JPH06106447A - Machine tool and cooling of machine tool - Google Patents

Abstract

PURPOSE:To shorten idling time until a relative change in bite height can be stabilized, and obviate reidling caused by a change in the number of revolutions of a main shaft and readjustment of the bite height. CONSTITUTION:A refrigerant 65 in a tank 66 is supplied to a main shaft stand 6, and the refrigerant 65 whose temperature is raised after the main shaft stand 6 is cooled is supplied to an X axis table 5 and a circular table 8, and is flowed back to the tank 66 from the tables 5 and 8. Thereby, since the refrigerant is supplied to the main shaft stand and the refrigerant whose temperature is raised after the main shaft stand is cooled is supplied to the tables, The temperature of the tables is raised and is maintained at the same temperature (or constant temperature difference) as the main shaft stand, and relative dislocation between the main shaft stand and the tables can be prevented. Thereby, idling time can be shortened, and adjustment of bite height caused by a change in the number of revolutions of a main shaft can be obviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machine tool cooling method and a machine tool for high precision and ultra precision machining.

[0002]

2. Description of the Related Art As is well known, a machine tool has a headstock having a spindle, and a table for machining a workpiece by moving it relative to the headstock. In a lathe, a table having a cutting tool is moved relative to a headstock having a spindle that grips and rotates a work, and the work is processed by the cutting tool. . Particularly in the machining mainly for the end face cutting, the peripheral speed of the cutting is close to 0 in the central part of the work, so that it is a problem to make the finishing quality similar to that of the outer peripheral part.

However, in a lathe for high-precision or ultra-precision machining, the headstock is thermally displaced by the heat generated by the rotation of the spindle, causing a height difference between the center of the spindle (workpiece) and the height of the cutting tool. Also, due to the difference in heat capacity due to the change in room temperature, there may be a difference in height between the center of the spindle and the height of the cutting tool. The height difference due to such a change over time gives a change over time in the entry angle of the cutting tool with respect to the center of the work, not only deteriorating the quality of the finished surface, but in the worst case, a bellows shape in the center. It causes defects as uncut parts. Especially on a lathe that processes the end face of a workpiece with high precision and ultra precision, such as machining a spherical surface, aspherical surface, or flat surface of a lens, etc., the high and low levels that occur over time between the center of the spindle and the cutting point of the cutting tool. The difference becomes a big problem.

Conventionally, an automatic adjustment mechanism using a piezoelectric element has been used to eliminate the above-mentioned change in height difference over time, but this is extremely expensive and not practical, and is generally used. In this case, the tool is allowed to idle for a long time (3 hours or more) until the relative displacement in the height direction becomes stable, and in this state, the height of the cutting tool is finely adjusted for processing. Also, when the rotational speed of the spindle is changed, the temperature of the headstock changes and the relative displacement in the height direction also changes.Therefore, if the rotational speed is changed, restart the idling height for a long time again after changing the rotational speed. I had to make an adjustment.

[0005]

The above-mentioned prior art requires a long idling time. When the spindle speed is 3,000 rpm and 5,000 r
Relative displacement difference of about 2 times occurs when processed with pm,
It was necessary to change the bite height. By the way, although the spindle drive motor and the vicinity of the spindle bearing have been partially cooled in the past, this method basically solves the occurrence of the time-dependent change in height between the spindle center and the bite height. Has not arrived.

It is an object of the present invention to shorten the idling time until the relative change in the bite height stabilizes, and to cool the machine tool without the necessity of re-idling and re-adjusting the bite height with a change in the spindle speed. A method and a machine tool are provided.

[0007]

A method of cooling a machine tool according to the present invention for achieving the above object comprises a headstock and a table for moving a workpiece relative to the headstock. In a machine tool equipped with, the refrigerant in the tank is supplied to the headstock, and the temperature-increased refrigerant after cooling the headstock is supplied to the table and is returned from the table to the tank.

