JP2018061985A - Press brake and bending angle detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press brake capable of detecting a bending angle of a work by using a two-dimensional laser displacement sensor.SOLUTION: A two-dimensional laser displacement sensor 30 comprises a laser beam emission part for irradiating a plurality of laser beams in a state arranged in a row to a work W bent by sandwiching a punch Tp and a die Td and a laser beam receiving part for receiving the laser beam reflected by the work W by two-dimensional beam receiving surface as displacement data. An angle arithmetic processing device 40 comprises a bending angle estimation part, a displacement data extraction part, and a bending angle calculation part. The bending angle estimation part determines an estimative bending angle of the work W. The displacement data extraction part extracts a plurality of displacement data included in a band area of a predetermined band width with a straight line corresponding to the estimative bending angle of the work W as the center among a plurality of displacement data received by the laser beam receiving part. The bending angle calculation part calculates the bending angle of the work W based on the plurality of extracted displacement data.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a press brake and a bending angle detection method for detecting a bending angle of a workpiece to be bent using a two-dimensional laser displacement sensor.

  A press brake for bending a workpiece, which is a metal plate material, includes an upper table on which a punch is mounted and a lower table on which a die is mounted. The press brake lowers the upper table to the lower table, and bends the work placed on the die between the punch and the die.

  The press brake includes a bending angle detection device including an angle sensor in order to detect whether the workpiece is bent at a target angle. For example, as an angle sensor, a laser type angle sensor having a laser light emitting unit that emits a linear laser beam and an imaging unit that images a workpiece irradiated with the laser beam is often used (see Patent Document 1). ).

JP 2000-18931 A

  In various fields, a two-dimensional laser displacement sensor for measuring the shape of an object is used. The two-dimensional laser displacement sensor irradiates an object with a plurality of laser beams and receives the laser beam reflected from the object with an image sensor. Since the way of reflecting the laser beam differs depending on the shape of the object, the position of the pixel that receives the laser beam in the image sensor changes. A two-dimensional laser displacement sensor measures the shape of an object based on the position of a pixel that receives laser light.

  It is conceivable to use a two-dimensional laser displacement sensor for a press brake bending angle detection device. When the workpiece is irradiated with a plurality of laser beams emitted from the two-dimensional laser displacement sensor and the bending angle of the workpiece is detected based on the laser beam (displacement data) reflected from the workpiece, the following problem should be solved. There are challenges.

  Since the image sensor receives laser light due to multiple reflections, the displacement data includes incorrect data that cannot be used to detect the bending angle. In addition, the position of the image sensor that receives the reflected laser light varies due to the influence of the workpiece material, disturbance light, etc., so that the displacement data is not arranged in a straight line but is distributed with a predetermined width. . As described above, when the two-dimensional laser displacement sensor is used to detect the bending angle of the workpiece, the bending angle of the workpiece is determined based on the displacement data including the incorrect data and distributed with a predetermined width. We must solve the problem of what to ask for.

  An object of the present invention is to solve such problems and to provide a press brake and a bending angle detection method capable of detecting a bending angle of a workpiece using a two-dimensional laser displacement sensor.

  In the present invention, an upper table for holding a punch, a lower table for holding a die, and a work bent between the punch and the die are arranged with a plurality of laser beams in a line. A two-dimensional laser displacement sensor having a laser light-emitting unit that emits light, a laser light-receiving unit that receives laser light reflected from the workpiece as displacement data on a two-dimensional light-receiving surface, and a plurality of displacements received by the laser light-receiving unit An angle calculation processing device that detects a bending angle of the workpiece based on the data, and the angle calculation processing device estimates a bending angle of the workpiece at each time to obtain an estimated bending angle. And at each time, out of a plurality of two-dimensionally distributed displacement data received by the laser receiving unit, a straight line corresponding to the estimated bending angle of the workpiece is the center. A displacement data extraction unit for extracting a plurality of displacement data included in a band region having a predetermined bandwidth, and a bending angle of the workpiece based on the plurality of displacement data extracted by the displacement data extraction unit at each time. There is provided a press brake including a bending angle calculation unit for calculating.

