Position detection device, galvanometer assembly and metal 3D printing equipment

Abstract

The invention relates to the technical field of detection, aims to solve the problem that a galvanometer position detection scheme in the prior art is insufficient in precision and stability, and provides a position detection device, a galvanometer assembly and metal 3D printing equipment. The position detection device comprises a rotating piece and a position sensitive sensor. The rotating sheet is connected to a galvanometer motor and is used for rotating under the driving of the galvanometer motor; a light-transmitting area is arranged on the rotating piece, and the light-transmitting area is in a strip shape extending along an arc line. The position sensitive sensor is opposite to the rotating sheet along the axial direction of the galvanometer motor; the position sensitive sensor is provided with a photosensitive area, and the photosensitive area is in a strip shape extending in the radial direction of the rotating piece. The intersection point position of the projection of the light-transmitting area on the plane where the photosensitive area is located and the photosensitive area corresponds to the rotating angle of the rotating piece. The beneficial effects are that the angle position detection precision of the galvanometer is high and the stability of the detection result is good.

Description

Technical Field

[0001] The present application relates to the field of detection technology, and in particular to a position detection device, a galvanometer assembly and a metal 3D printing device. Background Art

[0002] For example, SLM printing equipment or other laser systems use galvanometers. To measure the rotation angle (or rotational position) of the galvanometer, some solutions use a PD position detector, with a butterfly plate installed on the rotor shaft of the galvanometer motor. When the rotor rotates, the butterfly plate will cover or expose a part of the photocell. The photocell will generate two microampere currents, which will be sent back to the servo control board, and then the servo control board will convert the current into voltage to determine the rotational position of the rotor. Combined with the rest of the control loop, it can ensure that the galvanometer operates accurately and stably while complying with the commands provided by the servo control board.

[0003] However, this solution has the following obvious disadvantages: first, the current output by the photocell is proportional to the luminous intensity of the LED lamp. The size of the photocell current directly affects the output parameters of the galvanometer, and the LED is a device that will attenuate, which in turn affects the stability of the measurement results; second, the photocell can only output a maximum current of about 2 microamperes, which can easily generate noise signals and cause the entire unit to fail completely; third, multiple photocells are installed separately, and the movement caused by thermal expansion may introduce unnecessary proportional drift into the system, affecting the measurement accuracy. Summary of the invention

[0004] The present application provides a position detection device, a galvanometer assembly and a metal 3D printing device to solve the problem of insufficient accuracy and stability of the galvanometer position detection solution in the known technology.

[0005] In a first aspect, the present application provides a position detection device, comprising a rotating plate and a position sensitive sensor. The rotating plate is connected to a galvanometer motor and is used to rotate under the drive of the galvanometer motor; a light-transmitting area is provided on the rotating plate, and the light-transmitting area is in the shape of a strip extending along an arc. The position sensitive sensor is opposite to the rotating plate along the axial direction of the galvanometer motor; the position sensitive sensor has a photosensitive area, and the photosensitive area is in the shape of a strip extending along the radial direction of the rotating plate; the intersection position of the projection of the light-transmitting area on the plane where the photosensitive area is located and the photosensitive area corresponds to the rotation angle of the rotating plate.

[0006] In a possible implementation, the position detection device further includes a light source, which corresponds to a light-transmitting area along the axis of the rotating plate. Light emitted by the light source can pass through the light-transmitting area and then illuminate the photosensitive area, forming a light spot having a shape corresponding to the shape of the light-transmitting area.

[0007] In a possible implementation, the polar coordinate equation of the arc in the polar coordinates with the rotation center point of the rotating piece as the pole is r=aθ+b, wherein a and b are constants, a is not equal to 0, θ is the polar angle, r is the polar diameter, and the difference between the polar angles of the starting point and the end point of the arc is less than 2π;

[0008] The rotation angle θ of the rotating piece is calculated by formula 1 and formula 2:

[0009] (I2-I1) / (I2+I1)=2x / LFormula 1

[0010] θ=(r0+x+b) / a;Formula 2

[0011] In formula 1, x is the distance between the irradiated position of the photosensitive area and the center position of the photosensitive area, L is the length of the photosensitive area, I1 is the photocurrent on one side of the position sensitive sensor, and I2 is the photocurrent on the other side of the position sensitive sensor;

[0012] In formula 2, r0 is the distance from the center of the photosensitive area to the pole of the polar coordinates.

