KR20100102198A

KR20100102198A - Machine tool

Info

Publication number: KR20100102198A
Application number: KR1020107017372A
Authority: KR
Inventors: 히로유키 도마루; 게이지 미즈타
Original assignee: 미츠비시 쥬고교 가부시키가이샤
Priority date: 2008-02-07
Filing date: 2009-01-20
Publication date: 2010-09-20
Also published as: JP2009184077A; CN101939134A; KR101198058B1; JP5001870B2; TW200938329A; CN101939134B; WO2009098931A1; TWI381902B

Abstract

The present invention relates to a machine tool which can be prevented from lowering the machining accuracy even when the column is deformed by the movement of the main axis in the respective axial direction. The machine tool 1 for processing the workpiece W by moving the tool T and the workpiece W relative to each other rotatably supports the main shaft 19 to which the tool T is detachably attached. Saddle 16 for moving, column 14 movably provided and movably supporting saddle 16, and column 14 caused by the movement of at least one of saddle 16 and column 14. And a column deformation detection device 30 for detecting the deformation of the tool, wherein the movement of at least one of the tool T and the work piece W is corrected based on the detection result of the column deformation detection device 30.

Description

Machine tool {MACHINE TOOL}

The present invention relates to a machine tool for processing a workpiece by relatively moving the workpiece and the tool.

In recent years, the demand for high precision machining is increasing. The precision of the machining performed by the machine tool includes the smoothness of the movement of the member, such as the table on which the workpiece is mounted, and the saddle supporting the main shaft, the straightness of the movement of the aforementioned member, the parallelism of the movement with respect to the centerline of the spindle, and It relies heavily on the geometric precision of the machine tool itself, such as squareness. To make this different, the machining precision is determined by the precision of the relative position of the tool and the workpiece during machining.

In addition, in order to process the workpiece with high accuracy, it is necessary for the machine tool itself to maintain high dimensional accuracy. It is important to achieve the above-mentioned objects that, in addition to the positional accuracy of parts of the machine tool, such as tables and saddles, as well as the basis for the movement of the above-described members and the movement of the above-mentioned members, in particular the role of the bed and column It also includes the position precision of the structure. Therefore, these structures which form part of the machine tool are designed to have sufficient rigidity not to be deformed by stress or the like, and are particularly designed not to be affected by vibration.

However, the machine tool is inevitably damaged from the influence of heat generated from the machine tool itself or the influence of ambient temperature. This effect sometimes results in thermal expansion of the structure forming part of the machine tool, and finally deformation of the machine tool. Specifically, when the machine tool is operated, various motors, tools, work pieces, and the like generate heat, and the generated heat is transferred to the structure. The heat transferred in this way causes thermal deformation of the machine tool. In addition, the temperature of the atmosphere in which the machine tool is installed, and the distribution of such temperatures are not uniform from one point to another. Thus, the temperature depends on the part of the structure, ie before, after, left, right, top or bottom. This change in temperature in a single structure leads to thermal deformations such as leaning and warping. Such thermal deformation of the structure may cause the main axis to tilt laterally, resulting in an unsatisfactory level of precision in the machining of the workpiece.

For this reason, various measures have been conventionally taken regarding the precision at the time of processing of a workpiece | work which is influenced by the heat | fever generated by the machine tool itself, and the temperature environment of a machine tool. Machine tools with such countermeasures for solving the above-mentioned problems are disclosed, for example, in patent documents 1 and 2.

Patent Document 1: Japanese Unexamined Patent Publication No. Hei 4-82649

Patent document 2: Unexamined-Japanese-Patent No. 6-39682.

In a machine tool, a plurality of structures enable three-dimensional movement of the main axis supporting the tool along the axis. Movement of the major axis sometimes causes deformation of the structure.

For example, in a machine tool such as a horizontal boring machine, the saddle supporting the main shaft is movably supported on the side wall of the column, and the column is also movable. Thus, especially in large machine tools with long columns and heavy birds, the deformation (tilt) of the column increases as the birds move upwards. This larger strain makes it difficult to maintain the straightness that allows birds to move up and down. Also, as the column moves, the movement of the column affects the straightness of the bed supporting the movement. Thus, the column moves while experiencing angular deviations (pitch, roll, and yaw), resulting in deformation (tilt) of the column. Therefore, an error may occur at the tip position of the main shaft, which may cause an unsatisfactory level of precision in machining the workpiece.

