KR102508280B1 - P0sition regulator for a central position of a tilting head in a machining center - Google Patents

Abstract

Disclosed is a rotation center correction device for a tilting head. The rotation center correction device is a tool offset measuring device that is built into the machine tool and protrudes into the machining area as needed, a tool offset attachment having a spherical contact part in contact with the tool offset measuring device and coupled to the rotating spindle, and a tool offset measuring device that is coupled to the rotating spindle. A detection unit for detecting first and second tool offsets representing positional errors of the tip of the tool mounted on the rotating spindle at the first and second rotational positions, respectively, and converting the first tool offset to the second rotational position by rotation and a calculation unit for generating an offset and obtaining an error vector, which is a positional error with respect to the center of rotation of the rotating spindle, from a difference between the second tool offset and the conversion offset. It can automatically detect and correct the correction position for the center of rotation of the rotating spindle.

Description

Rotation center correction device for tilting head {P0SITION REGULATOR FOR A CENTRAL POSITION OF A TILTING HEAD IN A MACHINING CENTER}

The present invention relates to a rotation center correction device for a tilting head, and more particularly, to a rotation center correction device for a tilting head for automatically correcting the rotation center of a tilting head for a machine tool.

Recently, with the development of the automobile, shipbuilding and aerospace industries, the demand for workpieces with complex shapes has increased, and the technology for processing large/small workpieces with complex shapes at once by machine tools using numerical control devices is developing. . The numerical control machine tool is movable in the x-axis and y-axis directions, and the tool is mounted on a tilting head that is rotatable around its own axis, and is movable along the z-axis direction and fixed to a table capable of self-rotation Complex shapes can be machined with a single machine tool.

In general, numerically controlled machine tools perform correction work to match the calculated position of a tool calculated by a numerical controller with the actual position, that is, the physical position of a tool located within the work area of the machine tool, before processing the workpiece. .

Components such as the table and spindle head of the machine tool and the column that fixes the spindle head are self-assembly errors and equipment errors due to temperature or operating life or the process of installing the workpiece on the table and installing the tool to the spindle head. Due to various error-inducing factors such as installation errors, the origin of the coordinate system recognized by the numerical controller and the origin of the actual coordinate system of the machine tool are misaligned.

Accordingly, a position error occurring at the tip of the tool is detected using a tool offset measuring device provided in the machine tool itself, and a correction operation is performed so that the origin of the coordinate system of the numerical controller coincides with the actual coordinate system. When the position of the tip of the tool is calculated based on the corrected coordinate system, the calculated position and the actual position of the tool are precisely matched to prevent interference between the tool and the workpiece.

However, when the spindle head itself rotates, an error regarding the center of rotation of the tilting head additionally occurs independently of the origin deviation of the coordinate system. Since the spindle of the tilting head is provided with a driving unit that rotates around its own axis of rotation, even when the origin point correction of the coordinate system is performed, the rotation center of the design stage recognized by the numerical controller due to the error inducing factor of the driving unit itself (hereinafter , The theoretical center) and the actual center of rotation of the spindle head (hereinafter, the actual center) do not match, resulting in center error.

If the position of the center of rotation of the tilting head is changed, the position of the tool at the end of the tool is different even for the same rotation angle, so that only the origin correction of the coordinate system is insufficient and the tool offset due to the rotation of the tilting head still needs to be corrected.

In order to compensate for the difference between the theoretical center and the actual center of the tilting head as described above, a center error detector composed of a spherical measuring fixture and measuring device is installed on the table of the machine tool separately from the tool offset measuring device to manually It detects the deviation between the theoretical center and the actual center.

However, the separate center error detector not only increases time and cost in the process of manually installing and removing the tool offset device, but also becomes an obstacle to accuracy and automation of measurement by detecting the center error by manual operation.

Accordingly, a means capable of automatically detecting and correcting a center error with respect to the rotational center of the tilting head is required.

An object of the present invention is to provide a rotation center correction device for a tilting head capable of automatically detecting and correcting a center error with respect to a rotation center of a tilting head using a tool offset device.