[0013] In a possible implementation, the rotating sheet is made of an opaque material, and the light-transmitting area is an arc-shaped groove opened on the rotating sheet, and the arc-shaped groove penetrates the rotating sheet along the thickness direction.

[0014] In a possible implementation, the rotating plate includes a connecting portion and a rotating plate, the connecting portion is provided with a central hole for fixedly connecting to a rotating shaft of a galvanometer motor, the rotating plate is connected to the connecting portion, and the light-transmitting area is provided on the rotating plate.

[0015] In a possible implementation, the position detection device further includes a mounting plate having a through hole, through which the rotating shaft of the galvanometer motor passes and is connected to the rotating plate; the position sensitive sensor is connected to a side of the mounting plate facing the rotating plate.

[0016] In a possible implementation, the position sensitive sensor is mounted on a surface of the end cap of the galvanometer motor that faces the rotating piece.

[0017] In a second aspect, the present application provides a galvanometer assembly, including a reflector, the aforementioned position detection device, and a galvanometer motor. The galvanometer motor includes a housing and a rotating shaft, one end of the rotating shaft is connected to the reflector, and the other end is connected to a rotating plate; the position sensitive sensor is located between the galvanometer motor and the rotating plate and is fixed relative to the housing.

[0018] In a possible implementation, the galvanometer assembly further includes a controller, which is electrically connected to the position detection device and the galvanometer motor and is used to control the movement of the galvanometer motor according to the rotation angle information detected by the position detection device.

[0019] In a third aspect, the present application provides a metal 3D printing device, comprising the aforementioned galvanometer assembly.

[0020] In a fourth aspect, the present application provides a galvanometer control method based on the aforementioned galvanometer assembly; the galvanometer control method comprises:

[0021] The rotation angle information of the rotating piece is obtained through the position detection device, and the galvanometer motor is controlled to rotate to a desired angle according to the rotation angle information.

[0022] The position detection device, galvanometer assembly and metal 3D printing equipment in the present application, by setting a rotating piece with a light-transmitting area with a set arc combined with the photoelectric effect of the position sensitive sensor, the detection result is independent of the luminous intensity and shape of the light source, but only related to the position of the light source on the photosensitive area. The current output by the position sensitive sensor used can reach the nanoampere level, which can better suppress noise interference, and the detection result is stable and highly accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A three-dimensional view of a galvanometer assembly according to an embodiment of the present application;

[0025] Figure 2 for Figure 1 A front view of the galvanometer assembly;

[0026] Figure 3 for Figure 1 A side view of a part of the structure;

[0027] Figure 4 for Figure 3 Another state view of ;

[0028] Figure 5 for Figure 3 Another state view of

[0029] Figure 6 This is a three-dimensional view of the metal 3D printing device according to an embodiment of the present application.

[0030] Description of main component symbols:

[0031] Galvanometer assembly 10

[0032] Galvanometer motor 11

[0033] Reflector 12

[0034] Position detection device 13

[0035] Case 14

[0036] Shaft 15

[0037] Light source 16

[0038] Rotating piece 17

[0039] Position sensitive sensor 18

[0040] Controller 19

[0041] Mounting plate 20

[0042] Via 21

[0043] Light absorbing surface 22

[0044] Light transmission area 23

[0045] Arc 24

[0046] Photosensitive area 25

[0047] Intersection 26, 26a, 26b

[0048] Arc groove 27

[0049] Connection part 28

[0050] Transfer 29

[0051] Center hole 30

[0052] Starting point 31

[0053] End 32

[0054] Metal 3D printing equipment 100

[0055] Laser 80

[0056] Printing surface 200 DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0058] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may also be a centered element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may also be a centered element. When an element is considered to be "set on" another element, it may be directly set on the other element or there may also be a centered element. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "or / and" used herein includes any and all combinations of one or more related listed items.

