head 18 is disposed within the frame 16 so as to be movable up and down. That is, as shown in FIG. 5 and FIG.
A guide rail 36 is vertically fixed to each longitudinal end surface of the guide rail 36 via a screw 34. A left and right pair of sliding tops 38.3 are arranged at the rear of the spindle head 18 in pairs, upper and lower.
8 and correspondingly fit into the guide rails 36, 36, the spindle head 18 can be raised and lowered perpendicularly to the frame 16.

Further, a support plate 39 is fixed horizontally between the tops of the pair of long column members 3'2, 32, and the rotary encoder 4
An AC servo motor 4o having a built-in AC servo motor 2 is disposed upright on the support plate 39. The rotation 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. It extends to 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. And said A
By rotating the C servo motor 4o, the ball screw 44 rotates in a desired direction, giving linear motion to the nut 46.

The spindle head 18 is freely driven up and down in the vertical direction by a predetermined stroke.

As shown in FIG. 5, the areas where the spindle head 18 moves up and down are: (1) a machining operation area A where the spindle head 18 repeatedly moves up and down towards the workpiece to perform the required cutting process; and (2) above this area. The tool 20 relative to the spindle 26 is located at a level.
It is roughly divided into an automatic exchange area B where a series of attachment/detachment exchange operations are performed. Then, the spindle head 18 moves through the automatic exchange area B.
In the process of backward movement and upward movement, three inflection points appear that cause a series of tool exchange operations to be performed (described later). Incidentally, the spindle head 18 shown in FIGS. 1, 5, and 10 is
The machine has finished machining the workpiece and has reached the upper limit of the machining operation area A (the lower limit of the automatic exchange area B), and is in a state of waiting for either the next machining command or tool exchange command.

(About the tool mounting structure of the spindle) The main spindle head 18 is as shown in FIG.

A hollow cylindrical main shaft 26 is rotatably supported vertically via upper and lower bearings 50, 50. Also, the spindle head 1
A motor 56 with a speed reducer 58 is disposed upright on top of the motor 8 , and its output shaft 60 is connected to the upper end of the main motor 826 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 gFJO portion is formed at the lower end of the main shaft 26, and the tool 20 provided with the arbor 62 can be removably mounted thereon. A pull stud 64 is provided at the rear end of the tool 20, and the tool 20 is fixed to the main shaft 26 by holding the pull stud 64 with a tool holding member 66 that is freely inserted into the hollow main shaft 26. will be done. 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 6
4 clamps and releases can be performed.

As shown in FIG. 1, a plug 70 is inserted into the hollow portion of the main shaft 26 so as to be vertically slidable, and a drawbar 76 whose upper end is inserted and fixed into the vertical hole of the plug 70 is inserted along the central axis of the main shaft 20. The lower end thereof is connected to the top of the tool holding member 66. The position of the plug 70 in the main shaft 26 has an oval slot 74.7.
4 are oppositely bored (FIG. 1), and both ends of a pin 72 inserted perpendicularly into the plug 70 extend horizontally to the outside of the main shaft 26 through the pair of slots 74 and 74. (Figure 6). As shown in FIG. 1, when the tool 20 is mounted on the tool mounting portion 52, a group of washers 80 are formed between the step formed below the hollow part of the spindle and the washer 80 provided at the lower end of the plug 70. Disc springs 78 are elastically compressed and inserted, and a draw bar 76 is inserted through and extends through the center of a large number of disc springs 78. The elasticity of the disk spring 78 always presses the plug 70 upward and holds it in place, and elastically pulls up the tool holding member 66 to ensure that the pull stud 64 is held.

Note that above the orthogonal pin 72 extending outward from the main shaft,
As shown in FIGS. 1 and 6, a bifurcated fork portion 81 faces closely to the tip of a second crank 30, which will be described later, and the operation of the crank 30 presses and biases the pin 72 to open the drawbar. 76 is lowered.

