JPH0749181B2 - Attitude control device for machine tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is based on a change in the position of a tool due to a temperature rise of a tool driving part or the like in a machine tool such as a machining center or a machining reaction force of the tool. The present invention relates to a posture control device for a machine tool that can prevent deterioration of machining accuracy and realize more precise machining.

(Prior Art) Conventionally, in a machine tool such as a machining center, heat generated by a drive motor of a tool and its reduction mechanism is transmitted to a head portion and a column portion supporting the head portion during machining of a workpiece.
Each of these heat-transferred parts thermally expands according to the rising temperature. Further, a machining reaction force is generated in the tool during machining of the work, and a minute elastic deformation is generated in the head portion and the column portion supporting the tool according to the reaction force. When such thermal expansion or elastic deformation occurs, the position of the tool changes minutely and the processing accuracy decreases. FIG. 8 is an explanatory view schematically showing the situation. In the figure, the heat generated by the tool driving motor 3 installed in the tool 1 and the head portion 2 propagates from the head portion 2 to the column portion 4, and a temperature gradient is generated in the column portion 4 so that the right side expands more and Warp to the left. As a result, the tool 1 is deviated from the normal level L ₀ to the position of the level L ₁ , and the processing accuracy is adversely affected.

As a countermeasure against these problems, conventionally, cooling oil or cooling water is circulated in the head portion 2 to which the tool 1 is attached to cool the drive motor 3 and its speed reduction mechanism portion, which are causes of heat generation, and influence by thermal expansion. Trying to resolve.

Further, as another solution, the coordinates of the head unit 2 may be corrected by NC control according to the degree of heat generation. Further, a counter heater 5 is provided on a part of the left rear surface of the column portion 4.
It has been attempted to eliminate the warp by installing a column and heating according to the heat transfer to the column section 4 to remove the temperature gradient.

(Problems to be solved by the invention) However, it is difficult for these solutions to accurately detect the deformation caused in the tool due to heat generation during operation, and the detected amount of deformation is constantly changed depending on the operating condition. Since it fluctuates, the responsiveness is inferior, and it is impossible to always perform optimum correction.

The present invention has been made to solve the above problems,
The purpose is to fundamentally correct minute deformation caused by thermal expansion and elasticity change, which is a problem during position control in various industrial machines such as machine tools, and to make it more precise. An object of the present invention is to provide a posture control device for a machine tool that enables position control.

(Means for Solving the Problems) In order to achieve the above object, a first aspect of the present invention is configured such that a head portion that grips and drives a tool is attached to and supported by a fixed pedestal so as to face each other in the circumferential direction. One or more pairs are arranged, and the column part thermal actuator that heats or cools the column part wall surface to generate thermal deformation, and the column part thermal actuator is installed on the column part wall surface,
A deformation sensor that detects deformation of the wall surface of the column that occurs due to temperature change, processing reaction force of the tool, and based on the detection value of the deformation sensor, expand and contract the column to hold the preset tool position. And a controller for outputting a thermal actuator control signal.

A second aspect of the invention is one or more pairs of circumferentially opposed hollow column portions that mount and support a head portion that grips and drives a tool on a fixed pedestal, and heats or cools the wall surface of the column portion to cause thermal deformation. A thermal actuator for the column, a thermal actuator for the column, which is installed on the wall of the head, detects deformation of the wall of the head caused by temperature changes, processing reaction force of the tool, etc., and a thermal actuator for the column are attached. Based on the deformation sensor installed on the wall surface of the column and detecting the deformation of the wall surface of the column that occurs due to temperature change, processing reaction force of the tool, etc., based on the detection value of each deformation sensor,
And a control unit for outputting a thermal actuator control signal for expanding and contracting the column unit so as to hold a preset tool position.

