JPH06218607A - Main spindle device - Google Patents

Abstract

PURPOSE:To detect surely and speedy whether a tool is installed in a tapered hole of a main spindle or not before ATC action. CONSTITUTION:In a tool clamping mechanism, a draw bar 6 is pulled up by a coned disc spring 5, a pull stud 8 is held by closing collet 7, and a tool 3 is pressed into a tapered hole 10. Then, the draw bar 6 is pushed down by the piston rod 12 of a cylinder 11 and the tool 3 is released by opening the collet 7. When the tool 3 is not installed, the tool 3 is pushed forward at the stroke end of a piston rod 12 from a tapered hole 10 by a prescribed beating allowance by the draw bar 6. Then a highly accurate limit switch 20 is engaged with a dog 16 on the piston rod 12 so as to generate a tool drawing signal. When the tool 3 is installed, the piston rod 12 stops just before the stroke end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle device of a machining center in which tools are automatically replaced by an ATC device.

[0002]

2. Description of the Related Art Generally, in a machining center,
As shown in FIG. 5, the spindle head 1 moves in the X-axis and Z-axis directions to attach and detach the tool 3 on the ATC magazine 2 to the spindle 4. Apart from this, there is also known a system in which an exchange arm moves between a spindle head and an ATC magazine to detach a tool from the spindle.

In order to enable such ATC operation,
As shown in FIG. 6, a conventional machining center is equipped with a spindle device having a tool tightening mechanism and a tool loosening mechanism. The tool tightening mechanism uses a disc spring 5 to draw a drawbar 6
, The collet 7 is closed and the pull stud 8 is gripped, the taper shank 9 is press-fitted into the taper hole 10, and the tool loosening mechanism pushes down the draw bar 6 with the piston rod 12 of the cylinder 11 to open the collet 7 and pull pull stud. Release 8. And when the collet 7 opens,
The dog 13 on the piston rod 12 turns on the limit switch 14, and in response to the tool loosening signal from the limit switch 14, the ATC device starts the replacement operation.

[0004]

By the way, in the spindle device of this type, the tool 3 sometimes bites into the tapered hole 10 and cannot be pulled out. This is likely to occur after the tool 3 has been used for a long time, and also due to thermal expansion of the tool 3 and fretting corrosion of the tapered portion. When the ATC operation is started in this biting state, the gripper 15 and the replacement arm of the ATC magazine 2 as shown in FIG. 5 usually do not have enough force to pull out the bited tool.
There is a risk of damaging the equipment on the ATC device side.

However, according to the conventional spindle device, when the collet 7 is opened, the limit switch 14 generates a tool loosening signal, so that it is not possible to confirm whether or not the tool 3 is biting on the taper 10. However, there is a possibility that the ATC device may operate in the stuck state.

Further, conventionally, there is also known a spindle device having means for detecting bite of a tool based on the operation delay of the ATC device. However, according to this, in the case of the machining center of the type shown in FIG. 5, since there is no operation delay in the spindle head 1, the spindle head 1 having a strong cutting thrust moves in the Z-axis direction with the tool 3 attached. However, the gripper 15 of the ATC magazine 2 may be damaged.

Further, conventionally, there has also been proposed a spindle device in which a pressure switch is provided in an air blow circuit for cleaning the spindle so that the biting state is detected based on the air pressure when the tool is removed. However, since the pressure switch operates after waiting for the air pressure to stabilize, it is necessary to interrupt the ATC operation for a short time during that time, which results in a long ATC time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a spindle device provided with means capable of surely and quickly detecting whether or not a tool bites into a taper hole of a spindle prior to ATC operation.

[0009]

In order to solve the above-mentioned problems, the present invention uses a tool tightening mechanism that pulls up a draw bar by a spring member, closes a collet to press a tool into a tapered hole, and a piston rod of a cylinder. In a spindle device equipped with a tool loosening mechanism that pushes down the drawbar and opens the collet to release the tool, the piston rod is provided with a stroke end that pushes the tool out of the tapered hole through the drawbar for a predetermined distance while the collet is open. Is provided with a signal generator that engages with the dog on the piston rod and generates a tool removal signal when the tool moves to the stroke end.

[0010]

In the spindle device of the present invention, the piston rod is positioned before the stroke end when the collet releases the tool. When the piston rod moves further and reaches the stroke end, if the tool is not biting, the draw bar pushes the tool out of the tapered hole for a predetermined distance, at which time the signal generator engages the dog and the tool removal signal is output. To occur. On the other hand, when the tool is biting, the signal generator does not engage the dog and does not generate the tool removal signal because the piston rod remains stopped before the stroke end. Therefore, based on the movement or stop of the piston rod, the extraction or biting of the tool can be detected reliably and quickly.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIG.
~ It demonstrates based on FIG. The spindle device of the present embodiment is installed in, for example, a vertical machining center as shown in FIG. 5, and has a tool tightening mechanism and a tool loosening mechanism as in the conventional case. As shown in FIG. 1, the tool tightening mechanism is configured such that a drawbar 6 is pulled up by a disc spring 5 as a spring member, a collet 7 is closed, a pull stud 8 is gripped, and a taper shank 9 is press-fitted into a taper hole 10. Has been done. Further, as shown in FIG. 2, the tool loosening mechanism pushes down the draw bar 6 by the piston rod 12 of the cylinder 11, opens the collet 7, and pulls the stud 8.
Is designed to be released.

