JP2003291048A - Main shaft for machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent heat generated by cutting from being transferred to a main shaft by directly blowing air to a tool from a tip end of a main shaft for cooling the tool. <P>SOLUTION: A cooling air passage 30 extending along a tapered hole 16 of the main shaft 10 and having a blow out opening 32 on a main shaft end surface is formed inside of a tip part of the main shaft. Air is introduced from an air passage 20 in the main shaft to the cooling air passage 30 and air for cooling the tool is jetted out from a blow out opening 32 toward the tool 14. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a spindle of a machine tool such as a horizontal boring and milling machine.

[0002]

2. Description of the Related Art Thermal displacement due to a temperature rise of a spindle and a spindle head has a great influence on the machining accuracy of a machine tool.

Most of the changes in positioning accuracy in NC machine tools are due to thermal displacement of the spindle and spindle head. Further, since the position accuracy of the spindle is also a relative relationship between the work and the tool, there is a problem that no matter how much the spindle positioning accuracy is increased, the machining accuracy is not substantially improved as long as thermal displacement occurs.

The main shaft expands not only in the axial direction but also in the radial direction. The thermal expansion in the axial direction adversely affects the machining accuracy as described above, but in the case of the main shaft of a horizontal boring and milling machine, the structure that allows the main shaft to be extended due to the existence of a slight gap between the main shaft and the milling shaft. When thermal expansion occurs in the main shaft in the radial direction, it becomes impossible to move the main shaft in the axial direction, the machine stops, and automatic operation cannot be performed.

Various measures have conventionally been taken against the thermal displacement and thermal expansion of the spindle. For example, various attempts have been made to circulate cooling oil in the main shaft to cool it, or to use a material having a small thermal expansion coefficient in the main shaft.

[0006]

However, the heat that causes thermal displacement and thermal expansion is considered to be cutting heat when performing continuous cutting for a long time without using a cutting agent in addition to the bearing of the main shaft and the like. This cutting heat is transmitted from the tool to the spindle, causing the spindle to thermally expand.

When cutting with a cutting agent, the cutting agent directly cools the tool, so there are few problems,
In recent years, there has been a tendency to refrain from using cutting agents that have a large impact on the environment as much as possible.Therefore, measures against thermal expansion due to the transfer of cutting heat generated during cutting without using cutting agents to the spindle Although it is becoming more and more important, the current situation is that sufficient measures have not been taken.

For example, a hose or the like is provided outside the main shaft, and air is blown to the tool from a nozzle at the tip of the hose to cool the tool. However, in the case of a horizontal boring machine, the main shaft is There is a problem that the tool cannot be sufficiently cooled because it cannot follow the feeding movement.

Therefore, an object of the present invention is to solve the problems of the prior art and to blow air directly to the tool from the tip of the spindle, thereby cooling the tool and transmitting cutting heat to the spindle. It is to provide a spindle of a machine tool designed to prevent

[0010]

In order to achieve the above object, the invention according to claim 1 is a spindle of a machine tool having a taper hole in which a tool shank of a tool is mounted at the tip of the spindle. A cooling air passage extending along the taper hole and having an outlet on the end face of the spindle is formed inside the tip of the spindle, and air is introduced from the air passage inside the spindle into the cooling air passage, and air is introduced from the outlet. It is characterized in that it is designed to be ejected toward a tool.

According to a second aspect of the present invention, in the first aspect of the invention, the air passage inside the main shaft extends axially in the center of the draw bar and collet housed inside the main shaft, and is supplied from outside the main shaft. Is an air blow passage for ejecting the air to the taper hole from the air outlet opening to the collet.

Further, the invention according to claim 3 is the same as claim 1.
In the invention described above, the outlet on the end face of the spindle is opened at a mounting portion of a key that engages with a key groove of the tool, and the key is formed with a passage for guiding the air blown from the outlet to the tool. Is characterized by.

In the above invention, it is preferable that a throttle is provided at the air outlet of the main shaft end face in order to enhance the cooling effect by adiabatic expansion.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a spindle of a machine tool according to the present invention will be described below with reference to the accompanying drawings.