However, the conventional machine tool does not correspond to the above-described deformation resulting from the movement of the main axis in the axial direction, and there is a possibility that machining of the workpiece is performed only at an unsatisfactory level of precision. To achieve higher machining precision, not only thermal deformation of the structure caused by the heat generated by the machine tool itself and the temperature environment of the machine tool, but also deformation of the structure caused by the movement of the main axis in the axial direction is taken into account. I think it should be.

The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a machine tool capable of preventing a decrease in machining accuracy even if the column is deformed due to the movement of the main axis in the axial direction.

The machine tool according to the first invention for solving the above-mentioned problems is a machine tool for processing a workpiece by moving a tool and a workpiece relative to each other.

Saddle rotatably supporting a spindle with a detachably mounted tool,

A column provided movably and movably supporting the saddle,

Column deformation detection means for detecting deformation of said column caused by said saddle and at least one movement of said column, and

And correction means for correcting at least one movement of the tool and the workpiece based on the detection result of the column deformation detection means.

The machine tool according to the second aspect of the present invention for solving the above-mentioned problems is characterized in that the column deformation detecting means includes: a measurement unit suspended vertically downward on the column, and a distance between the column and the measurement unit; Characterized in that it comprises a measuring means.

The machine tool according to the third aspect of the present invention for solving the above-mentioned problems is characterized in that said column deformation detecting means includes damping means for damping vibrations of said portion to be measured.

Machine tool according to the fourth invention for solving the above problems, the column deformation detection means,

A container attached to the column and storing a viscous fluid,

A hanging member which is suspended vertically downwards on the column by a wire,

A first rod-shaped member, the upper end of which is supported by a hanging member via a spherical bushing, the first rod-shaped member including a measurement target,

A second rod-shaped member, the second rod-shaped member having an upper end supported by a hanging member via a spherical bushing, the lower end being immersed in a viscous fluid stored in the container, and

And a distance sensor attached to the column to measure a distance from the distance sensor to the unit under measurement.

The machine tool according to the fifth aspect of the present invention for solving the above-mentioned problems is characterized in that said column deformation detection means is provided inside said column.

Therefore, according to the machine tool of the present invention, even if the column is deformed by the movement of the main axis in the axial direction, the decrease in the machining accuracy is prevented by correcting the movement of at least one of the tool and the workpiece based on the detected amount of deformation of the column. Can be.

1 is a schematic perspective view of a machine tool according to an embodiment of the present invention.
2 is a general configuration diagram illustrating a column deformation detection apparatus.
3 is a cross-sectional view of the column.
4 is a schematic diagram showing that the column is deformed in the X-axis direction.
5 is a schematic diagram showing that the column is deformed in the Z-axis direction.

A machine tool according to an embodiment of the present invention will be described in detail with reference to the drawings below. 1 is a schematic perspective view of a machine tool according to an embodiment of the present invention. 2 is a general configuration diagram illustrating a column deformation detection apparatus. 3 is a cross-sectional view of the column. 4 is a schematic diagram showing that the column is deformed in the X-axis direction. 5 is a schematic diagram showing that the column is deformed in the Z-axis direction. In each of the figures, directions indicated by X, Y, and Z (W) represent orthogonal triaxial directions perpendicular to each other, and in particular, the front and rear directions of the machine tool, the vertical direction of the machine tool, and the width direction of the machine tool. Indicates. Further, the embodiments to be described below apply the machine tool according to the present invention to a large horizontal boring machine.

1 shows a machine tool 1, which is a large horizontal boring machine comprising a bed 11 fixed to the floor. A pair of left and right guide rails 12a and 12b extending in the X-axis direction are formed on the upper surface of the bed 11. The column base 13 is supported by the guide rails 12a and 12b so as to slide in the X-axis direction. A hollow column 14 is erected on the column base 13. Therefore, the column base 13 (column 14) can be moved in the X axis direction by driving column drive means including members such as a column drive motor (not shown) and a column feed screw mechanism (not shown).

A pair of left and right guide rails 15a and 15b extending in the Y axis direction are formed on the front surface of the column 14 (hereinafter referred to as side wall 14b). The saddle 16 is supported by the guide rails 15a and 15b to be able to slide in the Y axis direction. Thus, the saddle 16 can be moved in the Y axis direction by driving the saddle driving means including members such as a not shown saddle drive motor and a not shown saddle feed screw mechanism.

Guides 17 are formed in the saddle 16 to penetrate the saddle 16 in the Z-axis direction. The guide portion 17 is supported so that the ram 18 is slidable in the Z axis direction. Thus, the ram 18 can be moved in the Z-axis direction by driving the ram driving means including members such as a ram drive motor (not shown) and a ram feed screw mechanism (not shown).