  Further, the present invention irradiates a workpiece bent between a punch and a die with a plurality of laser beams emitted from a laser emission unit in a two-dimensional laser displacement sensor and arranged in a line. The reflected laser light is received as displacement data by the two-dimensional light receiving surface of the laser light receiving unit in the two-dimensional laser displacement sensor, and the computer equipment estimates the bending angle of the workpiece at each time to determine the estimated bending angle. A predetermined bandwidth centered on a straight line corresponding to the estimated bending angle of the workpiece among a plurality of two-dimensionally distributed displacement data received by the laser light receiving unit at each time. The plurality of displacement data included in the band region is extracted, and the computer device, at each time, extracts the plurality of displacement data included in the band region. Based on the data, to provide a bending angle detecting method and calculates a bending angle of the workpiece.

  According to the press brake and the bending angle detection method of the present invention, the bending angle of a workpiece can be detected using a two-dimensional laser displacement sensor.

1 is a perspective view illustrating a schematic overall configuration of a press brake according to an embodiment. It is a perspective view which shows the state which the two-dimensional laser displacement sensor is irradiating the die | dye and the workpiece | work with a laser beam. It is a side view which shows the state which the two-dimensional laser displacement sensor is irradiating the die | dye and the workpiece | work with a laser beam. It is a figure which shows the displacement data distributed in the two-dimensional form which the laser light-receiving part of the two-dimensional laser displacement sensor received. It is a block diagram which shows the functional internal structural example of the angle arithmetic processing apparatus with which the press brake of one Embodiment is provided. It is a figure which shows the xz coordinate set when a two-dimensional laser displacement sensor irradiates a laser beam to a die | dye and a workpiece | work, and receives the reflected laser beam. It is a figure which shows a measurement area | region in order to measure the angle of the workpiece | work set to xz coordinate. It is a figure which shows the band area | region set to a measurement area | region. It is a figure for demonstrating the specific setting method of a band area | region. It is a figure which shows the displacement data contained in a band area | region. It is a flowchart which shows the operation | movement performed by the operation | movement of the press brake of one Embodiment, and the bending angle detection method of one Embodiment.

  Hereinafter, a press brake and a bending angle detection method according to an embodiment will be described with reference to the accompanying drawings. First, a schematic configuration of a press brake according to an embodiment will be described with reference to FIG.

  As shown in FIG. 1, the press brake includes an upper table 10 and a lower table 20. The upper table 10 is configured to move up and down by hydraulic cylinders 11L and 11R provided on the left and right. An upper mold holder 12 is attached to the upper table 10, and a lower mold holder 22 is attached to the lower table 20. A punch Tp is mounted on the upper mold holder 12, and a die Td is mounted on the lower mold holder 22.

  The workpiece W, which is a metal plate material, is disposed on the die Td. When the upper table 10 is lowered, the work W is sandwiched and bent by the punch Tp and the die Td. FIG. 1 shows a state in which the bending of the workpiece W is completed and the upper table 10 is raised.

  A two-dimensional laser displacement sensor 30 is mounted on the front side of the lower table 20. In FIG. 1, the two-dimensional laser displacement sensor 30 is mounted on the back side of the lower table 20 so as to face the two-dimensional laser displacement sensor 30 on the near side, although it is hidden behind the die Td. For example, an inline profile measuring instrument LJ-V7000S series sold by Keyence Corporation can be used as the two-dimensional laser displacement sensor 30.

  The pair of two-dimensional laser displacement sensors 30 is movable along rails 23 provided in the lower table 20 and extending in the left-right direction. The pair of two-dimensional laser displacement sensors 30 are positioned so as to sandwich the die Td held by the lower mold holder 22 from the front-rear direction.