A tilting head rotation center correction device according to exemplary embodiments of the present invention for achieving the above object of the present invention includes a tool offset measuring device that is built into a machine tool and protrudes into a machining area as needed, and the tool offset measuring device A tool offset attachment having a spherical contact portion in contact with and coupled to the rotating spindle, first and second indicating positional errors of the tip of the tool mounted on the rotating spindle at different first and second rotational positions of the rotating spindle, respectively. A detection unit that detects a tool offset and rotates and converts the first tool offset to the second rotational position to generate a conversion offset, and determines the rotational center of the rotating spindle from the difference between the second tool offset and the conversion offset. and an arithmetic unit for obtaining an error vector, which is a positional error of

As an embodiment, the machine tool includes a correction coordinate system corrected by the tool offset detected from the tool offset measurement device, and the first and second tool offsets measure the spherical contact portion and the tool offset in the correction coordinate system. It is obtained by contacting the device.

As an embodiment, the operation unit does not include a first conversion unit that performs rotational conversion between the first and second tool offsets around the actual rotation center of the rotating spindle including the error vector, and the error vector. A second conversion unit generating the conversion offset by performing rotational conversion on the first tool offset around the theoretical rotation center of the rotating spindle, and the second tool offset and the conversion offset are expressed in Equation (1) below and a correction function unit that processes according to and calculates the error vector.

--- (1)

--- (One)

In Equation (1), (x1, z1) and (x2, z2) are the first and second rotation angles (θ ₁ ) and second rotation angles (θ ₂ ) on the xz plane of the machine tool. Indicates the first tool offset and the second tool offset detected at each rotational position, and (xc, zc) denotes a conversion offset generated by rotational transformation of the first tool offset.

As an embodiment, the first tool offset includes a horizontal offset detected when the rotation offset attachment is disposed parallel to the table of the machine tool and the first rotation angle θ ₁ is 0°, The second tool offset includes a vertical offset detected when the rotation offset attachment is disposed perpendicular to the table and the second rotation angle θ ₂ is 90°.

As an embodiment, the transform offset is calculated as in Equation (2) and the error vector is obtained as in Equation (3).

---- (2)

---- (2)

----- (3)

----- (3)

As an embodiment, the driving unit may further include a driving unit for driving the rotating spindle to offset the error vector so that an actual rotation center of the rotation spindle coincides with a theoretical rotation center, which is a designed rotation center.

As described above, the tilting head center position correction device according to exemplary embodiments of the present invention uses a tool offset measuring device and a tool offset attachment for correcting the coordinate system of a machine tool, and performs tool offset at first and second rotational positions. , and the detected tool offset can be used as basic data of an algorithm for detecting an error vector for the center of rotation of a rotating spindle. Accordingly, the spindle center error can be corrected by automatically detecting an error vector according to the algorithm of the rotation center correction device and reflecting the detected error vector to the rotating spindle for correction.

Accordingly, the machining accuracy and productivity of the machine tool can be remarkably improved by accurately correcting the center error without separate equipment or a complicated detection process for detecting the center error of the spindle rotation center. In particular, when the center error for the rotating spindle is required, the tool offset attachment is automatically mounted on the tilting head from the automatic tool changer (ATC) and only the tool offset is measured through the already installed tool offset measuring device, thereby detecting the center error and measuring the center error for the spindle. All corrections can be automated.

1 is a configuration diagram showing a tilting head center position correction device according to an embodiment of the present invention.
FIG. 2A is a diagram schematically showing a center error between a theoretical center and an actual center when the rotating spindle shown in FIG. 1 is rotated.
FIG. 2B is a diagram illustrating a change in tool offset due to a center error of the rotating spindle shown in FIG. 1;
3A to 3D are diagrams illustrating a process of detecting an error vector when the rotating spindle shown in FIG. 1 rotates at 90 degrees.

For the embodiments of the present invention disclosed in the text, specific structural or functional descriptions are only exemplified for the purpose of explaining the embodiments of the present invention, and the embodiments of the present invention may be implemented in various forms and the text It should not be construed as being limited to the embodiments described above.