The main shaft 19 is supported by the ram 18. The main shaft 19 is thus supported to be rotatable and to be slidable in the W axis direction. A tool T, which performs a substantially predetermined kind of processing, is detachably fixed to the tip of the spindle 19. Accordingly, the main shaft 19 can be rotated around the W axis by driving the main shaft rotating means including a member such as a main shaft rotating motor not shown. Further, the main shaft 19 can be moved in the W-axis direction by driving the main shaft drive means including members such as a main shaft drive motor and a spindle feed screw mechanism, not shown.

On the side of the bed 11 is provided a table bed 21 fixed to a part of the floor. On the upper surface of the table bed 21, a pair of front and rear guide rails 22a and 22b extending in the Z-axis direction are formed. The table base 23 is supported by the guide rails 22a and 22b so as to slide in the Z axis direction. In addition, the upper portion of the table base 23, the rotary table 24 is rotatably supported. The work piece (workpiece) W is detachably attached to the upper surface of the turntable 24. Therefore, the table base 23 (rotation table 24) can be moved in the Z axis direction by driving the table driving means including members such as a table driving motor (not shown) and a table feed screw mechanism (not shown). Further, the rotary table 24 can be rotated around the Y axis by driving a table rotating means including a member such as a table rotating motor not shown.

The machine tool 1 is provided with an NC device (correction means) 50, and controls the entire machine tool 1. The NC device 50 is connected to the above-mentioned driving means, the above-mentioned rotating means, etc., respectively. Therefore, the connected NC apparatus 50 changes the direction and speed which each tool T and the workpiece | work W move. The NC device 50 also adjusts how much each tool T and workpiece W move and rotate. Therefore, the NC device 50 performs positioning control of both the tool T and the workpiece W and also performs indexing control of the workpiece W. FIG. Therefore, the tool T and the work piece W are moved relative to each other, so that a predetermined shape is processed on the work piece W. As shown in FIG.

As shown in Figs. 2 and 3, the column 14 includes an upper wall 14a and side walls 14b, 14c, 14d, 14e, and is formed as a hollow structure. In the column 14 thus formed, the column deformation detection device (column deformation detection means) 30 is supported so as to be suspended vertically from the lower surface of the upper wall 14a.

The column deformation detection device 30 includes two flexible wires 31. Both ends of each wire 31 are attached to the lower surface of the upper wall 14a. A hanging member 33 is suspended on the wire 31 via the passage member 32. A hanging rod (first rod-shaped member and second rod-shaped member) 35 and 36 are attached to the hanging member 33 via a spherical bushing 34. The material and diameter of each wire 31 can be arbitrarily selected. Nevertheless, it may be desirable for the wire 31 to have a rigidity low enough to always hang vertically even when the column 14 is deformed and tilted laterally.

The measuring members 37 and 38 are formed in the axial middle part of the suspension rod 35 and the lower end of the suspension rod 35, respectively. The measurement members 37 are provided with measurement surfaces (measured portions) 37a and 37b, and the measurement members 38 are provided with measurement surfaces (measured portions) 38a and 38b. Each of the measured surfaces 37a and 38a is formed as a plane orthogonal to the X axis direction, while each of the measured surfaces 37b and 38b is formed as a plane orthogonal to the Z axis direction. Also, a weight 39 is provided at the lower end of the suspension rod 36.

The inner surface of the side wall 14b is provided with a pair of upper and lower distance sensors (measurement means) 40a and 40b, and opposes the measured surfaces 37a and 38a, respectively. In addition, upper and lower pairs of distance sensors (measurement means) 41a and 41b are provided on the inner surface of the side wall 14e and face the measurement surfaces 37b and 38b, respectively. The distance sensors 40a, 40b, 41a, 41b are non-contact sensors. The distance sensor 40a always measures the distance from itself to the measurement surface 37a, and the distance sensor 40b always measures the distance from itself to the measurement surface 38a. In addition, the distance sensor 41a always measures the distance from itself to the measurement surface 37b, and the distance sensor 41b always measures the distance from itself to the measurement surface 38b. In addition, the NC device 50 is connected to the distance sensors 40a, 40b, 41a, 41b. The distance (detection result) measured by the distance sensors 40a, 40b, 41a, and 41b is input to the NC device 50.