A third aspect of the present invention is to provide a head thermal actuator in which one or more pairs of heads are arranged facing each other in the circumferential direction of a head that grips and drives a tool, and heats or cools the wall surface of the head to generate thermal deformation. The column-shaped thermal actuator and the head-shaped thermal actuator, in which one or more pairs are arranged so as to face each other in the circumferential direction of the hollow column section that attaches and supports the column section to the fixed pedestal, and heats or cools the wall surface of the column section to generate deformation It is installed on the wall surface of the head part where the actuator is attached, and it is installed on the wall surface of the column part where the deformation sensor that detects the deformation of the wall surface of the head part caused by temperature change, tool reaction force, etc. and the thermal actuator for the column part are installed. Based on the deformation sensor that detects the deformation of the wall surface of the column that occurs due to temperature change, tool reaction force, etc., and the detection value of each deformation sensor. Characterized by comprising a control unit for outputting a thermal actuator control signal to the column portion and the head portion is stretchable respectively to hold the tool position set in advance.

(Operation) In the first aspect of the invention, when deformation occurs on the wall surface of the column portion due to temperature change, processing reaction force of the tool, etc., the deformation is detected by the deformation sensor installed on the wall surface of the column portion. Next, a control signal for the column actuator is output from the controller according to the detected deformation value, and the column wall surface is heated or cooled by the column actuator. As a result, the wall surface of the column portion is stretched and controlled, and the tool is held at a predetermined position.

In the second aspect, when deformation occurs on the wall surfaces of the head portion and the column portion due to temperature change, processing reaction force of the tool, etc., the deformation is detected by the deformation sensor installed on the wall surfaces of the head portion and the column portion. Then, a control signal for the column actuator is output from the controller according to the detected deformation amount, and the column wall surface is heated or cooled by the column actuator. As a result, the wall surface of the column portion is stretched and controlled, and the tool is held at a predetermined position.

In the third aspect of the invention, when deformation occurs in the head and column wall surfaces due to temperature change, processing reaction force of the tool, etc., the deformation is detected by the deformation sensor installed on the head and column wall surfaces. Then, a control signal of each thermal actuator is output from the control unit according to the detected deformation amount, and the wall surface of the head unit and the column unit is heated or cooled by each thermal actuator. As a result, the wall surfaces of the head and column parts are controlled to expand and contract,
The tool is held in place.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of an embodiment in which the first and second inventions are applied to a machining center, and FIG. 2 is a sectional view taken along the line II-II of FIG.

In the figure, the column portion 14 fixed on the base 6 is formed hollow, and the balance weight 7 of the head portion 12 is suspended inside. The head portion 12 is supported by a guide portion formed on the front surface of the column portion 14 so as to be vertically movable, and the servo motor 1 mounted on the upper portion of the column portion 14
5 and the ball screw 16 control the vertical position. Further, a tool attachment portion 17 is provided at the tip of the lower surface of the head portion 12 so that the tool 11 can be detachably held according to the processing work. The tool 11 is driven by a motor 13 installed above the head portion 12 via a reduction mechanism (not shown).

The work W is fixed on the table 18, and is processed by the tool 11 while the drive mechanism 8 moves the table 18 in the X and Y directions.

Further, the column portion 14 is formed in a hollow prismatic shape, and ribs are formed at regular intervals in the inner circumferential direction. The column portion 14 is formed by the lower base 6 among the division portions divided by the ribs.
Thermal actuators 21-28, 31-38 on the inner surface of the stair compartment
Is installed. This thermal actuator is composed of a thermal semiconductor element capable of electronic cooling and heating, and the contact surface with the wall surface can be changed to either heating or cooling by changing the current direction. Further, in the circumferential direction in the member of the column portion 14 at the positions where the boundaries of the sections where the thermal actuators 21 to 28 and 31 to 38 are installed and the ribs above and below the partitions are formed in the circumferential direction, Oil is formed and circulated at a predetermined temperature to provide thermal insulation between the compartments. Further, at the end portions of both side surfaces of the column portion 14 corresponding to the upper and lower sides of FIG.
S4 is attached, and the amount of deformation due to expansion and contraction of the column portion 14 is detected. The detected deformation amount is input to the control unit (not shown), and then the current directions to be supplied to the 16 thermal actuators 21 to 28 and 31 to 38 arranged in the upper and lower stages are individually determined according to the deformation amount. Control. In the case of the second invention, the deformation amount detected by the deformation sensors S5 to S10 in the head portion 12 in the embodiment of the third invention which will be described later is also input to the control unit, and the deformation amount is also taken into consideration to generate heat. Actuator 21-2
Controls the operation of 8,31 to 38. In this way, the column section
When the wall surface on which the thermal actuator 14 is installed is heated or cooled, the amount of expansion and contraction is adjusted appropriately according to the temperature, and the heat generated by the motor 13 and the elastic deformation due to the processing reaction force of the tool 11 are combined, The change in the position generated in the tool 11 is corrected. As a result, the tool 11 is precisely held in its original position, and can be machined with an accuracy higher than before.