Since the present invention can have various changes and various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific form disclosed, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle. Other expressions describing the relationship between components, such as "between" and "directly between" or "adjacent to" and "directly adjacent to", etc., should be interpreted similarly.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "comprise" or "having" are intended to indicate that the described feature, number, step, operation, component, part, or combination thereof exists, but that one or more other features or numbers are present. However, it should be understood that it does not preclude the presence or addition of steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, they are not interpreted in an ideal or excessively formal meaning. .

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail.

1 is a configuration diagram showing a tilting head center position correction device according to an embodiment of the present invention.

Referring to FIG. 1, a center position correcting device 500 for a tilting head according to an embodiment of the present invention is mounted on a rotating spindle S provided in a device H of a numerically controlled machine tool and is provided in the machine tool The tool offset attachment 100 having a spherical contact portion 120 in contact with the tool offset measuring device TO detects the tool offset, which is the positional error of the tip of the tool mounted on the rotating spindle S, to determine the center of rotation of the spindle. It consists of a control unit (C) that obtains and corrects the center error.

The tool offset attachment 100 includes a body 110 fixed to a rotating spindle S rotating around its own axis of rotation, such as a tilting head of a numerically controlled machine tool, and a spherical contact portion 120 fixed to the body 110 ) is composed of

For example, the tool offset attachment 100 may be aligned with other tools in a tool box and coupled to the spindle S by an automatic tool changer (ATC). When position correction with respect to the center of rotation of the rotating spindle is required, the tool offset attachment 100 may be called through an automatic tool changer and automatically mounted on the spindle S.

A contact portion 120 for detecting the tool offset is provided at an end of the body 110 fixed to the spindle S. The contact part 120 is formed of a spherical ball so that the contact distance between the contact part 120 and the tool offset measurement device TO is constant regardless of the rotation of the spindle S to which the body 110 is fixed. can keep That is, although the contact point between the contact part 120 and the tool offset measurement device TO varies according to the rotation angle of the spindle S, the distance between them is the radius of the spherical ball constituting the contact part 120. , so it always remains constant. Accordingly, a tool offset, which is a positional error of the tip of the tool, can be detected independently of the rotation angle of the rotating spindle (S).

For example, the tilting head is provided in a numerically controlled machine tool that is automatically driven by numerical control, and a workpiece fixed on a table is machined in a multi-axis direction by a tool fixed to the tilting head. Accordingly, the tool mounted on the tilting head not only moves along the length (z), width (y), and height (x) directions of the bed, but also rotates the rotating spindle constituting the tilting head to produce a constant motion with respect to the workpiece. It can also be processed in a tilted state.

At this time, coordinate system correction, which detects and corrects a positional error between the origin of the coordinate system recognized by the numerical controller and the origin of the actual coordinate system of the machine tool, is performed before processing the workpiece to prevent interference between the tool and the workpiece.

In this embodiment, the coordinate system correction is performed by automatically detecting a tool offset, which is a positional error of the front end of a tool fixed to the rotating spindle S, and resetting the origin of the coordinate system to offset the detected tool offset.

For example, the tool offset may be automatically detected by a tool offset measuring device TO provided in the body B of the machine tool (not shown). The tool offset measurement device (TO) having its own guiding surface is provided with a driving cylinder and protrudes into the processing area of the bed only when tool offset measurement for a tool is required, and when the measurement is completed, the body (B) It has a structure that is embedded in the interior of.

In particular, a head sensor (not shown) for tool offset detection is disposed in the tool offset measurement device TO, and when the head sensor and the tool come into contact, the coordinates of the contact point are transmitted to the numerical controller to correct the position of the tip of the tool. provided as data.

After correcting the origin of the coordinate system of the machine tool using the tool offset detected by the tool offset measurement device TO, the control unit C detects the tool offset for coordinate system origin correction. ) is used to automatically detect the center error, which is the error between the theoretical center and the actual center of the rotating spindle (S).

