KR101266165B1

KR101266165B1 - Calibration Position Device For Thin Tube Of Laser Processing

Info

Publication number: KR101266165B1
Application number: KR1020100138664A
Authority: KR
Inventors: 김병섭; 신우철; 노승국; 박종권
Original assignee: 한국기계연구원
Priority date: 2010-12-30
Filing date: 2010-12-30
Publication date: 2013-05-21
Also published as: KR20120076899A

Abstract

The present invention, the base 100: the rotating body XYZ stage 200 is installed so as to be movable in the X, Y, Z axis direction on the upper surface of the base 100, the operation control by the control unit 700: the rotation Rotor 300 installed in the entire XYZ stage 200, fixed to the workpiece (M), the operation controlled by the control unit 700 to rotate the workpiece (M) about the axis: the rotating body XYZ stage Sensor block XYZ stage 400 disposed on the opposite side of the base and movable in the X, Y, Z-axis direction from the upper surface of the base 100: installed in the sensor block XYZ stage 400 in the longitudinal direction Sensor block 500 for measuring the runout of the workpiece (M) through the runout sensor 410 wrapped around the outer surface of the projected workpiece (M) and outputs a measurement value: to the sensor block XYZ stage 400 It is installed, the operation control by the control unit 700 for processing the workpiece (M) through the laser Laser 600: Receives the measured value from the runout sensor 410 and calculates a correction value according to the runout displacement of the workpiece (M) through mutual comparison with the reference value already set, the rotating body XYZ through the correction value And a controller 700 for operation control of the stage 200 to correct an error due to a runout displacement.
According to an embodiment of the present invention, the runout of the workpiece generated during rotation is measured using a runout sensor, the measured value is transmitted to the controller, and the controller calculates a correction value through mutual comparison with the set value. By correcting the position of the rotating body XYZ stage holding the workpiece, there is an advantage that the laser for processing can be precisely processed without losing focus on the workpiece.

Description

Calibration Position Device for Thin Tube Of Laser Processing

The present invention relates to a position correction device for laser processing of a thin tube, and to explain in more detail, the runout of the workpiece is measured (detected) through the runout sensor and outputs the measured value to the controller, and The laser is a thin tube that can be processed precisely without losing the focus on the workpiece by correcting the position of the rotating body XYZ stage holding the workpiece by calculating a correction value through mutual comparison with the set value. A position correction device for machining.

Recently, with the development of medical technology, the medical demand for microfabricated parts is increasing. One of them is a catheter and a stent used in brain or heart surgery. These products can be used to pattern drugs for drug delivery, vessel support, etc. by laser or electronic distance measurement (EDM) on metal tubes of several millimeters (mm) or hundreds of micro (μm) diameter (hereinafter referred to as workpieces). Is processed. The processing on such a workpiece is easy due to the small diameter of the workpiece and can be easily bent because of difficulty in mounting the workpiece and runout due to rotation of the workpiece, even if non-contact processing such as laser processing without direct contact with the workpiece is used. Laser processing is not easy

The above-mentioned run out means that the central axis of the rotating body rotates and is shaken by a predetermined displacement while the rotating body rotates, and is generally caused by an imbalance, external force or shape error of the rotating body.

Methods for measuring such runout are largely divided into a contact method and a non-contact method.

The contact method is a device for directly contacting and measuring a workpiece. Typically, a dial gauge, a pressure gauge generally referred to as an indicator, and an electric micrometer are used.

However, the contact methods are not applicable to the measurement of the runout to the workpiece in the high-speed rotation state, and moreover, if the contact type measuring device is easily installed in the workpiece of several millimeters (mm) or hundreds of micro (μm) in diameter. Because of the warping problem, it could not be applied further.

On the other hand, the non-contact method is a device for measuring by using the optical in a state arranged adjacent to the workpiece, typically using an eddy current sensor, a capacitive sensor, an optical sensor.

The non-contact measuring instruments are capable of high-speed measurement of the workpiece, but in general, the non-contacting method using a field requires a target measuring area that is 30% larger than the cross section of the sensor to be measured, Therefore, a noise called electrical runout may occur. In particular, there is a problem in that performance such as sensitivity and measurement area changes depending on the diameter (size) of the workpiece to be measured.