[0060] Some embodiments of the present application are described in detail. In the absence of conflict, the following embodiments and features of the embodiments can be combined with each other.

[0061] Example

[0062] See also Figure 1 and Figure 2 This embodiment provides a galvanometer assembly 10, including a galvanometer motor 11, a reflector 12 and a position detection device 13.

[0063] The galvanometer motor 11 includes a housing 14 and a rotating shaft 15 , wherein the rotating shaft 15 may be a rotor shaft of the galvanometer motor 11 .

[0064] The position detection device 13 includes a light source 16 , a rotating plate 17 and a position sensitive sensor 18 (PSD, Position Sensitive Detector).

[0065] In this embodiment, one end of the rotating shaft 15 of the galvanometer motor 11 is connected to the reflector 12, and the other end extends from the rear end of the housing 14 and is connected to the rotating piece 17. In this way, the galvanometer motor 11 drives the reflector 12 to rotate while also driving the rotating piece 17 to rotate. In some embodiments, the rotation angle of the rotating piece 17 is equal to the rotation angle of the reflector 12, and the rotating piece 17 and the reflector 12 rotate synchronously, that is, the rotation angle of the rotating piece 17 can reflect the rotation angle of the reflector 12 in real time.

[0066] In this embodiment, the galvanometer assembly 10 further includes a controller 19 , which is electrically connected to the position detection device 13 and the galvanometer motor 11 , and is used to control the movement of the galvanometer motor 11 according to the rotation angle information detected by the position detection device 13 .

[0067] The position sensitive sensor 18 is located between the galvanometer motor 11 and the rotating plate 17 and is fixed relative to the housing 14. For example, as shown in the figure, the position sensitive sensor 18 is fixed on a mounting plate 20, and the mounting plate 20 is provided with a through hole 21. The rotating shaft 15 of the galvanometer motor 11 passes through the through hole 21 and is connected to the rotating plate 17. The position sensitive sensor 18 is connected to the side of the mounting plate 20 facing the rotating plate 17. There is a gap between the rotating shaft 15 of the galvanometer motor 11 and the through hole 21, so that the rotating shaft 15 will not drive the mounting plate 20 to rotate. The mounting plate 20 can be directly connected to the galvanometer motor 11, or it can be isolated from the galvanometer motor 11 and independently fixed and installed to reduce the vibration of the galvanometer motor 11 during operation and affect the detection accuracy of the position sensitive sensor 18.

[0068] Optionally, the surface of the mounting plate 20 facing the rotating plate 17 is set as a light-absorbing surface 22 to absorb the light irradiated thereon, thereby preventing the light reflected from the surface from being reflected again by the rotating plate 17 and irradiating the position sensitive sensor 18, thereby generating a noise signal and affecting the detection accuracy of the position sensitive sensor 18.

[0069] In other embodiments, the aforementioned mounting plate 20 may be eliminated, and the position sensitive sensor 18 may be directly mounted on the surface of the end cap of the galvanometer motor 11 facing the rotating piece 17 to reduce the number of parts.

[0070] In this embodiment, the rotating piece 17 is connected to the galvanometer motor 11 and is used to rotate under the drive of the galvanometer motor 11. The rotating piece 17 is provided with a light-transmitting area 23, which is in the shape of a strip extending along an arc 24. The position sensitive sensor 18 is opposite to the rotating piece 17 along the axial direction of the galvanometer motor 11, and the position sensitive sensor 18 has a photosensitive area 25, which is in the shape of a strip extending along the radial direction of the rotating piece 17. The position of the intersection 26 of the projection of the light-transmitting area 23 on the plane where the photosensitive area 25 is located and the photosensitive area 25 corresponds to the rotation angle of the rotating piece 17.