The cylinder 11 of this embodiment is constructed so that the piston rod 12 can be further moved after the collet 7 is opened. That is, as shown in FIG. 2, the piston rod 12 has a stroke end e.
Then, this stroke end e is connected to the piston rod 12
3, the projection 6a of the drawbar 6 hits the pull stud 8, and the taper shank 9 is pushed out from the taper hole 10 by a predetermined hitting allowance d. At this time, since the tool 3 is gripped by the gripper 15 (see FIG. 5) of the ATC device or the replacement arm, the striking allowance d is set to an allowable bending range of the gripper 15, for example, 1 mm. .

On the threaded portion 12a of the piston rod 12,
A disc-shaped dog 16 is screwed via a washer 17 by a nut 18 so that its position can be adjusted. A high-accuracy limit switch 20 as a signal generator is mounted on the cap 11a of the cylinder 11 via a bracket 19, and its contact 2
0a faces the dog 16 from below. The high-precision limit switch 20 is provided on the piston rod 12
At the stroke end e, the dog 16 is engaged and a tool removal signal is generated. A stopper 21 for finely adjusting the terminal stop position of the piston rod 12 and a nut 22 for positioning the stopper 21 are screwed to the screw portion 12a.

Next, the operation of the spindle device configured as described above will be described with reference to the flow chart shown in FIG. Figure 5
When a tool change command is output in the machining center shown in, the spindle head 1 is first sent in the X and Z axis directions to
It moves to the TC position (step S1), then the gripper 15 grips the tool 3 (step S2), and in this state, the spindle device executes the tool loosening operation (step S).
3).

In loosening the tool, in the state shown in FIG. 1, the piston rod 12 descends, and as shown in FIG. 2, the collet 7 is opened via the draw bar 6 to release the pull stud 8. At this point, the piston rod 12 is positioned before the stroke end e, so that the dog 16
Does not engage the precision limit switch 20. When the piston rod 12 further moves and reaches the stroke end e, if the tool 3 does not bite, the projection 6a of the drawbar 6 hits the pull stud 8 to taper the taper shank 9, as shown in FIG. Only the tap margin d is pushed out from the hole 10. Then, at this time, the high-precision limit switch 20 engages with the dog 16 to generate a tool removal signal.

When this tool extraction signal is confirmed (step S4), the spindle head 1 moves up in the Z-axis direction (step S5), and then the ATC magazine 2 executes the next cycle such as indexing the next tool. Therefore, after confirming that the tool does not bite, move the spindle head 1 to move the gripper 1
It is possible to prevent equipment damage such as item 5 in advance.

On the other hand, when the tool 3 bites into the taper hole 10, the piston rod 12 moves toward the stroke end e.
2 remains stopped (state of FIG. 2), the high-precision limit switch 20 does not engage with the dog 16 and does not generate a tool extraction signal. In this case, it is determined that the tool has been removed incorrectly (step S4), the number of times is counted by the counter (step S6), and this count value is compared with the set value (step S7). If the count value exceeds the set value,
An alarm is generated and A
The TC operation is immediately stopped (step S8). Also,
If the count value is less than the set value, the spindle device once executes the tool tightening operation for retry (step S
9) Then, the tool loosening operation is executed again (step S).
3).

As described above, according to the spindle device of this embodiment, it is determined whether the tool 3 bites into the tapered hole 10 based on the movement or stop of the piston rod 12.
Prior to the C operation, it can be detected reliably and promptly. In addition, if the tool 3 has been bitten, the ATC operation can be advanced by canceling the biting state by retrying several times without leaving it, and if the tool 3 still cannot be pulled out, the ATC operation is stopped. It can be stopped immediately to prevent equipment damage.

The present invention is not limited to the above-described embodiment. For example, a coil spring may be used instead of a disc spring, a proximity switch or a photoelectric tube may be used as a signal generator, and an exchange arm type machining center may be used. It is also possible to embody the present invention by appropriately changing the shapes and configurations of the respective parts within a range not departing from the spirit of the present invention, such as application to a horizontal machining center or a horizontal machining center.

[0020]

As described above in detail, according to the present invention, the piston rod pushes the tool out of the tapered hole at the stroke end, and the signal generator outputs the tool withdrawal signal based on the movement of the piston rod at this time. Since it is configured to occur, whether or not the tool bites into the taper hole of the spindle can be reliably and promptly detected prior to the ATC operation, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing a spindle device of an embodiment according to the present invention in a tool tightened state.

FIG. 2 is a partially omitted sectional view showing the spindle device of FIG. 1 in a tool loosened state.

FIG. 3 is a partially omitted sectional view showing the spindle device of FIG. 1 in a tool withdrawn state.

FIG. 4 is a flowchart for explaining the operation of the spindle device of FIG.

FIG. 5 is a perspective view of a machining center explaining an ATC operation.

FIG. 6 is a sectional view showing a conventional spindle device.

[Explanation of symbols]

1 ... Spindle head 2, ATC magazine 3, Tool 4
..Spindles, 5 ... Disc springs, 6 ... Drawbars, 7 ... Colettes, 8 ... Pull studs, 9 ... Taper shank,
10 ··· Tapered hole, 11 · · Cylinder, 12 · · Piston rod, 16 · · Dog, 20 · · High precision limit switch, 21 · · Stopper, e · · Stroke end,
d ...

Claims (1)

[Claims] 1. A spring member pulls up a draw bar,
In a spindle device that has a tool tightening mechanism that closes the collet and presses the tool into the tapered hole, and a tool loosening mechanism that presses down the drawbar by the piston rod of the cylinder and opens the collet to release the tool, the piston rod opens the collet. With a stroke end that pushes the tool a predetermined distance from the tapered hole through the draw bar in this state, a signal generator that engages with the dog on the piston rod and generates a tool extraction signal is provided when the piston rod moves to the stroke end. Spindle device characterized by: