JP2014012324A - Precision machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precision machine tool capable of efficiently pouring a coolant to a column, which is thermally stabilized regardless of fluctuations of environmental temperature changes thereby effectively suppressing thermal displacement, and draining the coolant therefrom.SOLUTION: In a precision machine tool, a spindle head 20, which may move in a vertical direction, is provided in a column 14 erected on a bed 10, and a coolant storage space, in which a temperature is controlled, is formed in the column 14. A lower part of the column 14 includes water inlet ports 38a, 38b for introducing a coolant to the coolant storage space, and an upper part of the column 14 includes a first drain port 40 for leading out the coolant to the exterior. The water inlet ports 38a, 38b serve as second drain ports for draining an entire amount of the coolant from the column 14.

Description

  The present invention relates to a precision machine tool, and more particularly to a precision machine tool that performs ultra-precision machining of a mold or the like for molding an optical component such as a lens.

  In recent years, vertical, horizontal, and gate-shaped precision machine tools or lathes that process high-precision precision molds for molding parts that require high processing accuracy, such as reflectors and lenses for optical equipment. Precision machine tools such as are being developed.

  For example, a portal machine tool will be described as an example. A portal machine tool is a machine tool having a portal column in which cross rails are horizontally stretched over columns erected on both sides of a bed. A table is provided between the left and right columns, and a saddle holding the spindle head is movably provided on the cross rail.

  Conventional portal machine tools were generally large machine tools that process large and long workpieces, but in recent years, small portal precision machine tools capable of high-precision machining have been developed. Yes. This portal precision machine tool processes precision molds used for manufacturing precision parts related to precision machines and parts for optical equipment.

  For example, in the processing of molds used for molding optical parts such as reflectors and lenses, in order to process the mold surface into a highly accurate mirror surface, submicron or nanometer order precision is required. . When machining a mold with such a high-precision mirror surface, the machining finishing time will inevitably become longer, so the environmental temperature change from the start to the end of machining will not affect the machining accuracy. There is a need to. A similar need arises for vertical and horizontal precision machine tools and lathes.

  Generally, in machine tools, heat generation of the motor and guide surfaces and room temperature fluctuations cause thermal deformation of the bed and column. Therefore, piping for cooling water is provided in the column and bed as a countermeasure against thermal deformation. . For example, as a conventional technique for cooling a column, for example, column cooling structures described in Patent Documents 1 and 2 can be cited.

  In the case of a portal precision machine tool or a vertical precision machine tool, the cutting direction of the tool (Z-axis) is the same as that of the column, and if the column is thermally deformed due to the influence of temperature fluctuations, the machining accuracy will drop quickly. As a result, it becomes impossible to perform ultra-precision machining like a mirror surface.

  Conventionally, precision machine tools, like other processing machines, have been equipped with a cooling device that supplies cooling water to the heat generating parts such as the motor that drives the shaft and the guide surface. However, since only a part of the column can be cooled, the effect is low in ultra-precision machining.

  In order to solve this problem, a precision machine tool is installed in a temperature-controlled room, or the temperature in a cover surrounding the machine is controlled. However, in such a temperature-controlled room, it is not always sufficient to suppress the column's thermal displacement caused by the heat generated from the machine tool itself and environmental temperature changes to such an extent that ultra-precision machining is possible. The equipment was very expensive.

  In order to solve such problems, the present applicant proposes that the column itself is configured as a tank for storing cooling water, and that the column that is most susceptible to changes in environmental temperature is thermally and effectively stabilized. (Japanese Patent Application No. 2012-037304).

JP-A-5-309536 JP-A-6-126564

Originally, a column is a structure that is not planned to be used as a tank, and various new problems arise when the interior of the column is filled with cooling water.
For example, in order to fill the column with cooling water, it is necessary to form cooling water intakes and drain openings. How to install these intakes and drain openings in the column depends on the cooling effect and efficiency of drainage. And so on.

  The present invention has been made in connection with the invention in which the column also serves as a tank filled with cooling water. The column is thermally stabilized regardless of fluctuations in the environmental temperature change, thereby effectively preventing thermal displacement. The object is to provide a precision machine tool capable of efficiently injecting and draining cooling water to the column to be suppressed.

  In order to achieve the above object, according to the present invention, a spindle head that is vertically movable is provided on a column that is erected on a bed, and a temperature-controlled cooling water storage space is provided inside the column. In the precision machine tool in which is formed, a lower part of the column has a water intake port through which cooling water is introduced into the water storage space, and an upper part of the column has a first drain port for leading the cooling water to the outside. And the intake port also serves as a second drain port for extracting the entire amount of cooling water from the inside of the column.

It is a perspective view which shows the portal precision machine tool to which this invention is applied. It is a front view of the portal column of a portal precision machine tool. It is a longitudinal cross-sectional view of the portal column shown in FIG. It is a systematic diagram of the cooling water system of the portal precision machine tool. It is a figure which shows the cooling water system | strain of the horizontal precision machine tool by 2nd Embodiment of this invention.

Embodiments of a precision machine tool according to the present invention will be described below with reference to the accompanying drawings.
First embodiment
FIG. 1 shows a portal precision machine tool to which the present invention is applied. In FIG. 1, reference numeral 10 indicates a bed. A table 12 is installed on the bed 10 so as to be movable in the front-rear direction along the guide surface 11. Reference numeral 14 denotes the entire portal column. The portal column 14 includes a column 15 that is arranged on the left and right of the table 12 and stands vertically, and a cross rail 16 that extends horizontally between the columns 15 and 15. In this embodiment, the portal column 14 is a casting in which the columns 15 and 15 and the cross rail 16 are integrated. The detailed structure of the portal column 14 will be described later.

  A saddle 17 is installed on the upper surface of the cross rail 16 so as to be movable in the left-right direction along the guide surface 18. The saddle 17 holds a spindle head 20, and the spindle head 20 is provided with a spindle 22 that moves in the vertical direction. This double precision machine tool is a machine that performs ultra-precise machining of submicron or nanometer order on a workpiece. The main shaft 22 is supported by a high-speed air bearing and can rotate at a super-high speed of 120,000 / min at the maximum.

  In such a portal precision machine tool, the X-axis is an axis that controls the movement of the table 12, the Y-axis is an axis that controls the movement of the saddle 17, and the X-axis and the Y-axis are on the horizontal plane of the tool. Perform positioning. The Z axis is an axis for positioning the main shaft 22 in the vertical direction, and mainly controls the cutting amount of the tool.

  In the case of a portal precision machine tool, the main shaft 22 is positioned in the vertical direction on the saddle 17 that moves on the guide surface 18 of the cross rail 16, and this guide surface 18 serves as a so-called reference surface for positioning. On the other hand, since the height difference between the guide surface 18 and the workpiece on the table 12 is large in the portal column 14, if the column 15 or the cross rail 16 constituting the portal column 14 is thermally deformed, the tool This greatly affects the vertical positioning accuracy. In the case of ultra-precise machining in submicron or nanometer units, it takes a long time to finish finishing such as mirror finishing. In the meantime, heat continues to be generated from each part of the machine tool, and the temperature environment changes. Therefore, even a very small deformation of the portal column 14 due to the temperature fluctuation greatly affects the positioning accuracy.

  In this embodiment, in order to keep the portal column 14 in a stable thermal state, the main body of the portal column 14 serves as a cooling water reservoir for storing the temperature-controlled cooling water. The following cooling water storage space is formed inside.

Here, FIG. 2 is a diagram showing the front of the portal column 14, and FIG. 3 is a diagram showing a cross section of the portal column 14.
The portal column 14 according to this embodiment is a casting in which the columns 15 and 15 and the cross rail 16 are integrated. The inside of the portal column 14 is hollow, and is divided into a plurality of sections, and a cooling water storage space is formed there. In the case of this embodiment, the inside of the portal column 14 is symmetrically provided with seven first to seventh cooling water storage compartments 36a to 36g by using inclined partition walls 30, 31, 32, 33 for securing rigidity. It is divided into.

  In the lower portions of the left and right columns 15, water intake ports 38a and 38b communicating with the first cooling water storage section 36a and the seventh cooling water storage section 36g are formed. As will be described later, the water intake ports 38a and 38b also serve as a drain port through which cooling water is extracted from the column 15, so that the water intake ports 38a and 38b are preferably provided as low as possible below the column 15.