That is, the second cam 188 and the second crank 3, which will be described later.
When the orthogonal pin 72 is pressed downward by the cam operation of 0, the draw bar 76 descends in the axial direction, lowers the tool holding member 66, and releases the pull stud 64 from being suppressed by the ball 68. 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, a tool support stand 24 that rotatably supports the tool magazine 22 is supported so as to be movable in the axial direction of the main shaft 26. 1 and 6, opposite side walls 16a, 16 of the frame 16
Support plates 82, 82 are horizontally attached to b, and round bar-shaped guide rails 84 are slidably inserted into vertical through holes bored at appropriate positions in each horizontal support plate 82. Further, as shown in FIG. 1, a pair of left and right horizontal support plates 86 extend from below the frame 16, and the guide rails 84 are slidably inserted into vertical through holes formed in the horizontal support plates 86. has been done. The upper and lower ends of the guide rails 84 (there are two as shown in FIG. 6) are connected to the tool support stand 2.
They are fixed to a support plate 91 provided on a horizontal top plate 88 bridged over the top of 4 and a support plate 89 provided on the bottom, 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, 86, and by the cam operations of the first cam 162 and the first crank 28, which will be described later. It is driven up and down by a predetermined stroke. A stopper bolt 90 is inserted and screwed into the support plate 91 of the tool support stand 24 so that the height can be adjusted freely, and the lower end of the bolt 90 is always attached to the horizontal support plate 8.
By resting on the plane 2, the tool support 24 is held at a predetermined height position with respect 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, a pivot 92 having an axis inclined diagonally downward at a predetermined angle with respect to the horizontal plane is protruded and fixed to the tool support base 24, and the tool magazine 22 is rotatably supported on this pivot 92 via a bearing 94. ing. 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 provided on the outer periphery of the tool magazine 22. are arranged and extend radially at equicentric angles. The large diameter spur gear 98 is fixed to the bearing 94 with bolt gear OO,
Rotating shaft 104 of motor 102 arranged on tool support stand 24
A pinion 106 fixedly engaged with the spur gear 98 rotates the tool magazine 22, thereby making it possible to index a desired tool 20.

As shown in FIG. 1, balls 11 are elastically pressed into appropriate positions on the tool support stand 24 by a stored compression spring 110.
A hollow cylindrical member 108 having a diameter of 2 is disposed with its axis parallel to the pivot shaft 92. 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 of a predetermined thickness is bridge-fixed to this bifurcated member 116, and a pair of optical sensors 124 each consisting of a light emitting element and a light receiving element are mounted on a pair of mounting plates 122, 122 arranged parallel to the upper and lower surfaces of the support plate 120. are arranged facing each other with their optical axes aligned. A slit disk 126 that is arranged and 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 2 among the plurality of tools 20 held in
Whether or not 0 is currently held on the main shaft 26 can be indicated 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, this tool gripping tool 96 includes a pair of pawl members 28 and 128 supported on a finger 130 so as to be able to open and close freely.
It basically consists of That is, in FIG. 1, a plurality of fingers 130 are fixed by bolts 132 at a predetermined center angle and extend in the radial direction in the circumferential direction of a spur gear 98 that serves as the base of the tool magazine 22. This finger 1
30 is a plate-shaped member bent at a required angle, and a pair of claw members 128, 128 are provided at the free end of the finger 130.
is pivoted so that it can be opened and closed freely.

That is, each claw member 128 is bent in a "<" shape in a plane, and the long arm portion 1 is formed with the bent portion as a boundary.
28a and a short arm portion 128b. A tool gripping surface 129 provided inside the tip of the long arm portion 128a is formed as a tapered arcuate recess that can tightly fit into a chevron-shaped groove 210 provided around the flange 196 of the tool 20. These pair of claw members 128, 128 are connected to the finger 1 at the bent portion thereof.
is pivotally supported on the back surface of the free end of 30 via a pivot pin 134,
This allows the tool gripping surfaces 129 to be rotated by a required angle while facing each other. In addition, a tension spring 13 is inserted between the long arm portions 128a and 128a on one side.
6 is elastically tensioned, and as shown in the second @, both claw members 128, 128 are normally urged in a direction to close each other.