[0071] The light source 16 corresponds to the light-transmitting area 23 along the axial direction of the rotating piece 17. The light emitted by the light source 16 can pass through the light-transmitting area 23 and then illuminate the photosensitive area 25, forming a light spot with a shape corresponding to the shape of the light-transmitting area 23. For the aforementioned arc-shaped light-transmitting area 23, the light spot formed is also arc-shaped. The arc-shaped light spot intersects with the photosensitive area 25 of the position sensitive sensor 18. The photosensitive area 25 is illuminated at the intersection 26 to generate a photoelectric signal. By analyzing the photoelectric signal, the position where the photosensitive area 25 is illuminated can be obtained, and then the rotation angle of the rotating piece 17 can be obtained through the corresponding relationship between the position and the rotation angle of the rotating piece 17, and then the rotation angle of the galvanometer motor 11 and the reflector 12 can be obtained.

[0072] In this embodiment, the rotating piece 17 can be made of an opaque material, and the light-transmitting area 23 is an arc groove 27 provided on the rotating piece 17, and the arc groove 27 penetrates the rotating piece 17 along the thickness direction. In this way, the light emitted by the light source 16 is blocked by the rotating piece 17, and only the light corresponding to the position of the arc groove 27 can pass through.

[0073] Optionally, the width of the arc groove 27 is set to be smaller, so that the arc groove 27 is roughly an arc-shaped thin line, so that the transmitted light spot is also an arc-shaped thin line, which is conducive to improving the position accuracy obtained. Therefore, the solution can be used to conveniently obtain the required position accuracy by setting the arc groove 27 with a suitable width, and then obtain the angle information of the reflector 12 with the required accuracy.

[0074] Of course, when the width of the arc groove 27 is relatively large, accurate position information can also be obtained through certain analytical algorithms or pre-simulations.

[0075] In other embodiments, the light-transmitting area 23 may not be grooved, but may be made of a light-transmitting material. For example, the rotating piece 17 is made of a transparent material (such as light-transmitting glass), and the area other than the light-transmitting area 23 is treated to be opaque (such as covered with a light-shielding layer). In this way, the rotating piece 17 allows light to pass only in the light-transmitting area 23.

[0076] In this embodiment, optionally, the rotating piece 17 includes a connecting portion 28 and a rotating piece 29, the connecting portion 28 is provided with a central hole 30 for being fixedly connected to the rotating shaft 15 of the galvanometer motor 11, the rotating piece 29 is connected to the connecting portion 28, and the light-transmitting area 23 is provided on the rotating piece 29. In this solution, the connecting portion 28 can be set thicker to ensure reliable connection with the galvanometer motor 11, and the rotating piece 29 can be set thinner to facilitate the light emitted by the light source 16 to pass through.

[0077] Optionally, the rotating plate 29 can be roughly arranged in a sector shape, as long as it can allow the layout of the light-transmitting area 23. The rotating plate 29 can be made of opaque glass or other materials. The rotating plate 29 should have a certain structural rigidity to avoid excessive deformation affecting the shape and position of the light-transmitting area 23, thereby reducing the accuracy of position detection.

[0078] In this embodiment, the light source 16 may be a linear light source, and its irradiation area corresponds to the photosensitive area 25 ; the light source 16 may also be a surface light source, and its irradiation area at least covers the photosensitive area 25 .

[0079] The arc 24 of the light-transmitting area 23 conforms to a certain curve equation to ensure that the rotation angle of the rotating plate 17 and the position of the light passing through the light-transmitting area 23 irradiating the photosensitive area 25 are in a corresponding relationship. Figure 2 An implementation method is given.