First Embodiment FIG. 1 is a vertical sectional view showing a first embodiment in which the present invention is applied to a main shaft of a horizontal boring and milling machine. In these drawings, reference numeral 10 indicates a main shaft (boring shaft), and 12
Is a milling shaft with which the main shaft 10 is fitted. Spindle 1
No. 0 is adapted to be able to pay out the main shaft 10 by being slidably fitted in the milling shaft 12 in the axial direction. The milling shaft 12 is rotatably supported in a ram housing 13 via bearings.

A taper hole 16 for mounting the tool 14 is formed at the tip of the main shaft 10. Tool 14
The arbor portion 15 includes an arbor portion 15 and a tool shank portion 17, and the arbor portion 15 is formed with a flange portion 15a having a groove so that the arbor portion 15 can be gripped by an arm of an automatic tool changing device. In this embodiment, the arbor unit 15 holds an end mill (not shown). Tool shank part 1
A pull stud 19 is attached to the end of 7.

A draw bar 20 is coaxially housed inside the main shaft 10, and a slit type collet chuck 22 is connected to the tip of the draw bar 20. The collet chuck 22 has a known structure generally used for gripping a pull stud of a tool by a spindle of a machine tool. A rod member 23 is inserted and attached to the tip of the draw bar 20, and the rod member 23 is biased toward the tip by a coil spring 24.

An air passage 26 extending in the axial direction is formed inside the drawbar 20. The air passage 26 extends to the rod member 23, and an air outlet 27 is opened at the tip of the rod member 23.
The air outlet 27 includes a not-shown notch formed on the side of the tip of the rod member 23.

This air passage 26 has been conventionally provided, and air of a predetermined pressure is introduced from an air circuit of the spindle head (not shown), and originally, when the tool 14 is removed,
The air is blown from the air outlet 27 to the tapered surface of the tapered hole 16 to prevent foreign matter from adhering to the tapered surface. By blowing the air in this way, it is possible to prevent foreign matter from being caught between the tool shank 17 and the tapered surface of the tapered hole when the tool is replaced with the next tool.

In the inner diameter portion of the main shaft 10, the tapered hole 1
A stepped inner diameter portion 28 is formed adjacent to 6 to surround the pull stud 19.

In the embodiment of the present invention, two tool cooling air passages 30 (only one is shown in FIG. 1) extending along the tapered hole 16 are formed at the tip of the main shaft 10. The air inlet 3 of this tool cooling air passage 30
1 is open to the stepped inner diameter portion 28, and the outlet 32 is
It is formed on the end face of the spindle. As shown in FIG. 1, it is preferable that the blowout port 32 be opened at the seating surface of the mounting portion of the key 34 at the end face of the spindle. On the other hand, the key 34 is formed with a passage 35 for guiding the blown air to the tool 14.

The cooling action of the present embodiment configured as described above will be described.

When exchanging the tool 14 for the spindle 10,
The air supplied to the air passage 26 inside the drawbar 20 is fed from the outlet 27 at the tip of the rod member 23 to the tapered hole 16
Thus, the foreign matter on the tapered surface is blown away, and when the tool 14 is replaced with a new tool 14, the foreign matter is kept clean so as not to be caught in the tool shank portion 17.

On the other hand, when the tool 14 is mounted on the spindle 10 and is being cut by the tool 14, the pull stud 19 of the tool 14 is in contact with the tip of the rod member 23. . The air supplied to the air passage 29 inside the drawbar 20 is jetted from the blowout port 27 to the stepped inner diameter portion 28 from a notch portion (not shown) on the side surface, and the air introduction port 31 opened to the stepped inner diameter portion 28. Will be introduced to. Therefore, the air flows through the tool cooling air passage 30 and is ejected from the outlet 32 toward the tool 14.