Furthermore, the tips of the short portions 128b of each claw member 128 are overlapped with each other as shown in FIGS. It's a dress.

The shaft pin 138 extends upward by a required distance through an opening 130a formed in the finger 130. Therefore, by the bell crank mechanism described later,
When the shaft pin 138 is forcibly biased in the direction of the arrow X in FIG. , when the grip on the grooved flange 196 of the tool 20 is released (FIG. 3), and when the biasing force on the shaft pin 138 is released from the state shown in FIG. The members 128, 128 are.

They are closed in a direction 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 128.12 in the tool gripper 96
8 is movable between a gripping position for gripping the tool 20 and a release position for releasing the tool 20, and both claw members 128, 128 are moved to the release position when processing a workpiece. During this machining, the spindle head 8 is moved to both claw members 12.
The release angle is preset to a value that can pass between 8 and 128. In this case, the bending angle of the fingers 130 that support each tool holder 96 on the outer periphery of the tool magazine 22 is such that the tool 2 held by the tool holder 96 is indexed one rotation.
0 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 below the tool mounting portion 52 at the tip of the spindle.

(Regarding the opening/closing mechanism of the tool gripper) As shown in FIG. 1, a bell crank 142 is attached via a pin 144 to a clevis 140 integrally formed on the support plate 89 of the tool support stand 24, and is rotatable at the center thereof. is supported by. 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.

Also, upper and lower horizontal support plates 82.8 attached to the frame 16
6, a vertical plate 148 shown in FIGS. 1 and 6 is arranged and fixed, and a groove cam 152 having a required bent groove 150 is attached to the vertical plate 148 via bolts 154. A pin follower 156 is attached to the upper end of the bell crank 142, and the pin follower 156 is inserted into the groove cam 152 and can slide along the bent groove 150 thereof. Moreover, as mentioned above, the tool support stand 2
4 can be raised by a predetermined stroke with respect to the frame 16, so by the cam operation of the first cam 162 and the first crank 28, which will be described later, the tool support base 2
4 starts to rise, the bell crank 142, which is pivoted to the tool support stand 24, also rises together. Therefore, the bin follower 156 attached to the upper end of the bell crank 142 is attached to the structural cam 152 fixed to the frame 16 side.
The bell crank 142 slides along the bent groove 150 of the bell crank 142, thereby applying a cam action, causing the bell crank 142 to rotate slightly clockwise about the pin 144. That is, the bifurcated portion 146 of the bell crank 142 is connected to the tool grip 96.
drive the shaft pin 138 in the direction of arrow Y in FIG.
The pair of claw members 128, 128 are closed. And vice versa,
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. 4, thereby releasing the pair of pawl members 128, 128.

(Regarding the Lifting Mechanism for the Tool Support Stand) Next, a mechanism for raising the tool support stand 24 relative to the frame 16 within the automatic exchange area B based on the return movement of the spindle head 18 will be described. As shown in FIG. 1, FIG. 5, and FIG.
58, and are rotatably connected to each other. This first
A roller 160 is rotatably attached to the end of one short arm portion 167 that constitutes the crank 28 . Further, as clearly shown in FIG. 5, a first plate cam 162 having an inclined cam surface 164 is attached to the side surface of the spindle head 18 via a bolt 166. The 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 8 is located at the lower limit of the automatic exchange area B as shown in the figure. It is set like this.

In addition, the other long arm portion 16 of the first crank 28
8 has a contact 170 fixed to its upper end surface.

This contactor 170, as shown in FIGS. 5 and 6,
The bolt 172 is always located at a certain distance and below the lower end of the bolt 172 screwed into the support plate 91 fixed to the top plate 88 of the tool support stand 24 . And as explained later,
When the servo motor 40 is rotated to raise the spindle head 8, the inclined cam surfaces 164 of the plate cams 162 attached to both sides of the spindle head 18 come into contact with the rollers 160 of the first crank 28. , the crank 28 is rotated clockwise about the shaft 158. As a result, the contact ↓70 of the long arm portion 168 is connected to the bolt 17.
2, and the tool support base 22 is raised along the guide rail 84 by a predetermined stroke. The dimensional ratio of the long arm section 168 and the short arm section 167 of the first crank 28 and the bending angle of both arms are such that the ascending distance of the spindle head 18 and the ascending distance of the tool support base 24 match, and the ascending speed thereof It is assumed that the values are set in advance so that they are synchronized.