An oil pan (container) 42 is supported on the inner surface of the side wall 14d via a support member not shown. In the oil pan 42, oil 43, which is a high viscosity fluid, is stored, and a suspension rod 36 is immersed in the oil 43 stored in the oil pan 42. It should be noted that the oil pan 42 and the oil 43 together constitute the damping means.

Therefore, the NC apparatus 50 measures the distance from the distance sensor 40a to the to-be-measured surface 37a measured by the distance sensor 40a, and the distance sensor 40b measured by the distance sensor 40b. X-axis strain amount (X-axis direction tilt amount) of the column 14 is computed from the difference between the distance to the to-be-measured surface 38a. Moreover, the NC apparatus 50 measures the distance from the distance sensor 41a to the to-be-measured surface 37b measured by the distance sensor 41a, and the distance sensor 41b measured by the distance sensor 41b. Z-axis deformation amount (Z-axis direction tilt amount) of the column 14 is calculated from the difference between the distances from the distance to the measurement surface 38b. And the NC apparatus 50 performs position control of the tool T and the workpiece | work W based on the X-axis direction deformation amount and Z-axis direction deformation amount of the column 14 computed in this way. Position control is performed to correct the drive of each drive means so that the workpiece W is processed into a predetermined shape.

Further, even when the suspension rods 35 and 36 vibrate with the hanging member 33 due to disturbance vibration or the like, the vibration of the suspension rod 36 is rapidly attenuated by the oil 43 stored in the oil pan 42. . Therefore, the vibration of the suspension rod 35 is also attenuated in a short time.

When the workpiece W is machined by the machine tool 1, the workpiece W is first mounted on the upper surface of the rotary table 24, and then the table base (H) is moved so that the workpiece W is moved to the machining position. 23) is moved in the Z axis direction. Then, with the tool T being rotated by the main axis 19, the following movements of the member are optionally carried out as necessary: the column 14 is moved in the X axis direction, the saddle 16 is in the Y axis direction Is moved in the Z-axis direction, and the main shaft 19 is moved in the W-axis direction. In addition, the rotary table 24 is rotated as needed to perform the indexing rotation of the workpiece W. In this way, the workpiece W is processed by the tool T.

As described above, while the workpiece W is being processed, the tool T must be moved in at least one of the X axis, Y axis, Z axis, and W axis directions. In particular, deformation of the column 14 is more likely to occur when the tool T is moved in the X-axis direction and / or the Y-axis direction than other cases. As the column 14 is deformed, an error in the position of the tip end of the main shaft 19 tends to occur, and machining accuracy may be reduced.

Specifically, the machine tool 1, denoted as a horizontal boring machine, has a structure in which saddles 16 rotatably supporting the main shaft 19 are supported by the side walls 14b of the column 14. With this structure, as shown in FIG. 4, the movement of the saddle 16 in the Y axis direction is based on the junction of the column base 13 and the column 14 with the column 14 in the X axis direction. Tilt to In particular, when the machine tool 1 is large, the column 14 becomes higher and the saddle 16 becomes heavier. Thus, as the saddle 16 moves upwards, the deformation of the column 14 becomes larger. Thus, the straightness of the up and down movement of the saddle 16 cannot be maintained.

In addition, when the column 14 (column base 13) is moved on the bed 11 in the X axis direction, this movement of the column 14 is performed by the bed 11 and the guide rails 12a and 12b. Affects straightness. Thus, column 14 moves while experiencing angular variations (pitch, roll, and yaw). Thus, as shown in FIG. 5, the column 14 is inclined in the Z axis direction based on the junction between the column base 13 and the column 14.

3, the side walls 14b and 14d of the column 14 are different in wall thickness from each other because the guide rails 15a and 15b are formed in the side wall 14b. The thick side wall 14b and the thin side wall 14d differ from each other in heat capacity. Therefore, when heat is generated in the members of the driving means, the rotating means, the tool T, the workpiece W, and the like, and / or when a change in the temperature of the atmosphere in which the machine tool 1 is installed occurs, the heat capacity is increased. The side wall 14d whose heat capacity is smaller than the large side wall 14b tends to be thermally deformed. Thus, the column 14 is tilted in the X axis direction.

Occurrence of deformation of the column 14 in the X-axis direction and / or Z-axis direction may cause an error in the position of the tip end of the main axis 19, thereby lowering the machining accuracy of the workpiece W. FIG. Therefore, in the machine tool 1, the column deformation detection device 30 is provided in the column 14 so as to always directly detect the deformation of the column 14 which occurs in combination.