  On the other hand, a drain hole 40 communicating with the fourth cooling water storage compartment 36d is formed at a high position in the center of the cross rail 16. The position of the drain hole 40 is preferably set as high as possible relative to the water intake ports 38a and 38b, and provided near the top surface of the cross rail 16.

  The first cooling water storage section 36 a and the second cooling water storage section 36 b communicate with each other through a cast hole 41 of the inclined partition wall 30, and the second cooling water storage section 36 b and the third cooling water storage section 36 c are connected to the inclined partition wall 31. It communicates through the cast hole 42. The third cooling water storage section 36 c and the fourth cooling water storage section 36 d are communicated with each other through a cast hole 43 of the inclined partition wall 30. Similarly, the fourth cooling water storage section 36d and the fifth cooling water storage section 36e communicate with each other through the cast hole 44 of the inclined partition wall 32. The fifth cooling water storage section 36e and the sixth cooling water storage section 36f communicate with each other through the cast hole 45 of the inclined partition wall 33, and the sixth cooling water storage section 36f and the seventh cooling water storage section 36g are provided on the inclined partition wall 32. It communicates through the cast hole 46.

  In the present embodiment, air vent holes 49 are provided so as to communicate with the third to fifth cooling water storage compartments 36c, 36d, and 36e partitioned inside the cross rail 16, respectively. The air vent hole 49 is located higher than the drain hole 40.

  As shown in FIG. 2, cast holes 47 and 48 are formed on the front surface of the portal column 14 because of the necessity for casting. These cast holes 47 and 48 are closed by a cover. .

  Next, FIG. 4 is a diagram showing a cooling water system in the portal precision machine tool. In FIG. 4, reference numeral 50 is a cooling water temperature adjusting device that controls the temperature of the cooling water to a desired constant temperature. The cooling water temperature control device 50 and the water intakes 38 a and 38 b of the portal column 14 are connected by a pipe 51. The pipe 51 is provided with a backflow prevention valve 52 for preventing a backflow of cooling water from the portal column 14 to the cooling water temperature adjusting device 50. In this embodiment, the water intake ports 38 a and 38 b also serve as a drain port for extracting cooling water from the inside of the portal column 14, and a drain pipe 53 is branched from the pipe 51. The drain pipe 53 is provided with a drain valve 58. When the cooling water is supplied from the cooling water temperature adjusting device 50 to the portal column 14, the backflow prevention valve 52 is opened and the drain valve 58 is closed. When the cooling water is drained from the portal column 14, the backflow prevention valve 52 is closed and the drain valve 58 is closed, and these valves constitute means for switching the pipeline.

  On the other hand, the cooling water recovery pipe 54 extending from the drain hole 40 provided in the upper part of the portal column 14 extends to the cooling water tank 55. The cooling water tank 55 is a tank that stores cooling water that has overflowed from the portal column 14. In this embodiment, the cooling water tank 55 is provided with level sensors 56a and 56b for monitoring the amount of cooling water. The level sensor 56a detects the lower limit of the water surface level, and the level sensor 56b detects the upper limit of the water surface level. The cooling water tank 55 and the cooling water temperature adjusting device 50 are connected by a return pipe 57, and the cooling water accumulated in the cooling water tank 55 is returned to the cooling water temperature adjusting device 50 at a predetermined flow rate. .

  The cooling water may be water, but preferably, water-soluble cooling liquid for machine tool temperature control such as Precise Fluid 2001 (trade name), manufactured by JX Nippon Oil & Energy Corporation is dissolved in water. It is preferable to use the above as cooling water. By using such a cooling liquid, the heat exchange performance of the cooling water is enhanced, and the anticorrosion effect is also enhanced.

The precision machine tool according to the present embodiment is configured as described above. Next, its operation and effect will be described.
In FIG. 4, the cooling water sent from the cooling water temperature adjusting device 50 through the pipe 51 is led into the portal column 14 from the intake ports 38a and 38b at the lower part of the portal column 14, and the first to seventh cooling waters are introduced. Each of the water storage compartments 36a to 36g is filled with cooling water. Then, the cooling water overflowing from the uppermost cooling water storage section 36 d through the drain hole 40 is recovered in the cooling water tank 55 through the cooling water recovery pipe 54. The cooling water accumulated in the cooling water tank 55 is cooled to a constant temperature by the cooling water temperature adjusting device 50 and then sent to the portal column 14 again.