At this time, if the workpiece is processed without using a cutting agent, the cutting heat generated from the cutting edge of the tip of the end mill is transferred to the arbor portion 15 during the processing. Since air is blown directly from the air outlet 32 to the arbor portion 15 of the tool 14 to remove heat,
It is possible to prevent heat from being transferred to the main shaft 10 without providing an air nozzle or the like outside as in the conventional case. Therefore, it is effective in preventing thermal displacement due to the axial extension of the main shaft 10, and if the main shaft 10 is the boring shaft as in this embodiment, the main shaft 10 expands in the radial direction, and It is possible to prevent a problem that a gap required for the unwinding operation of the main shaft 10 from the outer milling shaft 12 disappears.

Further, according to the present embodiment, the air outlet 32 is opened to the seating surface of the key 34, and the key 43 itself has a passage 35 for guiding air to the tool 14. The blown air is concentrated and blown on the arbor portion 15 of the tool 14 without being scattered around the tool 14, so that the cooling efficiency can be further enhanced. Moreover, since the passage 35 may be worked in the key without processing on the main shaft side, the processing applied to the end surface of the main shaft can be minimized.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.

The second embodiment is different from the first embodiment in that the throttle 40 is provided at the air outlet 32 of the tool cooling air passage 30.
That is the point. The other components are the same as those in the first embodiment, and the same components are designated by the same reference numerals and the description thereof will be omitted.

According to the second embodiment, when the air is blown out from the air outlet 32 of the tool cooling air passage 30, the temperature is lowered due to adiabatic expansion by passing through the restrictor 40, so that the tool is further improved. The cooling effect of 14 can be enhanced.

As the cooling medium blown out toward the tool 14, an oil mist sent to the main shaft bearing for lubricating and cooling the main shaft bearing (not shown) may be used. In this case, the oil mist unit may be connected to the circuit in the spindle head that supplies air to the air passage 29 inside the drawbar 20 by an electromagnetic switching valve. By using the oil mist as the cooling medium, the blade edge can be lubricated at the same time when the tool 14 is cooled.

[0031]

As is apparent from the above description, according to the present invention, air can be blown directly from the tip of the spindle to the tool to cool the tool and prevent the cutting heat from being transmitted to the spindle. It is possible to effectively prevent the cutting heat generated during cutting performed without using a cutting agent from being transmitted to the spindle.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main shaft of a horizontal boring and milling machine according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a main shaft of a horizontal boring and milling machine according to an embodiment of the present invention.

[Explanation of symbols]

10 spindles 12 milling axes 13 Ram housing 14 tools 15 Arbor 17 Tool shank 19 pull studs 20 drawbars 22 Collet chuck 23 Rod member 26 Air passage 27 Outlet 30 Tool cooling air passage 32 outlet 34 key 35 passage 40 aperture

Claims (6)

[Claims] 1. A spindle of a machine tool having a taper hole in which a tool shank of a tool is mounted at a tip of a spindle, wherein a cooling air passage extending along the taper hole of the spindle and having a blowout port on an end face of the spindle is provided at the tip of the spindle. A spindle of a machine tool, wherein the spindle is formed inside the portion, and air is introduced into the cooling air passage from an air passage inside the spindle so that the air is ejected toward the tool from the blowout port. 2. An air passage inside the main shaft extends axially in a central portion of a draw bar and a collet housed inside the main shaft, and air supplied from outside the main shaft is opened to the collet from a taper hole. The spindle of a machine tool according to claim 1, wherein the spindle is an air blow passage for ejecting the air toward the shaft. 3. The outlet on the end face of the spindle is opened at a mounting portion of a key that engages with a key groove of a tool, and the key has:
The spindle of a machine tool according to claim 2, wherein a passage is formed to guide the air blown out from the outlet to the tool. 4. The spindle of a machine tool according to claim 1, wherein a throttle is provided at the air outlet of the spindle end surface. 5. The spindle of a machine tool according to claim 1, wherein the spindle is a boring shaft of a boring machine. 6. The spindle of a machine tool according to claim 1, wherein an oil mist for lubricating the spindle bearing is used as the cooling medium instead of the air.