[0080] See also Figure 3In this embodiment, the polar coordinate equation of the arc 24 of the light-transmitting area 23 in the polar coordinates with the rotation center point of the rotating plate 17 (located on the rotation axis of the galvanometer motor 11) as the pole O1 is r=aθ+b, wherein a and b are constants, and a is not equal to 0, θ is the polar angle, r is the polar diameter, and the difference between the polar angles of the starting point 31 and the end point 32 of the arc 24 is less than 2π. In actual use, the difference between the polar angles of the starting point 31 and the end point 32 of the arc 24 only needs to be no less than the rotation angle range of the galvanometer motor 11 and the reflector 12. For example, the rotation range of the galvanometer motor 11 and the reflector 12 in use is 30°, then the difference between the polar angles of the starting point 31 and the end point 32 of the arc 24 only needs to be no less than 30°, for example, set to 35°. To fully utilize the photosensitive area 25, the polar diameter of the starting point 31 of the arc 24 is smaller than the radial distance from the radial inner end point to the pole of the photosensitive area 25, and the polar diameter of the end point 32 of the arc 24 is larger than the radial distance from the radial outer end point to the pole of the photosensitive area 25.

[0081] The rotation angle θ of the rotating piece 17 is calculated by formula 1 and formula 2:

[0082] (I2-I1) / (I2+I1)=2x / LFormula 1

[0083] θ=(r0+x+b) / a;Formula 2

[0084] In Formula 1, x is the distance between the irradiated position of the photosensitive area 25 and the center position D1 of the photosensitive area 25, L is the length of the photosensitive area 25, I1 is the photocurrent on one side of the position sensitive sensor 18, and I2 is the photocurrent on the other side of the position sensitive sensor 18;

[0085] In formula 2, r0 is the distance from the center D1 of the photosensitive area 25 to the pole of the polar coordinate.

[0086] When the galvanometer assembly 10 of the present embodiment is used, the light emitted by the light source 16 is irradiated to the photosensitive area 25 of the position sensitive sensor 18 through the light-transmitting area 23 of the rotating piece 17, and the irradiated point of the photosensitive area 25 generates two photocurrent signals I2 and I1 under the illumination; the distance x between the irradiated position of the photosensitive area 25 and the center position of the photosensitive area 25 is calculated by the above formula 1, and then the rotation angle θ of the rotating piece 17 can be calculated according to formula 2, that is, the rotation angle θ of the reflector 12 can be obtained;

[0087] The difference between the target angle to which the reflector 12 needs to rotate and the currently measured angle is compared, and the galvanometer motor 11 is controlled to rotate according to the difference until the reflector 12 is driven to rotate to the target angle.

[0088] If the galvanometer motor 11 drives the reflector 12 to rotate until the rotating piece 17 deflects to the left (relative to Figure 2 state) a certain angle, seen in Figure 4At this time, the distance x1 from the intersection 26a between the arc 24 and the photosensitive area 25 to the midpoint D1 of the photosensitive area 25 can be calculated by formula 1, and then the rotation angle θ1 of the rotating piece 17 can be calculated by formula 2.

[0089] Similarly, if the galvanometer motor 11 drives the reflector 12 to rotate until the rotating plate 17 deflects to the right (relative to Figure 2 state) a certain angle, seen in Figure 5 At this time, the distance x2 from the intersection 26b between the arc 24 and the photosensitive area 25 to the midpoint D1 of the photosensitive area can be calculated by formula 1, and then the rotation angle θ2 of the rotating piece 17 can be calculated by formula 2.

[0090] In this embodiment, by providing a rotating piece 17 with a light-transmitting area 23 with a set arc 24 and combining the photoelectric effect of the position sensitive sensor 18, the rotation angle of the rotating piece 17 and the reflector 12 is linearly related to the irradiated position of the photosensitive area 25 (such as Formula 2), the structure and principle are simple, the calculation is convenient, fast and accurate, and the detection result is independent of the luminous intensity and shape of the light source 16, and is only related to the position of the light source 16 on the photosensitive area 25. The current output by the position sensitive sensor 18 can reach the nanoampere level, which can better suppress noise interference and avoid the luminous attenuation of the light source (such as LED, etc.) in some known technologies, which causes the luminous intensity of the photocell to change, thereby affecting the accuracy and stability of the detection result. In addition, the photocell used in some known technologies can only output a maximum current of about 2 microamperes, which is easy to generate noise signals, thereby causing the entire unit to fail completely; the four photocells used in some known technologies are also easily moved due to thermal expansion, which will introduce unnecessary proportional drift into the system and affect the detection accuracy.