A machine tool of the present invention for achieving the above object is a machine tool including a headstock and a table which moves relative to the headstock to machine a workpiece. Cooling means provided on the table, cooling means provided on the table, a tank containing a refrigerant, and a conduit for returning the refrigerant cooled from the tank to the headstock cooling means and the table cooling means in this order and returning to the tank. It is characterized by having and.

[0009]

The refrigerant supplied to the headstock is heated by the headstock. This heated refrigerant is supplied to the table,
As the temperature of the table rises, the temperature of the table becomes almost the same as that of the headstock 8 or a substantially constant temperature difference). Therefore, relative displacement in the height direction between the headstock and the table is prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows the outline of the overall configuration. As shown in FIG. 1, on a machine bed 1, a Z-axis table 3 moved by a Z-axis driving motor 2 in the Z-axis direction, and an X-axis driving motor in a horizontal X-axis direction orthogonal to the Z-axis. An X-axis table 5 that can be moved by 4 is mounted. A headstock 6 is fixed on the Z-axis table 3, and the headstock 6 is rotated by a built-in spindle driving motor.
have. A circular table 8 which is rotated in the C-axis direction by a C-axis driving motor (not shown) is mounted on the X-axis table 5. Further, on the circular table 8, a Y-axis direction parallel to the Z-axis is set. A Y-axis table 10 that is moved by an axis drive motor 9 is mounted. On the upper surface of the Y-axis table 10, a tool base 13 holding a cutting tool 12 for processing the work 11 held by the main spindle 7 is fixed.

FIG. 2 shows the headstock 6. As shown in FIG. 2, the headstock 6 includes a hollow spindle 7 and a hydrostatic bearing portion 20.
The main shaft 7 is rotatably supported by the main shaft drive motor 21. A spindle chuck 22 for gripping a work is provided at the front end of the spindle 7, and the spindle chuck 22 is a chuck opening / closing cylinder 23 attached to the rear end of the headstock 6 via a chuck opening / closing drawbar 24. Can be opened and closed.

As shown in FIGS. 1 and 2, in this embodiment, as a cooling means for the headstock 6, the headstock 6 is provided below the static pressure bearing portion 20 and the spindle drive motor 21. A refrigerant inlet 30 and a refrigerant outlet 31 are provided on the side surface of the mounting portion of the headstock 6, and the refrigerant inlet 30 and the refrigerant outlet 31 are connected by a refrigerant passage 32. In addition, the spindle drive motor 2
A coolant inlet 33 and a coolant outlet 34 are provided on the upper surface of the headstock 6 corresponding to No. 1, and the coolant inlet 33 and the coolant outlet 34 are connected by a coolant circulation passage 35 formed in a spiral shape.

FIG. 3 shows the circular table 8. As shown in FIG. 3, as a cooling means for the circular table 8, a rotary shaft 41 having its axis vertically disposed is rotatably supported by a table main body 40 of the circular table 8 via a bearing 42 to rotate. A rotary table 43 is fixed to the shaft 41. A gear 44 is fixed to the lower surface of the turntable 43, and a gear 45 meshes with the gear 44. Gear 4
5 is fixed to the output shaft of a circular table driving motor 46 fixed to the table body 40. Therefore, when the circular table driving motor 46 is driven, the rotary base 43 and the rotary shaft 41 are driven via the gears 45 and 44.
Rotates.

As shown in FIGS. 1 and 3, the table body 40 is provided with a refrigerant retention portion 50 around the bearing 42, and the refrigerant retention portion 50 is provided above the refrigerant retention portion 50 so as to communicate with the refrigerant retention portion 50. A refrigerant inlet 51 is provided on the front surface of the. A refrigerant outlet 52 is provided on a side surface below the table body 40, and the refrigerant outlet 52 is communicated with the refrigerant retaining portion 50 by a refrigerant passage 53.

As shown in FIG. 1, as a cooling means for the X-axis table 5, the X-axis table 5 has a refrigerant inlet 6 on the front surface thereof.
0, the refrigerant outlet 61 is provided on the side surface, and the refrigerant passage 62 is provided inside so that the refrigerant inlet 60 and the refrigerant outlet 61 communicate with each other. Since this specific structure is almost the same as the cooling means of the circular table 8, detailed description will be omitted.

A tank 66 containing a refrigerant 65 is disposed on the side surface of the machine bed 1. The refrigerant 65 in the tank 66 passes through a pump 67, a refrigerator 68, and a pipe 69 below the headstock 6. Is supplied to the refrigerant inlet 30 provided in the. The refrigerant outlet 31 below the headstock 6 is connected to the refrigerant inlet 33 above the piping 71 via the flow control valve 70.
And is connected to the pipe 72, which will be described later, by an appropriate amount. Pipe 7 connected to the refrigerant outlet 34
3 extends to tank 66. Further, the refrigerant outlet 31 below the headstock 6 is connected by a pipe 72 to the refrigerant inlet 51 of the circular table 8 and the refrigerant inlet 6 of the X-axis table 5.
0, the refrigerant outlet 52 of the circular table 8
The refrigerant outlet 61 of the X-axis table 5 is connected to the pipe 73 by the pipes 74 and 75.

Next, the operation will be described. The coolant 65 in the tank 66 is pumped up by the pump 67 and cooled to a predetermined temperature by the refrigerator 68. The cooled refrigerant 65 passes through the pipe 69 and the refrigerant inlet 3 of the headstock 6.
Supplied to zero. The refrigerant 65 supplied to the refrigerant inlet 30 of the headstock 6 cools the hydrostatic bearing portion 20 of the main spindle 7 through the refrigerant passage 32, and at the same time, heat passes from the headstock 6 to the Z-axis table 3 through the mounting portion. After preventing the transmission, it flows from the refrigerant outlet 31 to the pipes 71 and 72. The refrigerant 65 flowing in the pipe 71 is supplied to the refrigerant inlet 33 of the headstock 6 through the flow rate control valve 70, and the refrigerant 65 flowing in the pipe 72 is cooled by the refrigerant inlet 51 of the circular table 8 and the X-axis table 5.
Is supplied to the refrigerant inlet 60.

The coolant 65 supplied to the coolant inlet 33 of the headstock 6 flows through the coolant circulation path 35 to the coolant outlet 34,
After cooling the heat generated by the spindle drive motor 9, the pipe 7
It is returned to the tank 66 through No. 3. The refrigerant 65 supplied to the refrigerant inlet 51 of the circular table 8 is supplied to the refrigerant retention part 50, and the entire circular table 8 is cooled to a temperature substantially the same as that of the attachment part of the headstock 6 or a substantially constant temperature difference ( The term of “cooling” in this specification includes heating in some cases), and then flows through the refrigerant passage 53 to the refrigerant outlet 52, and from the refrigerant outlet 52 through the pipes 73 and 71. It is returned to the tank 66. In addition, the refrigerant 65 supplied to the refrigerant inlet 60 of the X-axis table 5
Similarly cools the X-axis table 5, flows through the refrigerant passage 62 to the refrigerant outlet 61, and returns to the tank 66 through the pipes 75 and 73.

Therefore, the temperature of the refrigerant 65 passing through the refrigerant passage 32 of the headstock 6 is raised to almost the same temperature as the mounting portion of the headstock 6 (a temperature difference which is substantially constant when the heat capacity of the refrigerant is insufficient). To be done. This heated refrigerant 65 is pipe 72
The circular table 8 and the X-axis table 5 are supplied to the circular table 8 and the X-axis table 5 and flow into the refrigerant retention section 50 and the refrigerant passage 62, so that the temperature of the circular table 8 and the X-axis table 5 rises to almost the same temperature as the headstock 6. . For this reason,
Headstock 6, circular table 8 and X-axis table 5
Relative displacement due to the temperature difference between and, that is, relative displacement of the cutting tool 12 with respect to the spindle 7 is prevented. As a result, the idling time required to stabilize the relative displacement after the start was 3 hours or more in the related art, but in the present embodiment, it was significantly shortened to 15 minutes. Further, there is a difference in relative displacement between the case of processing at a rotational speed of the spindle 7 of, for example, 3,000 rpm and the case of processing at 5,000 rpm, which is about twice the conventional value, but the rotational speed is changed in this embodiment. Even became stable by not having to change the bite height.