As an embodiment, the control unit (C) is the first and second tool position error of the tip of the tool mounted on the rotating spindle (S) at different first and second rotational positions of the rotating spindle (S), respectively. A detection unit 200 that detects a tool offset, rotates and converts the first tool offset to the second position to generate a conversion offset, and calculates the difference between the second tool offset and the conversion offset as the center of rotation of the rotating spindle The operation unit 300 obtained by the center error, which is a positional error related to , and the driving unit 400 that drives the rotating spindle S to offset the center error and matches the actual center of the rotating spindle S with the theoretical center. provide

The detection unit 200 is connected to the control panel (not shown) of the numerical controller and stores the rotation angle θ of the rotating spindle S, according to the rotation angle storage unit 210 and the spindle rotation angle θ. A drive signal generator 220 for generating a spindle driving signal for driving the rotating spindle (S) and a measuring device driving signal for driving the tool offset measuring device (TO) and the open body (B) of the machine tool A tool offset storage unit 230 is provided which is connected to the head sensor of the tool offset measuring device TO and stores tool offsets detected for different rotational angles of the spindles S.

The spindle rotation angle θ may be manually input by an operator or automatically calculated and transmitted by the numerical controller. The input or transmitted spindle rotation angle θ is stored in the rotation angle storage unit 210 .

At this time, since the positional error of the spindle rotation center is caused by the rotation of the spindle S, the first and second tool offsets are detected at different first and second rotational positions, respectively. Accordingly, the spindle rotation angle θ is divided into a first rotation angle θ specifying the first rotation position, which is the reference point of rotation, and a second rotation angle θ ₂ specifying the second rotation position, which is the end point of rotation. It is divided and stored in the rotation angle storage unit 210 .

The driving signal generator 220 prepares for tool offset detection by driving the rotating spindle S of the tilting head and the driving offset measuring device TO according to the tool offset detection signal. When the tool offset attachment 100 is mounted on the rotating spindle S by a numerical controller and the spindle rotation angle θ is set, a spindle drive signal and a measurement device drive signal are generated by the drive signal generator 220. do.

Accordingly, the rotating spindle (S) to which the tool offset attachment 100 is mounted rotates by a first rotational angle (θ ₁ ) and moves to the first rotational position, and measures the tool offset disposed inside the body (B). The device TO is discharged into the processing area of the bed. Therefore, both the tool offset attachment 100 and the tool offset measuring device TO are disposed in the machining area of the machine tool. The spindle driving signal and the measuring device driving signal may be manually input by an operator or automatically transmitted by a numerical controller.

In this embodiment, the spindle driving signal drives the rotating spindle S to rotate on the x-z plane of the coordinate system. However, it is self-evident that the plane of rotation of the rotating spindle S is optional and it is possible to drive the rotating spindle S to rotate on the y-z plane. Even in the case of rotation on the y-z plane, the center error with respect to the rotation center of the spindle can be obtained by the same process as described below.

In the machining area, the contact part 120 of the tool offset attachment 100 is brought into contact with the tool offset measuring device TO to detect a first tool offset and store it in the tool offset storage part 230 . For example, at the first rotational position, the spherical contact part 120 contacts the head sensor disposed on the contact surface perpendicular to the x-axis and z-axis, respectively, and sets the first tool offset (x ₁ , z ₁ ) is detected. In this embodiment, the contact coordinates at the moment when the contact ball of the contact part 120 and the contact surface of the tool offset measurement device (TO) come into contact are detected through the head sensor, and the contact coordinates are respectively in the x-axis and z-axis directions. It is stored in the first storage unit 231 as offset coordinates.

Subsequently, the rotating spindle S rotates at a second rotation angle θ ₂ greater than the first rotation angle θ ₁ by a spindle driving signal, and further rotates to a second rotation position. When the rotation to the second rotation position is completed, the second storage unit 232 detects the tool offset at the second position by bringing the contact unit 120 into contact with the tool offset measuring device TO. save to For example, at the second rotational position, the spherical contact part 120 contacts the head sensor disposed on the contact surface perpendicular to the x-axis and z-axis, respectively, and sets the second tool offset (x ₂ , z ₂ ) is detected.

In this case, the first and second storage units 231 and 232 may be individually connected to the rotation angle storage unit 210 so that each tool offset and the spindle rotation angle θ may be connected to a tag.