(Regarding the tool clamping member release mechanism) Next, the first cam 162 and the first crank mechanism 28
The second cam and crank mechanism that operates to release the tool 20 by the tool holding member 66 provided in the tool mounting portion 52 when the spindle head 8 and the tool support stand 24 are integrally moved back will be explained. . No. 7 engineering drawing and No. 6
As shown in the figure, a second crank 30 having an L-shape is mounted inside the spindle head 18 via a shaft 176 so as to be swingable by a predetermined rotation angle. A roller 1 is attached to the tip of the long arm portion 178 that constitutes the second crank 30.
80 is rotatably pivoted, and the short arm portion 18
As shown in FIG.
Branches are formed as follows.

The fork part 8 surrounds the main shaft 26 from the outside, and is always positioned in a non-contact manner slightly above the orthogonal pin 72 inserted into the plug 70 provided at the top of the drawbar 76 to issue a tool release command. I'm waiting.

In addition, the motor 5 rotates the main shaft 26 in response to a machining command.
No. 6 is controlled to always stop at a fixed position when the machining is completed. Therefore, when the motor stops, 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.
When the crank 30 is operated, the fork part 8 is securely connected to the pin 7.
2 can be captured.

Next, a second temporary cam 188 having a predetermined inclined cam surface 186 is disposed on a path in which the second crank 30 moves upward together with the spindle head 18 in the automatic exchange area B. A predetermined cam operation is performed by making contact with the cam.

That is, as can be seen from the construction drawings and FIG. 6, the second plate cam 188 is fixed to the vertical casing surface of the rotary encoder 42 via bolts 190, and has its inclined cam surface 86 directed vertically downward. ing. Then, when the main shaft head 18 is raised, the roller 180 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 . For this purpose, the fork portion 8 provided at the tip of the short arm portion 182 contacts and presses the orthogonal pin 72, and the draw bar 76 is pulled down by a predetermined distance, thereby lowering the tool holding member 66. and ball 6
8 is released from the pull stud 64, and the tool mounting portion 5
2. Release the grip of the tool 20 in step 2. A leaf spring 192 is attached to the long arm 178 of the second crank 30, and the free end of the leaf spring 192 is in constant contact with the upright end surface of a horizontal support plate 194 provided at the top of the spindle head 8.
A clockwise return force is applied to the crank 30.

Note that the operation timing of the first crank 28 and the first plate cam 162 is the same as that of the second crank 30 and the second temporary cam 1.
It is assumed that the timing is always set to temporally precede the operation timing of 88. That is, as described in the operation description section, in the basic position shown in FIG. 1, while the spindle head 18 is raised by 20 mm, for example, the first crank 28 contacts the first work plate cam 162 and performs cam operation to support the tool. By lifting the stand 24 by 20 mm and proceeding to the process of further raising the spindle head 8 by 30 m+++,
The second crank 30 comes into contact with the second plate cam 188 and performs cam operation, pushing down the drawbar 76 and pushing down the tool 20.
The sequence is set in advance to release the clamping of the tool clamping member 66 from the pull stud 64.

Operation of the embodiment Next, the operation of the machine tool according to the embodiment configured as described above will be explained. FIG. 1 shows that the spindle head 8 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 first 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. Further, if it is a tool exchange command, the spindle head 18 moves upward toward the automatic exchange area B as described later.

In addition, in FIG. 1, the bifurcated portion 14 of the bell crank 142
6 presses the shaft pin 138 of the tool gripper 96 in the X direction (FIG. 4), and as a result, the claw members 128, 128 are released and the grip on the tool 20 is released. Further, in FIG. 1, the chevron groove 210 formed in the flange portion 196 of the tool 20 is located below the claw member 128 by a distance α, and in this state, even if both the claw members 128, 128 are closed, The tool 20 cannot be held in place. However, due to the rise of the spindle head 18, the
In the process of shifting to the position shown in FIG.
The problem that 10 is located below the claw member 128 by a distance α is solved.