FIG. 4 shows another embodiment of the present invention. In the above-described embodiment, the refrigerant discharged from the refrigerant outlet 31 is supplied to the refrigerant inlet 33 above the headstock 6, but in the present embodiment, the refrigerant is supplied directly to the refrigerant inlet 33 from the pipe 69. Even with this structure, the same effect as that of the above embodiment can be obtained.

The cooling means for cooling the headstock 6 cools the headstock to an appropriate temperature so that the centerline of the headstock does not tilt, and raises the temperature for displacing the centerline of the headstock (in this embodiment, the temperature of the headstock 6 is increased). It is sufficient to raise the temperature of the refrigerant to a temperature corresponding to (the temperature of the mounting portion is substituted), and the table cooling means is
It suffices to supply the refrigerant whose temperature has been raised by the cooling means of the headstock to the table (in the embodiment, the circular table 8 and the X-axis table 5) to which the bite 12 is attached, and maintain this table at a temperature corresponding to the temperature of the refrigerant. However, it is not limited to the structure of this embodiment. It should be noted that the table to be cooled has a displacement approximately the same as the displacement of the spindle center line caused by a change in the temperature of the headstock, and it suffices to select the table and cool it. is not. Although the above description has been made by using the lathe as an example, it is obvious that the same applies to other machine tools such as a milling machine and a machining center.

[0022]

According to the present invention, the refrigerant in the tank is supplied to the headstock, and the temperature-increased refrigerant after cooling the headstock is supplied to the table and is recirculated from the table to the tank.
The temperature of the table rises and is maintained at substantially the same temperature as the headstock (or a constant temperature difference), and relative displacement between the headstock and the table is prevented. As a result, the idling time can be shortened and the adjustment of the bite height due to the change of the spindle speed becomes unnecessary.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an overall configuration showing an embodiment of a machine tool according to the present invention.

FIG. 2 is a sectional view of a headstock.

FIG. 3 is a cross-sectional view of a circular table.

FIG. 4 is a schematic view of an overall configuration showing another embodiment of the machine tool according to the present invention.

[Explanation of symbols]

 5 X-axis table 6 Headstock 8 Circular table 11 Work 30 Refrigerant inlet 31 Refrigerant outlet 32 Refrigerant passage 50 Refrigerant retention part 51 Refrigerant inlet 52 Refrigerant outlet 53 Refrigerant passage 60 Refrigerant inlet 61 Refrigerant outlet 62 Refrigerant passage 65 Refrigerant 66 Tank 69, 71 ~ 75 piping

Claims (6)

[Claims] 1. A machine tool having a headstock and a table for moving a workpiece by moving relative to the headstock, in which a coolant in a tank is supplied to the headstock to cool the headstock. A method of cooling a machine tool, characterized in that a later heated refrigerant is supplied to a table and is circulated from the table to a tank. 2. A machine tool comprising a headstock and a table which moves relative to the headstock to process a workpiece, a cooling means provided on the headstock, and a cooling means provided on the table. A machine tool comprising: a tank containing a refrigerant; and a pipeline for returning the refrigerant cooled from the tank to the cooling means of the headstock and the cooling means of the table in order to return the refrigerant to the tank. 3. The machine tool according to claim 1, wherein the machine tool is a lathe, and the table is a tool post that supports a cutting tool and moves relative to the headstock to machine a workpiece. Cooling method and machine tool. 4. The method of cooling a machine tool according to claim 1, wherein the refrigerant supplied to the table stays inside the table. 5. The machine tool according to claim 2, wherein the cooling means for the table has a refrigerant retention portion for retaining the refrigerant inside the table. 6. The method for cooling a machine tool and the machine tool according to claim 1, wherein the coolant is cutting oil.