In the case of the eddy current type sensor or the capacitive type sensor, it is possible to measure only the workpiece having a diameter of 2 to 3 times larger than the diameter of the measuring probe, and thus the runout of the workpiece having a diameter of several millimeters (mm) or several hundred micro (μm) can be measured. There is a limit of impossible measurement.

The optical sensor may be classified into a reflective type and a transmissive type. The reflective type is sensitive to the surface roughness and surface characteristics of the reflective surface, and the transmissive type has a problem in that resolution below the pixel size of the image sensor cannot be obtained.

The present invention has been made to solve the above problems, and measures (detects) and corrects the runout displacement of a relatively thin workpiece in a few micrometers or several micro units, and precisely processes the workpiece by using a laser. It is an object of the present invention to provide a position correction device for laser processing of thin tubes.

According to an aspect of the present invention,

Base:

Rotor body XYZ stage is installed on the upper surface of the base so as to be movable in the X, Y, Z axis direction, the operation control by the control unit:

A rotating body installed on the rotating body XYZ stage, the workpiece being fixed, and controlled by a control unit to rotate the workpiece about an axis;

A sensor block XYZ stage disposed on the opposite side of the rotating body XYZ stage and installed to be movable in the X, Y, and Z axes in the upper surface of the base:

A sensor block installed on the sensor block XYZ stage and surrounding the outer surface of the workpiece protruding in the longitudinal direction to measure a runout of the workpiece through a runout sensor to output a measured value;

A processing laser is installed on the sensor block XYZ stage, and is controlled by a control unit to process a workpiece through a laser.

The measured value is inputted from the runout detection sensor to calculate a correction value according to the runout displacement of the workpiece through mutual comparison with a preset reference value, and by operating the rotating body XYZ stage based on the correction value, the error according to the runout displacement is determined. And a control unit for correcting.

According to an embodiment of the present invention, the runout of the workpiece generated during rotation is measured using a runout sensor, the measured value is transmitted to the controller, and the controller calculates a correction value through mutual comparison with the set value. By correcting the position of the rotating body XYZ stage holding the workpiece, there is an advantage that the laser for processing the workpiece can be precisely processed without losing focus on the workpiece.

1 to 4 is a combined perspective view, an exploded perspective view, a front view and a right side view of the position correction device for the laser processing of the thin tube according to the present invention.
Figure 5 is a block diagram showing the correlation between each component in the position correction device for laser processing of a narrow tube according to the present invention.
6a and 6b show an embodiment of a position correction device for the laser processing of the narrow tube according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail.

1 to 4, the position correction device for the laser processing of the narrow tube according to the present invention, the base 100, the rotating body XYZ stage 200, the rotating body 300, the sensor block XYZ stage ( 400, the sensor block 500, the processing laser 600, and the control unit 700.

The base 100 is a plate which is generally rectangular in shape. As illustrated in FIG. 2, guide parts 101 and 101 ′ are formed on the upper surface side by side, and moving member insertion parts 102 and 102 ′ are formed between the guide parts 101 and 101 ′ formed side by side. In addition, lead screws 111 and 111 'are installed at the moving member insertion parts 102 and 102', and in the case of the lead screws 111 and 111 ', one end is fixed to the base 100 to be freely rotatable and the other end protrudes outward. . In particular, in the other end of the protruding lead screw (111, 111 ') can be rotated by the operator manually or by the driving means, that is, by installing the first driving unit 110 and the first' drive unit 110 'automatically rotated. In the case of the first driving unit 110 and the first 'drive unit 110', the operation is controlled by the controller 700.

In the present embodiment, the guide portion 101 and the moving member inserting portion 102 formed on the left side of the base 100 move with a pair of guide rails 211 formed on the bottom surface of the rotating Z-axis transfer frame 210. A member 212 is movably installed, and a pair formed on the bottom surface of the sensor block Z-axis transfer frame 410 in the guide portion 101 'and the movable member insertion portion 102' formed on the right side of the base 100. The guide rail 411 and the moving member 412 is installed to be movable.

The rotating body XYZ stage 200 is composed of a rotating body Z axis moving frame 210, a rotating body X axis moving frame 220 and a rotating body Y axis moving frame 230, the operation control by the control unit 700 The rotating body Z-axis feeding frame 210 and the rotating body X-axis feeding frame 220 and the rotating body Y-axis feeding through the first driving unit 110, the second driving unit 215 and the third driving unit 224 The frame 230 is moved to adjust the position of the rotating body 300.