Specifically, when the saddle 16 is moved in the Y axis direction so that the column 14 is deformed in the X axis direction, and the temperature change of the atmosphere by the machine tool 1 itself and the machine tool 1 is installed. Assume that the heat generated by this causes thermal deformation of the column 14 in the X axis direction. In these cases, the distance from the distance sensor 40a to the measurement surface 37a is measured by the distance sensor 40a, and the distance from the distance sensor 40b to the measurement surface 38a is the distance sensor 40b. Is measured by And the measurement distance obtained in this way is input into NC device 50, and the difference between the measurement distances thus input is calculated by NC device 50. As shown in FIG. Then, based on the calculated difference between the measurement distances, the NC device 50 calculates the amount of deformation in the X axis direction of the column 14. Based on the deformation amount thus calculated, the NC device 50 corrects the drive of each drive means to perform position control of the tool T and the work piece W. FIG.

Further, suppose that the column 14 is moved in the X axis direction so that the column 14 is deformed in the Z axis direction. In this case, first, the distance from the distance sensor 41a to the measurement surface 37b is measured by the distance sensor 41a, and the distance from the distance sensor 41b to the measurement surface 38b is the distance sensor. It is measured by 41b. And the measurement distance obtained in this way is input into NC device 50, and the difference between the measurement distances thus input is calculated by NC device 50. As shown in FIG. Then, based on the calculated difference between the measurement distances, the NC device 50 calculates the amount of deformation in the Z axis direction of the column 14. Based on the deformation amount thus calculated, the NC device 50 corrects the drive of each drive means to perform position control of the tool T and the work piece W. FIG.

As described so far, according to the machine tool of the present invention, when the workpiece W is machined by the tool T, the column deformation detection apparatus 30 is used to determine the column 14 and the saddle 16. Deformation in the X-axis direction and the Z-axis direction of the column 14 caused at the time of movement is detected. After that, based on the detection result, the NC apparatus corrects the drive of each driving means to perform position control of the tool T and the workpiece W. FIG. Therefore, the fall of the processing precision can be prevented.

In the column deformation detection apparatus 30, the upper end portions of the suspension rods 35 and 36 are suspended from the hanging member 33 via the spherical bushing 34, respectively, with the hanging member 33 suspended by the wire 31. Is supported by. The lower end of the suspension rod 36 is also immersed in the oil 43 stored in the oil pan 42. Thus, even if disturbance vibration occurs in the column 14, the vibration of the suspension rods 35 and 36 can be attenuated in a short time, so that the suspension rods 35 and 36 can be held in the vertical direction in a stopped state. As a result, the distance sensors 40a, 40b, 41a and 41b measure, directly, quickly and accurately, the distances to the corresponding measured surfaces 37a, 37b, 38a and 38b of the measuring members 37 and 38. can do. In addition, the column deformation detection device 30 is provided in the column 14 to save space. Therefore, it is not necessary to enlarge the size of the machine tool 1 more than necessary.

The present invention is applicable to a heat deformation preventing structure configured to prevent the machining precision from being lowered by heat deformation of a column fixed to a machine tool such as a machining center.

Claims

In a machine tool for processing a workpiece by moving a tool and the workpiece relative to each other, the machine tool,
Saddle rotatably supporting a spindle with a removably fixed tool,
A column provided movably and movably supporting the saddle,
Column deformation detection means for detecting deformation of the column caused by movement of at least one of the saddle and the column, and
And correction means for correcting the movement of at least one of the tool and the workpiece based on the detection result of the column deformation detection means.

The work piece according to claim 1, wherein the column deformation detecting means includes a measuring part suspended vertically downwardly to the column, and measuring means for measuring a distance between the column and the measuring part. machine.

3. The machine tool as claimed in claim 2, wherein said column deformation detecting means includes damping means for damping vibrations of said portion to be measured.

The method of claim 1, wherein the column deformation detection means,
A container attached to the column and storing a viscous fluid,
A hanging member which is suspended vertically downwards on the column by a wire,
A first rod-shaped member, the upper end of which is supported by a hanging member via a spherical bushing, the first rod-shaped member including a measurement unit,
A second rod-shaped member, the second rod-shaped member having an upper end supported by a hanging member via a spherical bushing, the lower end being immersed in a viscous fluid stored in the container, and
And a distance sensor attached to the column to measure a distance from the distance sensor to the portion to be measured.

The machine tool according to any one of claims 1 to 4, wherein the column deformation detection means is provided inside the column.