3 is an external view of an essential part of an embodiment in which the third invention is applied to a machining center, FIG. 4 is a transverse sectional view of FIG. 3, and FIG. 5 is a V- of FIG. It is sectional drawing on the V line.

The part of the third embodiment different from the first embodiment is that a thermal actuator and a heat insulating part are installed also in the head part 12, and the thermal actuators installed in the column part 14 and the head part 12 are electrically heated. It is composed of a combination of oil jacket. Specifically, similar to the embodiment of FIG. 1, the thermal actuators 41a to 41c for cooling are provided on the outer peripheral surface of the partition section below the lower base 6, which is partitioned by the ribs formed at regular intervals in the column section 14. Similarly, the thermal actuators 51a to 58a for cooling are installed on the upper side of the 48a. Each of these stages of thermal actuators 41a-48
a, 51a to 58a are formed by an oil jacket, and low-temperature oil supplied from an oil cooler (not shown) is circulated to allow thermal actuators 41a to 48a and 51a to 58a.
Are cooled to cool the wall surface of the column portion 14 that comes into contact with them. In addition, these thermal actuators 41a to 48a, 51a
The thermal actuators 41b to 48b and 51b to 58b for heating are installed on the inner peripheral surface of the column portion 14 in the lower and upper stages, respectively, as opposed to the to 58a. These thermal actuators 41b-48b, 51b
~ 58b is formed by a sheet-like electric heater, by supplying an electric current, thermal actuators 41b ~ 48b, 51b ~.
58b heats up to a high temperature and heats the wall surface of the column portion 14 that comes into contact.

During operation, the thermal actuators 41a, 41b to 58a, 58b for heating or cooling, which make up a pair respectively, operate either one of the inner and outer surfaces to cool or heat the attached block. Further, at the end portions on both side surfaces of the column portion 14, the fourth
As shown in the figure, deformation sensors S1 to S4 are attached to detect the amount of deformation of the column portion 14 in the axial direction.

Further, the head portion 12 is formed of a hollow frame, and the thermal actuators 62 for cooling are provided on the outer peripheral portions of the upper and lower two stages of the frame.
a to 67a and 72a to 77a are installed, respectively, and at the same time, thermal actuators 61b for heating are provided in two upper and lower stages on the four inner surfaces of the frame.
~ 68b, 71b ~ 78b are installed respectively. Further, since the head portion 12 and the column portion 14 are thermally insulated inside the frame member from the column portion 14, a flow path for circulating the cooling oil is provided.
69 are formed at equal intervals in the horizontal direction.