  As shown in FIG. 2, the two-dimensional laser displacement sensor 30 generally includes a laser light emitting unit 31 that irradiates a die Td and a workpiece W with a plurality of laser beams arranged in a line, and a die Td or And a laser receiving unit 32 that receives the laser beam reflected by the workpiece W. The laser light emitting unit 31 irradiates a line of laser light at an angle inclined with respect to the side surface of the die Td. The laser light receiving unit 32 includes a condensing lens 321 that condenses laser light and an image sensor 322 having a two-dimensional laser light receiving surface. The imaging element 322 is, for example, a CMOS (Complementary Metal Oxide Semiconductor).

  As shown in FIG. 3, when the two-dimensional laser displacement sensor 30, the die Td and the workpiece W are viewed from the side, the x-axis in the width direction and the distance direction from the two-dimensional laser displacement sensor 30 to the die Td or the workpiece W are shown. A two-dimensional region with a certain z-axis is a region for detecting a change in shape due to laser light. The direction of one side of the rectangular imaging element 322 is the x-axis.

  FIG. 4 shows an example of a state in which the image sensor 322 receives laser light reflected by the die Td or the workpiece W as displacement data. The y axis in FIG. 4 is the direction of one side orthogonal to the x axis of the image sensor 322. In FIG. 4, a region 3221 is a region that receives the laser light reflected by the die Td, and a region 3222 is a region that receives the laser light reflected by the workpiece W. A region 3220 is a region receiving laser light by multiple reflection. As will be described later, when the region 3222 is regarded as a line having a predetermined width, the inclination of the region 3222 in the xy coordinates indicates the angle of the workpiece W.

  One point in each of the regions 3220 to 3222 indicates a position where displacement data (laser light) is received. Regions 3221 and 3222 are a set of positions at which the displacement data reflected by one surface of the die Td and the workpiece W are received, respectively, and the positions at which the light is received due to the influence of the material of the workpiece W or ambient light vary, so They are distributed in a predetermined width. Since the region 3220 is a region that receives laser light by multiple reflection, the displacement data of the region 3220 is incorrect data.

  The displacement data shown in FIG. 4 is supplied to the angle calculation processing device 40 shown in FIG. The angle calculation processing device 40 can be configured by computer equipment. The NC device 50 controls the entire press brake. Various information necessary for detecting the bending angle of the workpiece W is input from the NC device 50 to the angle calculation processing device 40. The angle calculation processing device 40 detects the bending angle of the workpiece W and supplies information indicating the detected bending angle of the workpiece W to the NC device 50. The NC device 50 controls the bending of the workpiece W according to the input bending angle of the workpiece W.

  An operation pendant 60 having a display unit 61 and an operation unit 62 is connected to the NC device 50.

  As illustrated in FIG. 5, the angle calculation processing device 40 includes a bending angle estimation unit 401, a displacement data extraction unit 402, and a bending angle calculation unit 403 as functional internal configurations. The bending angle estimation unit 401 is supplied with material information (plate thickness information and metal type information) of the workpiece W and a descending amount (so-called D value) of the upper table 10 from the NC device 50. Depending on the material of the workpiece W, it can be estimated based on plastic working theory how much the upper table 10 is lowered after the punch Tp contacts the workpiece W and how much the workpiece W is bent. The bending angle estimation unit 401 estimates the bending angle of the workpiece W and supplies the estimated bending angle to the displacement data extraction unit 402.

  In order to improve the accuracy of the bending angle estimation by the bending angle estimation unit 401, data other than the material information of the workpiece W and the lowering amount of the upper table 10 may be supplied to the bending angle estimation unit 401.

  The displacement data extraction unit 402 is supplied with the displacement data shown in FIG. 4 from the two-dimensional laser displacement sensor 30. The displacement data extraction unit 402 is supplied with values of x1 and xN and a bandwidth ε described later from the NC device 50. The values of x1 and xN and the bandwidth ε are preset in the NC device 50 by the operator operating the operation unit 62. The displacement data extraction unit 402 extracts displacement data of a portion necessary for detecting the bending angle of the workpiece W from the displacement data shown in FIG. The extracted displacement data is supplied to the bending angle calculation unit 403.