The rotating body Z-axis transfer frame 210 is a member having an overall shape of a rectangular shape, which is installed to be movable in the Z-axis direction on the base 100, a pair of guide rails 211 is formed on the bottom surface, A moving member 212 is installed between the pair of guide rails 211 to be movable on the lead screw 111 of the base 100. In addition, a pair of guide portions 213 are formed on the upper surface along the longitudinal direction, and a moving member insertion portion 214 is formed between the pair of guide portions 213. In particular, the lead screw 215a is rotatably installed inside the moving member inserting portion 214. The second driving part 215 is installed at the protruding portion of the lead screw 215a.

The rotating body X-axis transfer frame 220 is a member having an overall shape of a rectangular parallelepiped shape, is opened forward, and is installed on the rotating body Z-axis transfer frame 210 to be movable in the X-axis direction. A pair of guide rails 221 are formed, and a moving member 222 is installed between the pair of guide rails 221. In particular, the guide portion 223 corresponding to the guide rail 231 of the rotating Y-axis transfer frame 230 to be described later is formed on the opened inner surface. The lead screw 224a is vertically installed in the rotating X-axis transfer frame 220, but the other end of the lead screw 224a protrudes upward to allow the operator to operate the lead screw 224a. In particular, a third driving part 224 is installed at the protruding portion of the lead screw 224a.

The rotating body Y-axis transfer frame 230 is a member having an overall shape of a rectangular shape, the member is installed to be movable in the Y-axis direction to the rotating body X-axis transfer frame 220, the above-mentioned rotating body X on both sides A guide rail 231 corresponding to the guide portion 223 of the shaft transfer frame 220 is formed, and a moving member 232 is formed on the rear surface thereof so as to be movable on the lead screw 224a.

On the other hand, the rotating body Z-axis feed frame 210, the rotating body X-axis feed frame 220 and the rotating body Y-axis feed frame 230 constituting the rotating body XYZ stage 200 is a lead screw protruding outward ( Although it is possible to manually feed the 111, 215a, and 224a to each of the Z, X, and Y axis directions, the driving means, that is, the first, The first driving unit 110, the second driving unit 215, and the third driving unit 224 are provided, and they are controlled by the correction values of the control unit 700, respectively, so that rapid and precise transfer control can be realized.

The rotating body 300 is installed on the rotating body XYZ stage 200, and fixes the workpiece (M), the operation is controlled by the control unit 700 serves to rotate the workpiece (M) about the axis. . In particular, the rotating body 300 is a driving motor 310 formed on one side is installed in the rotating Y-axis transfer frame 230, the shaft is connected to the driving motor 310, the fixing part for fixing the workpiece (M) 320 is exposed to the outside. In the case of the fixing part 320 for fixing the workpiece M, a detailed description thereof will be omitted since it is a well-known technique widely used in the art. In the case of the drive motor 310, various known driving means may be applied according to the processing purpose of the workpiece (M).

Next, the sensor block XYZ stage 400, the sensor block 500, the processing laser 600, and the control unit 700 will be described.

The sensor block XYZ stage 400 is composed of a sensor block Z axis transport frame 410, a sensor block X axis transport frame 420 and a sensor block Y axis transport frame 430, the rotating body XYZ stage 200 It is disposed on the opposite side of the base 100 is installed to be movable in the X, Y, Z axis direction. The sensor block XYZ stage 400 is also operation controlled by the control unit 700 serves to adjust the position of the sensor block 500.

Referring to FIG. 2, the sensor block Z-axis transfer frame 410 has an overall shape of a rectangular shape, and a pair of guide rails 411 are formed on a bottom thereof, and a pair of guide rails 411 is formed between the sensor blocks. The moving member 412 is formed. In addition, a pair of guide portions 413 are formed on the upper surface along the longitudinal direction, and a movable member insertion portion 414 is formed between the pair of guide portions 413. In particular, the lead screw 415a is installed to protrude outwardly from the moving member inserting part 414, and the second 'driving part 415 is installed at the protruding portion and is controlled by the controller 700. In the present embodiment, the pair of guide rails 411 are movably installed in the guide portion 101 'formed in the base 100, and the movable member 412 is movably installed in the lead screw 111'. . Accordingly, when the first driving unit 110 ′ is operated, the lead screw 111 ′ is rotated about the axis to move (transfer) the sensor block Z axis transfer frame 410 in the Z axis direction.