2A is a diagram schematically showing the center error between the theoretical center and the actual center when the rotating spindle shown in FIG. 1 is rotated, and FIG. 2B is a change in tool offset due to the center error of the rotating spindle shown in FIG. 1 is a drawing representing

Referring to Figures 2a and 2b, when rotating the rotating spindle (S) even after the origin correction of the coordinate system, due to the error inducing factor of the tilting head structure itself, the rotational center of the rotating spindle (S) is the theoretical center O (X, Y) It is shifted by the error vector E (α, β) from , and is located at the actual center O' (X + α, Y + β).

Accordingly, when the tool offset attachment 100 is mounted on the rotating spindle S and the tool offset is measured at the position before and after the rotation of the rotating spindle S, the magnitude of the rotation angle Δθ and the error vector E (α, β) ), the size of the tool offset varies.

The case where the rotation center of the rotating spindle (S) is located at the theoretical center O(X,Y) is set as the rotation start point, and the case where the rotation center is located at the actual center O'(X+α,Y+β) is set as the rotation end point. In this case, the rotating spindle (S) rotates from an arbitrary reference position by a first rotation angle (θ ₁ ) to rotate from the reference position to the first rotational position having a rotation center at the theoretical center O(X,Y). It can be modeled as rotating by 2 rotation angles (θ ₂ ) to a second rotation position having a rotation center at the actual center O' (X+α, Y+β).

Therefore, when the rotating spindle S is located at the first rotational position, the tool offset is detected as the first tool offset T ₁ (x ₁ , z ₁ ), and when located at the second rotational position, the tool offset is It is detected as the second tool offset T ₂ (x ₂ , z ₂ ). When the equipment error of the tilting head structure itself does not occur, the first and second tool offsets will be detected as the same value regardless of the first and second rotational positions. However, in practice, since the theoretical position and actual position of the rotating spindle (S) are different due to inherent equipment errors of the tilting head structure, tool offsets are different due to rotation.

The calculation unit 300 rotates and converts the first tool offset T ₁ (x ₁ , z ₁ ) to the second rotational position to generate a conversion offset, and generates a conversion offset with the second tool offset T ₂ (x ₂ , z ₂ ). An error vector, which is a positional error with respect to the center of rotation of the rotating spindle (S), is obtained from the difference between the conversion offsets.

For example, the calculation unit 300 includes a first conversion unit 310 that performs rotation conversion between the first and second tool offsets T ₁ and T ₂ around the actual center, and the theoretical center. A second conversion unit 320 generating the conversion offset by performing rotational conversion on the first tool offset T ₁ and a correction function unit calculating the error vector from the second tool offset and the conversion offset. (330).

The first conversion unit 310 obtains a relationship between the first and second tool offsets T ₁ and T ₂ detected by rotation conversion. The actual center O' (X+α,Y+β) of the rotating spindle S _{from the first rotational position having the first rotational angle θ 1 to} the second rotational position having the second rotational angle θ2 While rotating clockwise around , the position of the tool tip moves from the first tool offset (T ₁ ) to the second tool offset (T ₂ ).

Therefore, the first and second tool offsets T ₁ and T ₂ satisfy Equations (1) and (2) by rotation conversion.

--- (1)

--- (One)

).(step,

).

If R is the rotation transformation matrix according to the rotation of the rotating spindle S in the clockwise direction,

로 표시된다.

is indicated by

---- (2)

---- (2)

The second conversion unit 320 is a virtual tool offset generated when the first tool offset (T ₁ ) moves from the first rotational position to the second rotational position around the theoretical center of the rotating spindle (S). is created as a conversion offset. Therefore, the conversion offset is the position at which the first tool offset T ₁ is converted by the rotation of the rotating spindle S when it is assumed that the theoretical center and the actual center coincide with each other because there is no equipment error of the tilting head structure indicates

Accordingly, the conversion offset T _c (x _c , z _c ) of the first tool offset T ₁ by the second conversion unit 320 is obtained as follows.