  The bending angle calculation unit 403 calculates the bending angle of the workpiece W based on the extracted displacement data. The bending angle calculation unit 403 is supplied with a threshold value Th described later from the NC device 50. The bending angle calculation unit 403 may use the threshold Th when executing the process of calculating the bending angle of the workpiece W.

  Hereinafter, how the angle calculation processing device 40 detects the bending angle of the workpiece W will be described. As shown in FIG. 6, the angle calculation processing device 40 sets the xz coordinate by setting z = 0 on the surface (laser light receiving surface) of the image sensor 322 and x = 0 on the shoulder of the die Td. Since the information about the die Td being used is supplied from the NC device 50 to the angle calculation processing device 40 and the position of z = 0 is set in advance, the angle calculation processing device 40 has (x, z) = 0 can be set.

  6 to 9 show a state in which the die Td and the workpiece W are inclined so that the x-axis is horizontal. 6 and 7, the hatched region irradiates the laser beam from the laser emitting unit 31 to the die Td or the workpiece W, and the laser receiving unit 32 receives the laser beam reflected by the die Td or the workpiece W. Indicates the area. 8 and 9, the hatching shown in FIGS. 6 and 7 is omitted.

  As shown in FIG. 7, the displacement data extraction unit 402 measures from the position x1 to the position xN for measuring the angle of the workpiece W based on the x-axis positions x1 and xN input by the operator through the operation unit 62. Region Rw is set. As shown in FIG. 8, the displacement data extraction unit 402 sets a band region V having a band width ε on the upper surface side and the lower surface side of the workpiece W in the measurement region Rw. The width 2ε of the band region V extending over the upper surface side and the lower surface side of the work W corresponds to the width 2ε in the y-axis direction in the xy coordinates, as will be described later.

  The displacement data shown in FIG. 4 corresponds to a state in which the state of the laser light irradiated onto the die Td or the workpiece W is projected onto the laser light receiving surface of the image sensor 322. Accordingly, the band region V is a region corresponding to a part of the region 3222.

  In FIG. 9, the angle formed between the die Td and the z-axis is γ. The angle γ is known. The distance from the shoulder A (0, z0) of the die Td to the corner D of the end of the V-shaped recess and the upper surface is defined as a. The workpiece W is in contact with the corner portion D. A position of the workpiece W at an arbitrary position xi in the measurement region Rw from the position x1 to the position xN is defined as B. Let E be the intersection of a line parallel to the z-axis passing through the corner D and a line parallel to the x-axis passing through the position B. An estimated bending angle of the workpiece W at an arbitrary time t is defined as θ (t). Let the angle BDA be φ (θ (t)).

  The band region V (x, z) in x = xi (x1 ≦ xi ≦ xN) can be expressed by Equation (1) using the estimated bending angle θ (t). ZB in Formula (1) is represented by Formula (2). Since z is a function of the estimated bending angle θ (t) and the band width ε, the band region V (x, z) is strictly the band region V (x, z (θ (t), ε)). It is represented by The band region V (x, z) or V (x, z (θ (t), ε)) may be abbreviated as the band region V in some cases.

  As described above, the displacement data extraction unit 402 sets the band region V (x, z). The displacement data extraction unit 402 includes a straight line Lθ (t) corresponding to the estimated bending angle θ (t) as shown in FIG. 10 among the displacement data of the region 3222 receiving the laser light reflected by the workpiece W in FIG. ) To extract displacement data included in the width of 2ε.

  The bending angle calculation unit 403 calculates the angle of the straight line by the least square method using the displacement data included in the band region V (x, z). The angle of the straight line calculated by the bending angle calculation unit 403 indicates the bending angle of the workpiece W.

  If the ratio obtained by dividing the number of displacement data included in the band region V (x, z) by the number of all displacement data in the measurement region Rw is larger than the threshold value Th, the displacement data is in the band region V (x, z). The displacement data accurately indicates the bending angle of the workpiece W. However, if the ratio is equal to or less than the threshold Th, the displacement data is not concentrated in the band region V (x, z), and does not accurately indicate the bending angle of the workpiece W.