Thermal actuators 62a-67a, 72a-77a for cooling these
Is also formed of an oil jacket like the column portion 14, and is also used for heating thermal actuators 61b to 68b and 71b to 7b.
Similarly, 8b is also formed by a planar electric heater, and cools or heats each block of the head unit 12 in contact with each other by supplying low temperature oil or electric current, respectively. Further, the temperature compensation is composed of strain gauges horizontally arranged at the center positions of the thermal actuators 66a, 67a, 76a, 77a arranged on the side surfaces of the head portion 12 shown in FIG. Deformation sensors S5 to S7 are attached, and deformation sensors S8 to S7
S10 is attached and the amount of deformation generated in the head portion 12 is detected. The deformation amount detected by the deformation sensors S5 to S10 is input to a controller (not shown), and then the thermal actuators 62a to 67a, 72a to 77a, 61b to 68b, 71b to 78b are input according to the deformation amount.
By controlling the heating or cooling of the head unit 12 to heat or cool each surface of the head unit 12 on which the thermal actuator is installed for each block, the expansion and contraction amount can be adjusted appropriately to correct the deformation generated at the tip of the tool 11. It is possible to perform processing while maintaining the original position of the tool 11.

FIG. 6 shows a typical example of the control mode in which the operations of the respective thermal actuators of the column portion 14 are combined in the embodiment of the first or second invention described above. In the figure,
The actuator labeled "C" is cooling, and the actuator labeled "H" is heating.

FIG. A shows a mode in which both the upper and lower stages are cooled so that the right side on the head side is displayed as "C" and heated as shown on the left side as "C", and the column part 14 is inclined to the right by the angle θ ₁ . Indicates that.

FIG. B shows a mode in which the right side of the head portion side is heated and the left side is cooled in both upper and lower stages, and shows that the column portion 14 is inclined to the left side by an angle θ ₂ .

FIG. 7C shows a mode in which the right side of the upper stage is heated, the left side is cooled, the right side of the lower stage is cooled, and the left side is heated, and the column portion 14 moves a distance l ₁ substantially parallel to the right side.

FIG. D shows a mode in which the right side of the upper stage is cooled, the left side is heated, the right side of the lower stage is heated, and the left side is cooled, and the column portion 14 moves to the left side in a substantially parallel distance l ₂ .

The control modes of the above four examples are examples in which the heating and cooling of the corresponding thermal actuators are the same between the front side and the back side of the drawing. In addition to these combination modes, since the number of thermal actuators installed in the column unit 14 is 16, the number of combinations of heating and cooling of each thermal actuator is large, and the deformation values of the displacement sensors S1 to S4, or the deformation sensor S1. Fine control can be performed according to the detection values of ~ S4 and the deformation sensors S5 ~ S10.

FIG. 7 shows a typical example of the control mode in which the operation of the thermal actuator in the head portion 12 similarly mounted in the embodiment of the third invention is combined.

FIG. A shows a mode in which both upper side thermal actuators of the head portion 12 are cooled and both lower side heating actuators are heated, and the head portion 12 is inclined counterclockwise by the angle θ ₃ .

FIG. B shows a mode in which both the upper thermal actuators are heated and the lower thermal actuators are both cooled, and the head portion 12 is inclined clockwise by an angle θ ₄ .

FIG. 7C shows a mode in which the upper left side and the lower right side are cooled and the upper right side and the lower left side are heated, and the lower end of the tool mounting portion 17 moves upward in a substantially parallel distance l ₃ .

FIG. D shows a mode in which the upper left side and the lower right side are heated and the upper right side and the lower left side are cooled, and the lower end of the tool mounting portion 17 moves downwardly in a substantially parallel distance l ₄ .

The control modes of the above four examples are examples in which the heating and cooling of the corresponding thermal actuators are the same between the front side and the back side of the drawing. In addition to these combination modes, since the number of thermal actuators installed in the head unit 12 is 16, there are many combinations of heating and cooling for each thermal actuator, and fine control is performed according to the detection values of the deformation sensors S5 to S10. Will be possible.

In the machining center shown in the third embodiment of the present invention, the head 12 is thermally deformed by the heat generated by the driving motor 13 and the speed reduction mechanism thereof, and the work W is machined. Irregular elastic deformation due to processing reaction force generated in 11 is also comprehensively detected by sensors S5 to S10, heating / cooling of each thermal actuator is controlled according to these deformation amounts, and deformation is corrected in real time. -It becomes possible to proceed with the processing of the work W while controlling.