------ (3)

------ (3)

The correction function unit 330 calculates the error vector E(α,β) using the second tool offset (T ₂ ) and the conversion offset (T _c ). Even though the first tool offset (T ₁ ) is rotated by the same rotation angle, when it is rotated around the theoretical center (O), it is converted into a conversion offset (T _c ) and rotated around the actual position (O'). In this case, it is converted into the second tool offset (T ₂ ).

Therefore, the difference between the second tool offset (T ₂ ) and the conversion offset (T _c ) becomes a rotation conversion component by the error vector E (α, β).

Equation (2) - Performing equation (3),

--- (4)

--- (4)

--- (5)

--- (5)

According to Equations (4) and (5), the error vector E(α,β) is given as a function of only the rotation angle θ regardless of the coordinates of the theoretical center O of the rotating spindle S. Therefore, when the first and second tool offsets T ₁ and T ₂ are detected by the tool offset attachment 100 and the rotation angle of the rotating spindle is set, an error vector for the rotation angle can be automatically obtained. .

3A to 3D are diagrams illustrating a process of detecting an error vector when the rotating spindle shown in FIG. 1 rotates at 90°. 3A and 3B show that the rotation offset attachment 100 is disposed parallel to the table of the machine tool and detects a first tool offset (horizontal offset) in a state where the first rotation angle θ ₁ is 0˚. 3C and 3D are diagrams in which the rotation offset attachment 100 is disposed perpendicularly to the table of the machine tool and the second rotation angle θ ₂ is rotated by 90 degrees in a counterclockwise direction. It is a drawing showing tool offset (vertical offset) detection.

3A and 3B, the spherical contact part 120 and the x-axis and z-axis head sensor H1 of the tool offset measuring device TO at the first rotational position where the tool offset attachment 100 is horizontally disposed , H2)) respectively. Accordingly, T1 (x1, z1), which is the first tool offset in the horizontal state, is detected as the horizontal offset. The contact coordinates at the moment when the contact ball of the contact part 120 and the head sensors H1 and H2 of the tool offset measuring device TO contact each other are detected through the head sensor, and the contact coordinates are in the x-axis and z-axis directions, respectively. It is stored in the first storage unit 231 as a horizontal offset coordinate of .

Subsequently, as shown in FIGS. 3C and 3D , the rotating spindle S is rotated by 90° (ie, -270°) to move to a second rotational position having a second rotational angle θ ₂ . When the rotation to the second rotational position is completed, the second tool offset T ₂ (x ₂ , z ₂ ), which is the tool offset at the second rotational position, is measured by bringing the contact part 120 into contact with the tool offset measuring device TO. It is detected as a vertical offset and stored in the second storage unit 232 . For example, at the second rotational position, the spherical contact part 120 comes into contact with the x-axis and z-axis and the head sensors H1 and H2, respectively, so that the second tool offset T ₂ ( x ₂ , z ₂ ) is detected.

Assuming that the coordinates of the tool offset measuring device TO are the origin, the conversion offset of the horizontal offset is obtained as shown in Equation (6) below by Equation (3).

----- (6)

----- (6)

Therefore, the error vector E(α,β) is obtained as Equation (7) below by Equation (5).

----- (7)

----- (7)

Accordingly, the center error can be automatically and accurately detected using the tool offset measuring device TO provided in the machine tool without any additional equipment for detecting the center error of the rotating spindle S. In addition, by automatically reflecting the detected error vector to the rotating spindle (S), the spindle rotation error can be detected and corrected automatically and accurately.

The driving unit 400 drives the rotating spindle S to offset the error vector E so that the actual center of the rotating spindle S coincides with the theoretical center. When the origin point correction for the coordinate axis is performed first, since the relative positions of the equipment elements driven in the processing area of the machine tool are specified by the numerical controller, the rotation spindle itself is driven to drive the actual center to coincide with the theoretical center. The error vector (E) can be removed. Accordingly, since the center of rotation of the rotating spindle (S) can also be uniquely specified based on the origin of the coordinate system of the machine tool, the coordinates of the tip of the tool calculated by the numerical controller are subject to deviation due to the rotation of the spindle (S). prevent that

In the case of this embodiment, the driving unit 400 is provided separately as a component of the rotation center correction device 500, but it is obvious that it may include a driving element of a numerical controller that drives the machine tool.