  Therefore, it is preferable that the bending angle calculation unit 403 determines whether or not the bending angle of the workpiece W can be accurately detected based on whether or not the above ratio is larger than the threshold value Th. It is preferable that the bending angle calculation unit 403 calculates the bending angle of the workpiece W by the least square method only when the bending angle of the workpiece W can be accurately detected.

  With reference to FIG. 11, the operation of the angle calculation processing device 40 and the process executed by the bending angle detection method of the present embodiment will be described again. The NC device 50 holds a parameter table in which the bandwidth ε and the threshold Th are set according to the material information of the workpiece W. In FIG. 11, the angle calculation processing device 40 (the displacement data extraction unit 402 or the bending angle calculation unit 403) acquires the bandwidth ε and the threshold value Th from the parameter table based on the material information of the workpiece W in step S1. .

  In step S2, the angle calculation processing device 40 (bending angle estimation unit 401) estimates the bending angle θ (t) at the current time based on the plastic working theory. In step S3, the angle calculation processing device 40 (displacement data extraction unit 402) calculates the band region V by using the positions x1, xN, the estimated bending angle θ (t), and the band width ε.

  The angle calculation processing device 40 (displacement data extraction unit 402) extracts displacement data of each of the measurement region Rw and the band region V in step S4. The angle calculation processing device 40 (displacement data extraction unit 402) counts the number Nw of displacement data included in the measurement region Rw and the number Nv of displacement data included in the band region V in step S5. The displacement data and the data numbers Nw and Nv included in the band region V are supplied to the bending angle calculation unit 403.

  In step S6, the angle calculation processing device 40 (bending angle calculation unit 403) determines whether (Nv / Nw) is larger than the threshold value Th. If (Nv / Nw) is larger than the threshold value Th (YES), the angle calculation processing device 40 (bending angle calculation unit 403) uses the displacement data included in the band region V in step S7 by the least square method. The angle of the straight line is calculated and stored as the angle α (t) of the workpiece W at the current time, and the process proceeds to step S8.

  If (Nv / Nw) is not greater than the threshold Th (NO), the angle calculation processing device 40 (bending angle calculation unit 403) determines that the angle α (t) of the workpiece W at the current time is not detected in step S12. Then, the process proceeds to step S8.

  In step S8, the angle calculation processing device 40 (bending angle calculation unit 403) calculates an average angle αave (t) from the angle α (t) of the workpiece W at the current time and the stored past angle α. calculate. The past angle α may be the angle α (t−1) calculated immediately before the current time, or the angle α (t−1) calculated immediately before and the angle α (t−2) calculated immediately before. The angle α at a plurality of times including the angle α (t−1) calculated immediately before may be used. The angle calculation processing device 40 (bending angle calculation unit 403) outputs the average angle αave (t) as the bending angle of the workpiece W in step S9.

  By setting the average angle αave as the bending angle of the workpiece W, the detected bending angle of the workpiece W is stabilized. The angle calculation processing device 40 (bending angle calculation unit 403) may obtain an average angle αave of the angles α at a plurality of times within 0.2 seconds.

  In step S10, the angle calculation processing device 40 determines whether or not the workpiece W has been bent to the target angle. If the workpiece W is not bent to the target angle (NO), the angle calculation processing device 40 determines whether or not the next measurement time (t + 1) for detecting the bending angle of the workpiece W is reached in step S11. . If the next measurement time (t + 1) is not reached (NO), step S11 is repeated until the next measurement time (t + 1) is reached. If the next measurement time (t + 1) is reached (YES), the next measurement time (t + 1) is set as the current time t, and the processes from step S2 to S11 are repeated.

  If the workpiece W is bent to the target angle in step S10 (YES), the angle calculation processing device 40 ends the detection processing of the bending angle of the workpiece W.

  As described above, according to the press brake and the bending angle detection method of the present embodiment, the bending angle of the workpiece W can be detected using the two-dimensional laser displacement sensor.

