JPH0763917B2 - Ultra-precision machine tool - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-precision machine tool that keeps the whole machine tool at a constant temperature and uniformly.

Conventional technology In an ultra-precision machine tool that performs turning on the order of 1/10 μm to 1/100 μm in a machine tool, temperature fluctuations and non-uniformity in the machine greatly affect machining accuracy. Keep the temperature constant, and if necessary, apply an oil shower with constant temperature oil to the entire machine, and replace the sliding bearings and rolling bearings of the machine that generate a large amount of heat with air bearings that use temperature-controlled air. Comprehensive measures are being taken to keep the overall temperature constant and uniform.

One of the difficult problems in such an ultra-precision machine tool is the treatment of heat generated by a motor used for driving force for feeding and rotating.

It is probably possible to develop a special motor with low heat generation for ultra-precision machine tools, but at present, a general-purpose motor with a relatively high heat generation is used in order to remove the heat generated by the motor due to its cost. , Use a heat insulating material such as plastic for the motor mounting seat, or allow air or liquid to flow inside the mounting seat, and do not directly contact the motor shaft with the machine body side shaft Further, the outer surface of the motor is covered with a jacket formed of a heat insulating material with a gap, and the air in the gap is discharged to the outside, and
The outer shell blocks radiation from the outer surface of the motor.

However, in the conventional type, the heat generated by the motor is eventually released to the internal space of the case containing the entire machine tool, which is inefficient in maintaining the machine tool at a constant temperature, and also penetrates deeply into the machine body. The heat transferred from the outer surface of the motor shaft, which is often connected to the shaft on the main body side, to the machine main body is not considered, and satisfactory temperature control cannot be performed.

Problems to be Solved by the Invention An object of the present invention is to greatly improve the heat countermeasure for the motor, which has been a bottleneck in the conventional temperature control described above.

Means for Solving the Problem The machine tool is housed in a case that covers the entire machine, and the motor connected to the machine tool is covered with an outer jacket made of a heat insulating material to provide a discharge space communicating with the outer circumference of the motor to the outside of the case. The front surface of the motor is fixed to the motor support portion of the machine tool through a heat insulator, and the motor shaft is arranged with a gap between the support portion and the heat insulator, and the heat insulator internally has an air pocket and a jet air supply path. The air pocket is provided with a jet hole opening to the discharge space and a nozzle facing the jet hole on the inner wall at a position facing the discharge hole, the nozzle facing the jet hole, and the heat insulator and the motor. A communication gap that is positively formed at the contact point is used to communicate with the space around the motor shaft.

The jet air from the nozzle draws out the air in the air pocket to the exhaust space by the Venturi effect when passing through the ejection hole, and the pressure reduction at that time sucks the air around the motor shaft through the communication gap and positively the air around the motor shaft. Flow and discharge it to the outside.

The air in the discharge space is quickly discharged to the outside of the case by the pressure of jet air.

Example FIG. 2 shows an example of an ultra-precision machine tool to which the present invention is applied. The machine tool 1 is housed in a synthetic resin case 2 which can be opened and closed and whose upper part is transparent, and is substantially shielded from the external environment during operation. It is supposed to be done. Although not shown, this machine tool has an external auxiliary device such as a constant temperature air supply device for the inside of the case, a constant temperature pressure air supply device for air bearings and air joints, and an oil circulation device for a constant temperature oil shower, if necessary. Is attached, and a comprehensive system that maintains the temperature of the entire machine tool at a constant temperature is configured.

As shown in FIGS. 3 and 4, the illustrated machine tool 1 includes a headstock 4 movable in the Z direction with respect to the base 3, a tool base 5 movable in the X direction in front of the headstock 4, and a tool base 5 movable on the right. A rotary table 6 that rotates horizontally is provided. An extendable cover 7 is provided in a region where the headstock 4 and the tool rest 5 move in the Z-axis and X-axis directions in order to protect the sliding surface with the base 3 from chips and the like.

The headstock 4 is Z mounted on the base 3 by the Z-axis servomotor M1.
It is moved by driving the shaft feed screw 8, and the tool rest 5 moves to X
It is moved by driving the X-axis feed screw 9 mounted on the base 3 by the axis servo motor M2. The spindle 10 in the spindle stock 4 is driven by the spindle motor M3, and the rotary table 6 is rotated by driving the worm 11 by the table rotation servomotor M4. The bearings of each shaft and the slide surface of the headstock 4 and the tool stand 5 with respect to the base 3 have a similar structure using a static pressure air bearing, a static pressure air support surface, or a static pressure of oil to suppress heat generation and control movement. Smoothness is achieved. And the whole machine tool is an air damper for vibration isolation.
It is placed and fixed on the bottom of the case 2 via 12.

The work 13 attached to the spindle 10 is an aspherical mirror used for laser equipment, and the rotary table 6 is a diamond tool.
14 is attached.

As shown in FIG. 1, the above-mentioned motors M1 to M4 (motor M
Or at least the spindle motor M3 and the table rotation servomotor M4 are covered with an outer casing 15 made of a heat insulating material such as synthetic resin, and a support portion on the machine tool side is provided via a plate-shaped heat insulating body 16. (For the motors M1 and M2, the mounting parts of these motors on the base 3 are meant, for the motor M3, the motor mounting parts of the headstock 4 and, for the motor M4, the motor mounting parts of the tool base 5 ...
(Represented by) is bolted to.