The sensor block X-axis transfer frame 410 has a rectangular parallelepiped shape as a whole, one side of the outer surface is open, and is installed to be moved in the X-axis direction on the sensor block Z-axis transfer frame 410. In the case of the sensor block X-axis transfer frame 410, a pair of guide rails 421 corresponding to the guide portion 413 of the sensor block Z-axis transfer frame 410 is formed, a pair of guide rails ( A moving member 422 is formed between the 421s so as to be movable on the lead screw 415a installed in the moving member inserting part 414. In particular, the guide portion 423 corresponding to the guide rail 431 of the sensor block Y-axis transfer frame 430 to be described later is formed on the open inner surface. In addition, a lead screw 424a is vertically installed in the sensor block X-axis transfer frame 410, and the other end of the lead screw 424a protrudes upward, and the protruding portion is controlled by the control unit 700. The third 'drive unit 424 is installed. Further, the outer surface of the sensor block X-axis transfer frame 410 is provided with a processing laser 600 for processing the workpiece (M) via a laser.

Subsequently, the sensor block Y-axis transfer frame 430 has an overall shape of a rectangular parallelepiped, and a guide rail corresponding to the guide part 423 formed on the inner side of the sensor block X-axis transfer frame 410 on both sides thereof. 231 is formed, and at the rear, a moving member 423 is formed to be movable on the lead screw 424a. In particular, the front of the sensor block Y-axis transfer frame 430 is fixed to the sensor block 500 is mounted on the run-out detection sensor 510 to be described later.

On the other hand, in the case of the other end portion of the lead screw (111 ', 415a, 424a) protruding outward, the operator may manually operate the outer surface through the knurling operation, in the present embodiment, the first end portion of the lead screw ( The driving unit 110 ', the second' driving unit 414, and the third 'driving unit 424 are installed, and the first' driving unit 110 'and the second' driving unit 414 and the third 'driving unit 424 are installed. The operation is controlled by the control unit 700.

Referring to FIG. 4, the sensor block 500 is installed on the sensor block XYZ stage 400 to wrap the outer surface of the workpiece M protruding in the longitudinal direction, and to process the workpiece M through the runout detection sensor 410. It measures (detects) the runout of) and outputs the measured value.

The sensor block 500 has a rectangular shape in overall shape, and one side and the center of the edge penetrate through the sensor block 500. In addition, the sensor block 500 is installed to be exposed toward the center through which the runout detection sensor 510 measuring (detecting) the runout (Runout) of the workpiece M is described in more detail. same.

The runout detection sensor 510 includes a first light emitter 511a, a first light receiver 511b and a second light emitter 512a, and a second light receiver 512b corresponding thereto.

The first light emitting unit 511a and the second light emitting unit 512a are light emitting components (devices). The light source includes a light emitting diode (LED) and an infrared ray emitting diode (IRED). In this embodiment, the laser diode (LD), a general halogen lamp, and the like may be used. In this embodiment, a laser diode (LD) is applied.

The first light receiving unit 511b and the second light receiving unit 512b are components (devices) for receiving light provided from the first light emitting unit 511a and the second light emitting unit 512a and converting the light into an electrical signal. The photodiode includes a photo diode, a photo transistor, and a photo detector. In this embodiment, a photo diode is applied.

In particular, the first light emitting unit 511a, the first light receiving unit 511b, the second light emitting unit 512a, and the second light receiving unit 512b may be alternately disposed so as not to cross each other so that interference between light sources does not occur. .

Briefly describing the principle of the runout detection sensor 410, when the rotating body 300 is rotated by the driving means, the workpiece (M) fixed to the rotating body 300 also rotates together, The workpiece (M) has a runout motion that is finely shaken in all directions by deflection and centrifugal force caused by its own weight. Therefore, the degree of blocking light from the first light emitting part 511a to the first light receiving part 511b and the light from the second light emitting part 512a to the second light receiving part 512b is changed by the runout motion. .