  In the present embodiment, in order to fill the interior of the portal column 14 with cooling water controlled at a constant temperature, an air vent hole 49 is provided in the upper portion of the portal column 14 in addition to the drain hole 40. Thereby, as the water level of the cooling water rises inside the column, air is discharged from the air vent hole 49, so that the gate column 14 has a height up to a height where the drain hole 40 is located without receiving air pressure. The inside can be filled with cooling water. In addition, since the drain hole 40 is disposed at the upper part of the portal column 14, the cooling water can be stored in the entire interior of the portal column 14.

  In this way, according to the present embodiment, the cooling water maintained at a predetermined temperature in the first cooling water storage compartment 36a to the seventh cooling water storage compartment 36g that is partitioned in the entire interior of the portal column 14. In other words, the gate column 14 itself can be used as a temperature-controlled cooling water tank.

  In addition, convection occurs in the cooling water inside the portal column 14, and the heated cooling water rises and is discharged from the drain hole 40 to the cooling tank 55. During this time, cooling water continues to be supplied from the cooling water temperature control device 50 to the inside of the gate column 14. Thus, by providing the drain hole 40 in the upper part of the column, the cooling effect is suppressed by suppressing the temperature rise of the cooling water inside the portal column 14, and the temperature of the cooling water is managed uniformly regardless of the environmental temperature change. It becomes possible to do.

  Further, in the present embodiment, the cooling water overflowed from the drain hole 40 is once collected in the cooling water tank 55 so that a constant amount of cooling water is always stored in the portal column 14, and this cooling water A circulation system is configured so as to be sent from the tank 55 to the cooling water temperature adjusting device 50. If the overflowed cooling water is stored in the cooling tank 55, a constant amount of cooling water can always be stored in the portal column 14. In this embodiment, the cooling water level is monitored by the level sensors 56 a and 56 b that detect the cooling water level in the cooling field tank 55. When the level of the cooling water is lower than the lower limit, the level sensor 56b detects it. Conversely, when the level of the cooling water exceeds the upper limit, it is detected by the level sensor 56a. Can be prevented from overflowing.

  As described above, according to this embodiment, the cutting direction (Z axis) of the tool is in the vertical direction, the distance between the workpiece and the guide surface 18 of the cross rail 16 is large, and the gate is susceptible to temperature fluctuations. Even in a portal precision machine tool having a column 14, the interior of the column 14 is always filled with cooling water whose temperature is controlled, and cooling water introduced from water intakes 38 a and 38 b at the bottom of the column is provided at the top of the column. Since the cooling effect is enhanced by overflowing from the drain hole 40, the entire thermal state of the portal column 14 can be kept constant over a long period of time, not a partial area, and a highly accurate mirror surface for the workpiece This contributes to the realization of nanometer-order ultra-precise machining such as the above-mentioned machining.

  By the way, when the machine tool is moved or repaired, it is necessary to drain the cooling water stored in the portal column 14. In that case, the cooling water can be extracted from the portal column 14 as follows.

  In FIG. 4, when the backflow prevention valve 52 is closed so that the cooling does not flow back to the cooling water temperature adjusting device 50, when the drain valve 57 is opened, the cooling water accumulated in the portal column 14 is It is discharged through the drain pipe 53.

  As described above, according to the present embodiment, by switching the backflow prevention valve 52 and the drain valve 57, the cooling water can be discharged from the cooling water intake 38, so that the intake 38 can also serve as the drain. It becomes possible. For this reason, it is not necessary to make a hole in the portal column 14 in order to provide a drain port for draining the cooling water, and a structure for allowing the cooling water to be stored in the portal column 14 is simplified. Therefore, the man-hour for this can be reduced.

Second embodiment
Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is an embodiment in which the present invention is applied to a horizontal precision machine tool. The same components as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 5, reference numeral 84 indicates a bed. A saddle 85 is provided on the bed 84 so as to be movable in the front-rear direction. A table 86 is installed on the saddle 85 so as to be movable in the left-right direction. A spindle head 88 is held on a column 87 installed on the bed 84 so as to be movable up and down, and a spindle 90 is supported horizontally on the spindle head 88.