Further, a flow path 69 for circulating the cooling oil is installed on the column part 14 side of the head part 12 so that the cooling oil having a temperature slightly lower than the ambient temperature is constantly supplied. Thereby, the head portion 12
Is suppressed from being transmitted to the column portion 14, and thermal expansion and warpage due to heat transfer from the head portion 12 in the column portion 14 are prevented.

Further, in the case where the deformation that cannot be corrected by the control of only the head unit 12, the deformation of the entire head unit 12, and the deformation of the column unit 14 itself, the column unit 14 itself also similarly performs the sensor.
The control for deformation correction is performed according to the detection values of S1 to S4 and the sensors S5 to S10. At this time, the head unit 12
The position control of the tool is performed by combining the deformation control of the column part 14 and the column part 14, and more accurate machining can be realized.

According to the experiment of the applicant, the machining shown in FIG.
In the embodiment of the center, as a result of controlling the operation of each thermal actuator under the conditions of an ambient temperature of 35 ° C., a heating temperature of the thermal actuator of 45 ° C., and a cooling temperature of 25 ° C., the tip position of the tool 11 is within a range of about 30 μm. It was confirmed that control was possible.

In each of the above-described embodiments, the operation of each thermal actuator is only heating or cooling, but depending on the position of the thermal actuator, it may be in an intermediate standing state in which neither heating nor cooling is performed, or the set temperature of the thermal actuator is set to the heating unit. It is possible not only to set two points of the high temperature and the cooling temperature of the cooling unit but also to set a continuous intermediate temperature for more highly accurate control.

Further, in the embodiment, the positional deviation caused mainly by the thermal deformation due to the heat generation of the tool motor 30 and the elastic deformation due to the processing reaction force is
Although the control for correction by each thermal actuator has been described, the position control of the tool can be performed more precisely by positively controlling the operation of each thermal actuator during processing as described above. For example, when processing a die or the like at a machining center, by using this attitude control device, it is possible to realize ultra-precision processing on the order of microns, which has heretofore been impossible.

Furthermore, in each of the above embodiments, the column portion 14 and the head portion 12
Although four thermal actuators are installed on each surface with two in two stages, it is also possible to provide one surface with two stages, and depending on the position of the surface to be installed, The thermal actuator can be controlled by arbitrarily combining the number of installed stages and the number of installed thermal actuators.

Furthermore, it is also possible to arrange a temperature sensor in each part of the main structural frame that constitutes the machine tool and to control each thermal actuator in consideration of thermal deformation based on the detected overall temperature distribution. In that case, the accuracy is improved as compared with the case where each thermal actuator and the sensor attached thereto are individually controlled.

Further, these inventions in which the thermal actuator is installed on the wall surface of the hollow structure to cause the thermal deformation to control the posture of the structure can be applied to the structural portion of various machine tools other than the machining center, and similarly. It is possible to further improve the processing accuracy of various machine tools applied.

(Effects of the Invention) As described above, according to the first aspect of the invention, even when deformation occurs on the wall surface of the column part of the machine tool due to temperature change, processing reaction force of the tool, or the like, the column part responds to the deformation. The wall surface is heated or cooled by the column actuator and the column portion is expanded and contracted. As a result, the tool is held at a predetermined position, and the machining accuracy is significantly improved as compared with the conventional machine tool.

Further, according to the second aspect of the invention, even when the head portion and the column portion wall surface of the machine tool are deformed due to a temperature change, a processing reaction force of the tool, or the like, the column portion wall surface is used for the column portion according to the deformation. The thermal actuator heats or cools the column to control expansion and contraction, and the tool is held at a predetermined position. As a result, the machining accuracy is remarkably improved as compared with the conventional machine tool.

Further, according to the third aspect of the invention, even if the head and column wall surfaces of the machine tool are deformed due to temperature change, tool reaction force, etc., the head and column wall surfaces are deformed according to the deformation. Each of the thermal actuators is heated or cooled to control the expansion and contraction of the head portion and the column portion, and the tool is held at a predetermined position. As a result, the machining accuracy is remarkably improved as compared with the conventional machine tool.