For example, as illustrated in FIG. 6B, the workpiece M may receive light from the first light emitting portion 511a to the first light receiving portion 511b and the second light receiving portion 512a may be disposed in the second light receiving portion (512a). In the state disposed adjacent to the light directed to 512b, the runout detection sensor 510 does not output any detection signal. However, as shown in FIG. 6A, light directed from the first light emitting portion 511a to the first light receiving portion 511b and light from the second light emitting portion 512a to the second light receiving portion 512b are processed. When a part is blocked by the run-out motion of), since the first light receiving part 511b and the second light receiving part 512b naturally receive only a little light, the electrical signal is also changed. Therefore, by measuring the change in the electrical signal it is possible to measure the displacement of the runout of the workpiece (M) easily and precisely even if the workpiece (M) is miniaturized and rotates at high speed.

Meanwhile, light emitting part optical fibers 513a and 514a are disposed on the first light emitting part 511a, the second light emitting part 512a, the first light receiving part 511b, and the second light receiving part 512b of the runout detection sensor 510. And the light receiving part optical fibers 513b and 514b are further provided with reinforcement.

The optical fiber refers to an optical fiber that uses a glass having a high refractive index at its center and a glass having a low refractive index at its center to cause total reflection of light passing through the central glass. As a result, the structure is relatively simple, it is easy to transmit light in a desired path, and it is widely used in each field because it has the advantage of very little energy loss and little external influence during transmission.

In the present invention, after the light provided from the first light emitting portion 511a and the second light emitting portion 512a passes through the light emitting portion optical fibers 513a and 514a, the corresponding light receiving portion optical fibers 513b and 514b are respectively applied. Through the first light receiving unit 511b and the second light receiving unit 512b.

On the other hand, it is preferable that the light emitting part optical fibers 513a and 514a and the light receiving part optical fibers 513b and 514b have a certain degree of rigidity and wiring flexibility.

Installed in the sensor block XYZ stage 400 of the laser 600 for processing as a known technology for processing the workpiece (M) through the laser (LASER: Light Amplication by Stimulated Emission of Radiation), already widely known in the art Since it is a known technique used, a detailed description thereof will be omitted.

In the present exemplary embodiment, the sensor block XYZ stage 400 is illustrated as being installed on the upper end surface of the sensor block X-axis transfer frame 420, but the position may be freely changed as necessary. In addition, in the case of the processing laser 600 is shown as being fixed, but this is only one embodiment, it can be installed to be movable by applying a variety of known moving means, if necessary. Furthermore, in the case of the processing laser 600, it is preferable to install the processing laser 600 so that the laser LASER emitted from the processing laser 600 can be launched as close to the outer surface of the sensor block 500 as possible.

Next, the correlation between the components including the controller 700 will be described with reference to FIG. 5.

As illustrated in FIG. 5, the first light emitting unit 511a, the first light receiving unit 511b, the second light emitting unit 512a, and the second light receiving unit 512b constituting the runout sensor 510 may be processed. The runout motion of M) is measured (detected) and the measured value is transmitted to the controller 700. The controller 700 receives the measured value from the runout detection sensor 510 and calculates a correction value according to the runout displacement of the workpiece M through mutual comparison with a preset reference value. A first driving unit 110 installed on the rotating body Z-axis feeding frame 210, the rotating body X-axis feeding frame 220, and the rotating body Y-axis feeding frame 230 constituting the rotating body XYZ stage 200. The second driving unit 211 and the third driving unit 221 are individually operated to control the transfer of the rotating body Z-axis feed frame 210 and the rotating body X-axis feed frame 220 and the rotating body Y-axis feed frame 230 Through the workpiece (M) is to reposition the fixed to the rotating body (300). When the workpiece M is disposed at the normal position through the readjustment position of the rotating body 300, the control unit 700 operates the laser 600 for processing to process the workpiece M through the laser. Will be.

Referring to the operation relationship in the embodiment of the present invention made of such a configuration as follows.

As shown in FIG. 1, one end of the workpiece M is inserted into and fixed to the fixing part 320 of the rotating body 300, and the other end is installed to be disposed inside the sensor block 510. The state is as shown in FIG.

The micropores are formed in the circumferential surface along the longitudinal direction of the workpiece M through the laser of the processing laser 600 in the installed state as described above.