A discharge space is provided between the outer jacket 15 and the outer surface of the motor M.
A jet air supply path 19 and an air pocket 20 are formed inside the heat insulating body 16. The jet air supply passage 19 is connected to the jet air supply passage 21 on the side of the support portion 17, and the air pocket 20 is provided with an ejection hole 22 that opens into the discharge space 18, and the inner wall portion facing the ejection hole 22 is provided with the above-mentioned. Nozzle 23 communicating with jet air supply passage 19 is a jet hole
It is provided toward 22. The air pocket 20 also communicates with a space 26 around the motor shaft 25 by a communication gap 24 that is positively formed in a portion where the heat insulator 16 and the front surface of the motor M contact each other. A plurality of ejection holes 22 and nozzles 23 are provided along the periphery of the motor M, and the jet air supply passage 19 and the communication gap 24 are provided.
The air pockets 20 are formed in a radial shape while also functioning as a cooling for the heat insulating plate 16 by passing air, and are formed in an annular shape. When the amount of heat generated by the motor is large, the heat insulator 16 may be provided with a second jet hole 22 'for jetting air directly from the jet air supply passage 19 to the discharge space 18 in addition to the jet hole 22. .

The motor shaft 25 is connected to the feed screws 8 and 9, the main shaft 10 and the worm 11 via an air joint 27. Reference numeral 28 is a support portion
The static air pressure supply passage formed in 17 communicates with a small space 29 that constitutes the static pressure air bearing of the bearing portion.

Note that the air supply to the jet air supply path 19 and the static air pressure supply path 28 is performed by a separate system because the required conditions are different, and a constant temperature liquid is supplied to the jet air supply path 19 instead of air. It may be done.

A cover cylinder 30 which is freely stretchable and bendable is attached to the rear of the outer jacket 15 to directly communicate the discharge space 18 to the outside of the case 2.

When turning, close Case 2 and operate the above-mentioned integrated system for maintaining a constant temperature.
The temperature-controlled compressed air is supplied to 21 (supporting portion side), and is ejected from the nozzle 23 toward the ejection hole 22 via the jet air supply passage 19 inside the heat insulator 16 while each motor M1 to
Drive M4 with NC and other prescribed controls. Spindle motor
The M3 and the table rotation servomotor M4 move as the headstock 4 and the tool base 5 move while being connected to the case by the cover pipe 30, but the cover pipe 30 is expandable and contractible, so the headstock 4 and the tool base 5 are movable. There is no support for the move. By the above-mentioned integrated system, heat generation from the shaft support portion and slide portion in the machine body is suppressed, and the heat generated by the motor is discharged to the outside to keep the temperature inside the case and the temperature of the machine body constant. The jet air from the nozzle 23 also pulls out the air inside the air pocket 20 due to the Venturi effect when passing through the ejection hole 22, and causes the air in the space 26 around the motor shaft 25 to pass through the communication gap 24 to the one shown in FIG. Forced air pockets 20 to show air flow with dashed lines
The air in the space 26 is exhausted to the exhaust space 18 without accumulating, and the heat moving from the motor shaft 25 to the machine body is removed. At the same time, the discharge space 18 in contact with the outer surface of the motor
The air is also forcibly discharged to the outside through the cover tube 30 together with the heat of the motor by the action of the jet air.

Effect of the Invention The heat generated by the motor is directly discharged to the outside of the case and does not affect the machine body of the machine tool. In particular, the heat around the motor shaft that has entered the machine body is also removed, so that the effect of heat generated by the motor can be removed at a level close to perfection.

The jet air ejected from the nozzle has a function of sucking the air around the motor shaft and pushing the air in the discharge space 18 to the outside, so that the energy of the jet air can be used without waste.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part, FIG. 2 is a perspective view, FIG. 3 is a plan view showing a cover of a case, and FIG. 4 is a schematic vertical cross-sectional view. 1 ... Machine tool, 2 ... Case, 3 ... Base, 4 ...
Spindle base, 5 ... Tool base, 6 ... Rotary table, 7 ... Cover, 8 ... Z-axis feed screw, 9 ... X-axis feed screw, 10 ...
Spindle, 11 …… Worm, 12 …… Air damper, 13 …… Workpiece, 14 …… Diamond tool, 15 …… Coat, 16 ……
Insulation, 17 ... Support, 18 ... Discharge space, 19 ... (Insulation) jet air supply path, 20 ... Air pocket, 21 ...
… Jet air supply path (on the support side), 22… Jet holes,
23 …… Nozzle, 24 …… Communication gap, 25 …… Motor shaft, 26…
… Space around motor shaft, 27 …… Air joint, 28 …… Aerostatic pressure supply path, 29 …… Slight space, 30 …… Cover cylinder, M1…
… Z-axis servo motor, M2 …… X-axis servo motor, M3 ……
Spindle motor, M4 ... Table rotation servo motor.

Claims (1)

[Claims] 1. A machine tool is housed in a case that entirely covers the machine tool, and each motor of the machine tool is covered with an outer jacket made of a heat insulating material and provided with a discharge space communicating with the outer circumference of the motor.
The front surface of the motor is fixed to the motor support portion of the machine tool via a heat insulator, and the motor shaft is arranged with a gap from the support portion and the heat insulator, and the heat insulator has an air pocket and a jet air supply passage inside. The air pocket is provided with a jet hole that opens into the discharge space and a nozzle that is connected to the jet air supply path and faces the jet hole on the inner wall facing the jet hole. An ultra-precision machine tool characterized by being communicated with the space around the motor shaft by means of a communication gap that is positively formed at the contact point.