  In the horizontal precision machine tool of this embodiment, a plurality of cooling water storage sections 92 are partitioned inside by utilizing the fact that the column 87 is a casting, and the cooling water temperature is passed through a water intake 91 provided at the lower part of the column 87. Cooling water sent from the adjusting device 50 is introduced. As in the first embodiment, the cooling water overflowed from the drain hole 93 is once collected and stored in the cooling water tank 55 so that a constant amount of cooling water is always stored in the column 85. In addition, the circulation system is configured so as to be sent from the cooling water tank 55 to the cooling water temperature adjusting device 50. Apart from the drain hole 93, an air vent hole 94 is provided at a higher position.

  Similarly to the first embodiment, the water intake port 91 also serves as a drain port for extracting cooling water from the column 87, and a drain pipe 53 branches from the pipe 51. The drain pipe 53 is provided with a drain valve 58.

  Thus, since the air vent hole 94 is provided separately from the drain hole 93, the entire interior of the column 87 can be filled with the cooling water to the height at which the drain hole 93 is present without being blocked by receiving air pressure. it can. Moreover, since the cooling effect is enhanced by overflowing the cooling water from the drain hole 93 provided in the upper part of the column 87, it is possible to keep the entire thermal state of the column 87 constant for a long time, not partially. Therefore, it contributes to the realization of time-consuming ultra-precision machining such as high-precision mirror machining of workpieces.

  By the way, when the cooling water stored in the column 87 is drained when the machine tool is moved or repaired, the cooling water can be drained as follows.

  When the backflow prevention valve 52 is closed so that the cooling does not flow back to the cooling water temperature adjusting device 50 and the drain valve 58 is opened, the cooling water accumulated in the column 87 is discharged through the drain pipe 53. The

  Thus, according to this embodiment, since the cooling water can be discharged from the cooling water intake 91 by switching the backflow prevention valve 52 and the drain valve 58, the intake 91 can also serve as the drain. It becomes possible.

  In the second embodiment, an example is shown in which a column of a horizontal precision machine tool is configured as a tank. However, a spindle head is similarly applied to a vertical precision machine tool column in which the spindle is supported vertically. It can also be configured as a tank.

  DESCRIPTION OF SYMBOLS 10 ... Bed, 11 ... Guide surface, 12 ... Table, 14 ... Portal column, 15 ... Column, 16 ... Cross rail, 17 ... Saddle, 18 ... Guide surface, 20 ... Spindle head, 22 ... Spindle, 30, 31, 32, 33 ... inclined partition walls, 36a-36g ... cooling water storage compartment, 38a, 38b ... intake port, 40 ... drain port, 50 ... cooling water temperature control device,

Claims (6)

In a precision machine tool in which a spindle head that is vertically movable is provided on a column that is erected on a bed, and a temperature-controlled cooling water storage space is formed inside the column,
The lower part of the column has a water intake port through which cooling water is introduced into the water storage space, and the upper part of the column has a first drain port through which the cooling water is led to the outside. A precision machine tool that also serves as a second drain port that drains the entire amount of cooling water from the inside of the column. A cooling water tank for collecting cooling water overflowed from the water intake;
A cooling water temperature control device that controls the temperature of the cooling water taken from the cooling water tank and sends out the temperature-controlled cooling water to the water intake, further comprising a cooling water circulation system,
A drain pipe is branched from a pipe connecting the cooling water temperature control device and the water intake, a flow path communicating the cooling water temperature control device and the water intake, and a flow path connecting the drain pipe and the water intake. The precision machine tool according to claim 1, further comprising a switching valve mechanism for switching to one of the flow paths.   2. The precision machine tool according to claim 1, wherein an air vent hole for discharging the air in the column is provided at a position higher than the drain port.   In the precision machine tool, a cross rail is horizontally mounted on columns erected on both the left and right sides of the bed, and a saddle is provided on the cross rail so as to be movable in the left-right direction. The precision machine tool according to claim 1, wherein the precision machine tool is a portal precision machine tool having a portal column provided with a movable spindle head.   The precision machine tool according to claim 1, wherein the portal column is a casting in which the column and the cross rail are integrally structured.   2. The precision machine tool according to claim 1, wherein the precision machine tool is a vertical or horizontal precision machine tool in which a spindle head that is movable in a vertical direction is provided on one column that is erected on a bed. Precision machine tool.

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