Furthermore, in the first, second, and third inventions, since the thermal actuator installed on the wall surface of the column portion or the like can be used to perform micro-deformation in advance at the tool position for machining,
It enables ultra-precision machining that cannot be realized with conventional machine tools.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment in which the first and second inventions are applied to a machining center, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is an embodiment of the third invention. An external view of the main part of the example, FIG. 4 is a cross-sectional view of FIG. 3, FIG. 5 is a cross-sectional view taken along the line VV of FIG. 4, and FIG. FIG. 7 is an explanatory diagram showing an example of a control mode of the head portion, and FIG. 8 is an explanatory diagram of occurrence of thermal deformation in the conventional example. 12 …… Head part, 13 …… Motor, 14 …… Column part, 17…
… Tool mounting part, 19 …… flow path, 29 …… flow path, 39 …… flow path, 69 …… flow path 21 to 28 …… thermal actuator 31 to 38 …… thermal actuator 41a to 48a …… for cooling Thermal actuators 41b to 48b ...... Heating thermal actuators 51a to 58a ...... Cooling thermal actuators 51b to 58b ...... Heating thermal actuators 61b to 68b ...... Heating thermal actuators 62a to 67a ...... Cooling Thermal actuators 71b to 78b ...... Heating thermal actuators 72a to 77a ...... Cooling thermal actuators S1 to S10 ...... Deformation sensor with temperature compensation

Claims (3)

[Claims] 1. One or more pairs of heads for holding and driving a tool are arranged facing each other in the circumferential direction of a hollow column part for mounting and supporting the head part on a fixed pedestal, and the wall surface of the column part is heated or cooled for thermal deformation. The thermal actuator for the column to be generated, the deformation sensor installed on the wall of the column where the thermal actuator for the column is attached, and the deformation sensor that detects the deformation of the wall of the column caused by temperature change, processing reaction force of the tool, etc. A posture control device for a machine tool, comprising: a control unit that outputs a thermal actuator control signal for expanding and contracting the column unit so as to hold a preset tool position based on a detection value of the sensor. . 2. One or more pairs of heads for holding and driving a tool are attached to a fixed pedestal so as to face each other in the circumferential direction of a hollow column part, and the wall surface of the column part is heated or cooled to cause thermal deformation. The thermal actuator for the column that is generated, the deformation sensor that is installed on the wall surface of the head, and detects the deformation of the wall surface of the head that occurs due to temperature changes, processing reaction force of the tool, etc. A deformation sensor that is installed on the wall surface of the part to detect deformation of the wall surface of the column part that occurs due to temperature change, processing reaction force of the tool, etc., and holds the preset tool position based on the detection value of each deformation sensor. An attitude control device for a machine tool, comprising: a control unit that outputs a thermal actuator control signal that causes the column unit to expand and contract. 3. A thermal actuator for a head portion, wherein one or more pairs of head portions are arranged facing each other in the circumferential direction of the head portion for gripping and driving a tool, and heat or cool the wall surface of the head portion to generate thermal deformation, and a head portion. One or more pairs of column-shaped thermal actuators, which are arranged to face each other in the circumferential direction of the hollow column that mounts and supports the column on the fixed pedestal, heats or cools the wall surface of the column to generate thermal deformation, and a thermal actuator for the head. Installed on the wall surface of the head part where the actuator is installed, installed on the wall surface of the column part where the deformation sensor that detects the deformation of the wall surface of the head part caused by temperature change, tool reaction force, etc. and the thermal actuator for the column part are installed Based on the deformation sensor that detects the deformation of the wall surface of the column that occurs due to temperature change, tool reaction force, etc., and the detection value of each deformation sensor. And a control unit that outputs a thermal actuator control signal for expanding and contracting the column unit and the head unit so as to hold a preset tool position, and a posture control device for a machine tool.