On the other hand, for the next micropore work is to rotate the rotating shaft 300 via the drive motor 310, at this time, as shown in Figure 6a, the workpiece (M) is the run-out detection sensor 510 is transmitting and receiving each other ), The light from the first light emitting portion 511a to the first light receiving portion 511b and the light from the second light emitting portion 512a to the second light receiving portion 512b of the runout of the workpiece M. The first light receiving unit 511b and the second light receiving unit 512b naturally receive only a little light while being partially blocked by the invasion, and thus the electrical signal is also changed. The electrical signal, that is, the measured value is transferred to the controller 700. Will print.

The controller 700 receives the measured value from the runout detection sensor 510 and calculates a correction value according to the runout displacement of the workpiece M through mutual comparison with a preset reference value. A first driving unit 110 installed on the rotating body Z-axis feeding frame 210, the rotating body X-axis feeding frame 220, and the rotating body Y-axis feeding frame 230 constituting the rotating body XYZ stage 200. The second driving unit 211 and the third driving unit 221 are individually operated to control the transfer of the rotating body Z-axis feed frame 210 and the rotating body X-axis feed frame 220 and the rotating body Y-axis feed frame 230 Through the workpiece (M) is to reposition the fixed to the rotating body (300).

Therefore, when the workpiece M is placed in the normal position as shown in FIG. 6B while the position of the rotating body 300 is readjusted, the control unit 700 operates to control the workpiece (600). The outer surface of M) is to be processed through a laser, and through the same method as described above, the outer surface of the workpiece M can be continuously and precisely processed.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

100: base 200: rotating body XYZ stage
210: rotating body Z-axis transfer frame 220: rotating body X-axis transfer frame
230: rotating body Y axis transfer frame 300: rotating body
400: sensor block XYZ stage 410: sensor block Z axis transport frame
420: X-axis transfer frame of sensor block 430: Y-axis transfer frame of sensor block
500: sensor block 510: runout detection sensor
511a: first light emitting unit 511b: first light receiving unit
512a: second light emitting unit 512b: second light emitting unit
513a.514a: light emitting part optical fiber 513b.514b: light receiving part optical fiber
600: laser for processing 700: control unit
M: Workpiece

Claims

Base:
Rotor body XYZ stage is installed on the upper surface of the base so as to be movable in the X, Y, Z axis direction, the operation control by the control unit:
A rotating body installed on the rotating body XYZ stage, the workpiece being fixed, and controlled by a control unit to rotate the workpiece about an axis;
Sensor block XYZ stage disposed on the opposite side of the rotating body XYZ stage and movable in the X, Y, Z-axis direction from the upper surface of the base: the outer surface of the workpiece protruding in the longitudinal direction installed on the sensor block XYZ stage Sensor block that measures the runout of the workpiece through the wrapped runout sensor and outputs the measured value:
A processing laser is installed on the sensor block XYZ stage, and is controlled by a control unit to process a workpiece through a laser.
The measured value is inputted from the runout detection sensor to calculate a correction value according to the runout displacement of the workpiece through mutual comparison with a preset reference value, and by operating the rotating body XYZ stage based on the correction value, the error according to the runout displacement is determined. Control unit to calibrate:
Runout detection sensor is installed in the sensor block,
A first light emitting unit and a first light receiving unit disposed to correspond to the first light emitting unit and receiving light provided from the first light emitting unit and converting the light into an electrical signal;
A second light emitting unit and a second light receiving unit which is disposed to correspond to the second light emitting unit and receives light provided from the first light emitting unit and converts the light into an electrical signal,
And the first light emitting unit and the first light receiving unit, the second light emitting unit, and the second light receiving unit are alternately disposed so as not to be in contact with each other.

The method of claim 1,
The sensor block XYZ stage is operation controlled by a control unit for adjusting the position of the sensor block position correction device for laser processing of a narrow tube.

The method of claim 1,
The light emitting part optical fiber and the light receiving part optical fiber are further provided on the first light emitting part and the second light emitting part and the first light receiving part and the second light receiving part.
After the light emitted from the first light emitting unit and the second light emitting unit passes through each light emitting unit optical fiber, it is irradiated to the first light receiving unit and the second light receiving unit through the corresponding light receiving unit optical fiber Position correction device for laser processing.

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