  The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the present invention. In the configuration shown in FIG. 1, the angle calculation processing device 40 separate from the NC device 50 detects the bending angle of the workpiece W, but the NC device 50 may have the function of the angle calculation processing device 40. . The NC device 50 may include the bending angle estimation unit 401 in FIG. Any computer device may be configured as the angle calculation processing device 40.

DESCRIPTION OF SYMBOLS 10 Upper table 20 Lower table 30 Two-dimensional laser displacement sensor 31 Laser light emission part 32 Laser light-receiving part 40 Angle calculation processing apparatus 50 NC apparatus 401 Bending angle estimation part 402 Displacement data extraction part 403 Bending angle calculation part Td Die Tp Punch W Workpiece

Claims (6)

An upper table to hold the punch,
A lower table to hold the die,
A laser light emitting unit for irradiating a workpiece bent between the punch and the die in a state where a plurality of laser beams are arranged in a line, and a two-dimensional light receiving surface using the laser light reflected by the workpiece as displacement data A two-dimensional laser displacement sensor having a laser light receiving portion that receives light at
An angle calculation processing device for detecting a bending angle of the workpiece based on a plurality of displacement data received by the laser light receiving unit;
With
The angle calculation processing device includes:
A bending angle estimator for estimating the bending angle of the workpiece at each time and obtaining an estimated bending angle;
Among a plurality of two-dimensionally distributed displacement data received by the laser receiving unit at each time, a plurality of displacement data included in a band region having a predetermined bandwidth centered on a straight line corresponding to the estimated bending angle of the workpiece A displacement data extraction unit for extracting displacement data of
At each time, based on a plurality of displacement data extracted by the displacement data extraction unit, a bending angle calculation unit that calculates a bending angle of the workpiece,
A press brake characterized by comprising:   The bending angle calculation unit calculates a bending angle of the workpiece by calculating an angle of a straight line of a region where a plurality of displacement data extracted by the displacement data extraction unit is distributed on the light receiving surface by a least square method. The press brake according to claim 1, wherein the press brake is characterized in that: The direction of one side of the light receiving surface is the x axis,
The displacement data extraction unit counts a first data number of displacement data included in the measurement region using a range from the first position to the second position on the x-axis as a measurement region, and Count the second number of displacement data included in the band area,
When the ratio of the second data number divided by the first data number is greater than a predetermined threshold, the bending angle calculation unit calculates the bending angle of the workpiece based on a plurality of displacement data included in the band region. The press brake according to claim 1, wherein the press brake is calculated. The workpiece bent between the punch and the die is irradiated with a plurality of laser beams emitted from the laser light emitting unit of the two-dimensional laser displacement sensor and arranged in a line.
The laser beam reflected by the workpiece is received as displacement data on the two-dimensional light receiving surface of the laser receiving unit in the two-dimensional laser displacement sensor,
The computer equipment calculates the estimated bending angle by estimating the bending angle of the workpiece at each time,
A band having a predetermined bandwidth centered on a straight line corresponding to the estimated bending angle of the workpiece, out of a plurality of two-dimensionally distributed displacement data received by the laser receiver at each time. Extract multiple displacement data included in the area,
The bending angle detection method, wherein the computer device calculates a bending angle of the workpiece based on a plurality of displacement data included in the band region at each time.   The computer apparatus calculates a bending angle of the workpiece by calculating an angle of a straight line of a region where a plurality of extracted displacement data is distributed on the light receiving surface by a least square method. Bending angle detection method. The direction of one side of the light receiving surface is the x axis,
The computer device counts a first data number of displacement data included in the measurement area with a range from a first position to a second position on the x-axis as a measurement area;
The computer device counts a second data number of displacement data included in the band region in the measurement region;
The computer device calculates a bending angle of the workpiece based on a plurality of displacement data included in the band region when a ratio of the second data number divided by the first data number is larger than a predetermined threshold value. The bending angle detection method according to claim 4 or 5, wherein:

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