In the state shown in FIG. 1, when a tool change command is issued, the AC servo motor 40 is driven and the ball screw 4 is
4 rotates to vertically raise the spindle head 18 towards the automatic exchange area B via the nut 46. As a result, the spindle head 18 enters the first stage of backward movement shown in the eighth section (a) and (b). That is, as shown in FIG. 8(a), the spindle head 18 rises by itself by a distance α, thereby absorbing the distance α between the chevron-shaped groove 210 of the tool 20 and the pawl member 128 described above. Furthermore, as the main shaft head 18 rises, the first plate cam 162 comes into contact with the roller 160 of the first crank 28, causing the crank 28 to rotate clockwise about @158. Therefore, the contact 170 provided on the long arm portion 168 of the crank 28 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, the AC servo motor 40 is rotated at a very low speed to suppress the contact noise between the contact 170 and the bolt 172, and thereafter is driven at a predetermined speed.

Next, as shown in FIG. 8(b), the spindle head 18 is, for example, 201III! Rise. During this ascending process, the first crank 28 further rotates under the action of the first work plate cam 162, and the tool support 24, which is slidably supported on the frame 16, is integrally moved by 20fflf with the spindle head 18.
Increase fi. As the tool support stand 24 rises, the bell crank 142 pivotally attached to the tool support stand 24 also rises integrally, and the pin follower 156 provided at the upper end of the bell crank 142 also rises.
slides along the bent groove 150 of the grooved cam 152 fixed to the frame 16 side. This provides a cam action, causing the bell crank 142 to rotate slightly clockwise about the pin 144. That is, bell crank 142
The bifurcated portion 146 holds the shaft pin 138 of the tool gripper 96,
The tool 20 is driven in the direction of the arrow Y in FIGS. 2 and 4, and the pair of claw members 128 and 128 are closed under the elastic action of the tension spring 136, thereby reliably gripping the flange portion 196 of the tool 20.

Furthermore, the main spindle head 18 continues to move to the second position shown in FIG. 8(Q).
Entering a step-by-step return movement. At this time, the roller 160 of the first crank 28 is in the process of rolling in contact with the inclined cam surface 164 of the first plate cam 162, so the tool support 24 is integrally formed with the spindle head 18, for example, by 30 mm. Rise. Further, due to the second stage of the return movement of the main shaft head 18, 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, and the crank 30 is moved toward the shaft 176. Rotate counterclockwise around the center. As a result, the fork portion 81 at the tip of the short arm portion contacts the orthogonal pin 72, presses the pin 72 downward, and pulls down the drawer 76 by a predetermined distance, thereby lowering the tool holding member.

Therefore, the ball 68 is released from the pull stud 64 of the tool 20, and the tool 20 is also released from being held in the tool mounting portion 52 at the tip of the main shaft 26. At this time, since the tool 20 is already gripped by the tool gripper 96 (as described above), the tool 20 will not fall downward due to its own weight. The bell crank 142 attached to the tool support stand 24 rises, but the pin 144 has already passed through the inclined groove of the bent groove 150 and is attached to the main #12.
6, the bell crank 142 does not operate as a cam in this area.

Next, the spindle head 18 enters the third stage of backward movement, as shown in FIG. 8(d), and rises by, for example, 70 mm. At this time, the roller 160 of the first crank 28 is
Since the tool rests on the flat surface of the tool, 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 rides on the flat surface of the second plate cam 188 and does not operate, so the drawbar 76 also remains pushed down and the pull stud 64 is still held in place. It remains unlocked. Furthermore, as described above, since the tool 20 is already held in a fixed position by the tool gripper 96, the arbor 62 of the tool 20 is extracted from the tool mounting portion 52 at the tip of the main spindle 26 by the independent rise of the spindle head 18. 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. 8(a) to 8(d). That is, when the spindle head 18 descends by 70 mm, the tool 2° arbor 62 is attached to the tool mounting portion 52, and by descending further by 30 mm, the pressure of the second crank 30 on the drawbar 76 is released, and the plates of the − group are removed. Under the elastic action of the spring 78, the tool clamping member 66 clamps the pull stand 64 of the tool 20. As the spindle head 18 and tool support stand 24 continue to descend by 20 mm, the bell crank 142 operates in reverse to press the foot pin 138 of the tool gripper 96 in the X direction in FIG. Open to release the grip on the tool 20.