The theoretical rotation center and actual rotation on the X-Z plane of the coordinate axis by setting the height direction, which is the direction of the column structure (not shown) to which the tilting head is fixed, as the x-axis direction, and setting the movement direction of the table to which the workpiece is fixed as the z-axis direction Although the rotational movement relationship between the centers is disclosed as an example, it is possible to obtain and correct the positional deviation in the same process as described above for the Y-Z plane limited to the Y-axis direction and the Z-axis direction, which is the width direction of the table. self-explanatory

As described above, the tilting head center position automatic correction device detects the tool offset at the first and second rotational positions by using the tool offset measuring device and the tool offset attachment for correcting the coordinate system of the machine tool, and the detected tool offset It can be used as basic data of an algorithm for detecting an error vector related to the center of rotation of a rotating spindle. Accordingly, the spindle center error can be corrected by automatically detecting an error vector according to the algorithm of the rotation center correction device and reflecting the detected error vector to the rotating spindle for correction.

Accordingly, the machining accuracy and productivity of the machine tool can be remarkably improved by accurately correcting the center error without separate equipment or a complicated detection process for detecting the center error of the spindle rotation center. In particular, if the center error for the rotating spindle is necessary, the tool offset attachment is automatically mounted on the tilting head from the automatic tool changer (ATC) and only the tool offset is measured through the already installed tool offset measurement device to detect center error and compensate for the spindle. can all be automated.

Although the above has been described with reference to the embodiments of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention described in the claims below. You will understand that you can.

Claims (6)

A tool offset measuring device built into the machine tool and protruding into the machining area as needed;
a tool offset attachment having a spherical contact portion contacting the tool offset measuring device and coupled to a rotating spindle;
a detector configured to detect first and second tool offsets representing positional errors of a tip of a tool mounted on the rotating spindle at different first and second rotational positions of the rotating spindle; and
An operation unit generating a conversion offset by rotationally converting the first tool offset to the second rotational position and obtaining an error vector, which is a positional error with respect to the center of rotation of the rotating spindle, from a difference between the second tool offset and the conversion offset. include,
The machine tool has a correction coordinate system corrected by the tool offset detected from the tool offset measurement device, and the first and second tool offsets are obtained by contact between the spherical contact portion and the tool offset measurement device in the correction coordinate system. is obtained,
The operation unit includes a first conversion unit for performing a rotation conversion between the first and second tool offsets around the actual rotation center of the rotation spindle including the error vector, and the rotation spindle without the error vector. A second conversion unit generating the conversion offset by performing rotational conversion on the first tool offset around the theoretical rotation center, and processing the second tool offset and the conversion offset according to Equation (1) below to obtain the A rotation center correction device for a tilting head including a correction function unit that calculates an error vector.

--- (One)

(However, (x ₁ , z ₁ ) and (x ₂ , z ₂ ) are the first and second rotation angles (θ ₁ ) and second rotation angles (θ ₂ ) on the xz plane of the machine tool. Indicates the first tool offset and the second tool offset detected at 2 rotational positions, respectively, and (x _c , z _c ) denotes a conversion offset generated by rotation conversion of the first tool offset.) delete delete The method of claim 1, wherein the first tool offset includes a horizontal offset detected when the tool offset attachment is disposed parallel to the table of the machine tool and the first rotation angle (θ ₁ ) is 0°, The second tool offset includes a vertical offset detected when the tool offset attachment is disposed perpendicularly to the table and the second rotation angle (θ ₂ ) is 90°. 5. The rotation center correcting device for a tilting head according to claim 4, wherein the conversion offset is calculated as in Equation (2) and the error vector is obtained as in Equation (3).

---- (2)

----- (3) The rotation center correction device for a tilting head according to claim 1 , further comprising a driving unit driving the rotation spindle to offset the error vector so as to match an actual rotation center of the rotation spindle with a theoretical rotation center, which is a design rotation center.

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