In this way, when a machining operation command is issued in the state shown in FIG. 8(a) in which the claw members 128, 128 have released their grip on the tool 20, the ball screw 44 is rotated by the drive of the AC servo motor 40. Newly replaced tool 2
The spindle head 18 with the 0 attached thereto is vertically lowered toward the machining operation area A, as shown in FIG. At this time, since both pawl members 128.degree. ↓It is possible to pass through between 28 and immediately proceed to cutting.

As described in detail, the machine tool according to the present invention is configured such that a pressing body is disposed on the side of the main spindle and functions to push down a drawbar that is slidably disposed on the hollow main spindle. There is. Therefore, it becomes possible to directly connect the drive motor to one end in the axial direction of the hollow spindle, and the drive motor can efficiently transmit power to the hollow spindle, thereby improving the machining accuracy of the hollow spindle. In addition, in this case, when controlling the drive motor to stop, the hollow main shaft can be accurately stopped at a fixed position, so that the pressing body and the pin arranged on the side of the main shaft 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 spindle, the height dimension of the spindle head can be shortened.

[Brief explanation of drawings]

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. There it is,
FIG. 3 shows a state in which a pair of claw members are opened 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; FIG. 4 is a schematic plan view of the tool grip;
Fig. S 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.
8(a) to 8(d) are explanatory diagrams showing the operation sequence of the machine tool according to the embodiment, and FIG. It is an explanatory view showing a case where a machining command is received from the state shown in a) and the machining operation continues, showing a state in which the spindle head is passing between the released claw members of the tool grip, FIG. 10 is a schematic explanatory diagram showing the overall arrangement of the main constituent members of the machine tool according to the embodiment. Machining 6...Frame 20...Tool 30...Second crank 40...AC servo motor 56...Drive motor 64...Pull stud 72...Pin 18...Spindle head 26 ...Main shaft 2...Tool mounting part O...Output shaft 6...Tool holding member 4...Slot 76...Drawer 78...Disc spring 81...Fork part 188... 2nd plate cam main shaft head tool main shaft 2nd crank tool mounting part driving motor tool clamping member bin fork part... 2nd plate cam FIG, 10

Claims (1)

[Claims] A hollow main shaft (26) having a tool mounting portion (52) at one end is rotatably supported, and is movably supported by a frame (16) along the axis of the hollow main shaft (26). a spindle head (18), a feed motor (40) for moving the spindle head (18) along the axis, and a feed motor (40) that is slidably inserted into the center hole of the hollow spindle (26) and is fitted with appropriate attachments. Due to the action of the force means (78), the tool (2) attached to the tool attachment portion (52) of the hollow main shaft (26) is always
Tool holding member (0) that holds the pull stud (64)
66), and a drawbar (66) whose one end is connected to the tool holding member (66) and whose other end is accommodated in the center hole of the hollow main shaft (26).
76); a slot (74) formed in the hollow main shaft (26) so as to face the other end of the drawbar (76) and extend along the axis; and the other end of the drawbar (76). fixed orthogonally to the side,
The free end is connected to the hollow main shaft (
a pressing body (30) having a pin (72) extending outwardly from the spindle head (26) and an engaging portion (81) movably supported by the spindle head (18) and capable of engaging with the pin (72); ), which is provided between the pressing body (30) and the frame (16), and is driven by the feed motor (40) to the spindle head (18).
) is moved to the tool exchange position, the pressing body (30) moves the pin (72) to the urging means (78).
) A machine tool characterized by comprising an interlocking means (188) for pushing the machine tool forward against the force.