[0091] See also Figure 6 This embodiment further provides a metal 3D printing device 100, comprising the aforementioned galvanometer assembly 10. The laser emitted by the laser 80 of the metal 3D printing device 100 can be guided by the rotation of the reflector 12 of the galvanometer assembly 10 to scan the printing surface 200 along a set scanning path.

[0092] This embodiment further provides a galvanometer control method, based on the aforementioned galvanometer assembly 10; the galvanometer control method includes:

[0093] The position detection device 13 obtains the rotation angle information of the rotating piece 17 , and controls the galvanometer motor 11 to rotate to a desired angle according to the rotation angle information.

[0094] The above implementation modes are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred implementation modes, a person skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A position detection device, characterized in that: include: A rotating sheet connected to a galvanometer motor and configured to rotate under the drive of the galvanometer motor; The rotating sheet is provided with a light-transmitting area, and the light-transmitting area is in the shape of a strip extending along an arc; A position sensitive sensor is opposite to the rotating plate along the axial direction of the galvanometer motor; the position sensitive sensor has a photosensitive area, and the photosensitive area is in the shape of a strip extending along the radial direction of the rotating plate; the intersection position of the projection of the light-transmitting area on the plane where the photosensitive area is located and the photosensitive area corresponds to the rotation angle of the rotating plate.

2. The position detection device according to claim 1, characterized in that: The position detection device also includes a light source, which corresponds to the light-transmitting area along the axial direction of the rotating plate. The light emitted by the light source can pass through the light-transmitting area and then illuminate the photosensitive area to form a light spot with a shape corresponding to the shape of the light-transmitting area.

3. The position detection device according to claim 1, characterized in that: The polar coordinate equation of the arc in polar coordinates with the rotation center point of the rotating piece as the pole is r=aθ+b, wherein a and b are constants, a is not equal to 0, θ is the polar angle, r is the polar diameter, and the difference between the polar angles of the starting point and the end point of the arc is less than 2π; The rotation angle θ of the rotating piece is calculated by formula 1 and formula 2: (I2-I1) / (I2+I1)=2x / LFormula 1 θ=(r0+x+b) / a;Formula 2 In Formula 1, x is the distance between the irradiated position of the photosensitive area and the center position of the photosensitive area, L is the length of the photosensitive area, I1 is the photocurrent on one side of the position sensitive sensor, and I2 is the photocurrent on the other side of the position sensitive sensor; In formula 2, r0 is the distance from the center of the photosensitive area to the pole of the polar coordinates.

4. The position detection device according to claim 1, characterized in that: The rotating piece is made of a light-proof material, and the light-transmitting area is an arc-shaped groove opened on the rotating piece, and the arc-shaped groove penetrates the rotating piece along the thickness direction.

5. The position detection device according to claim 1, characterized in that: The rotating plate includes a connecting portion and a rotating plate, the connecting portion is provided with a central hole for being fixedly connected to the rotating shaft of the galvanometer motor, the rotating plate is connected to the connecting portion, and the light-transmitting area is arranged on the rotating plate.

6. The position detection device according to claim 1, characterized in that: The position detection device also includes a mounting plate, the mounting plate is provided with a through hole, and the rotating shaft of the galvanometer motor passes through the through hole and is connected to the rotating plate; the position sensitive sensor is connected to a side of the mounting plate facing the rotating plate.

7. The position detection device according to claim 1, characterized in that: The position sensitive sensor is mounted on a surface of the end cover of the galvanometer motor facing the rotating piece.

8. A galvanometer assembly, characterized in that: include: Reflector; The position detection device according to any one of claims 1 to 7; The galvanometer motor comprises a housing and a rotating shaft, one end of the rotating shaft is connected to the reflector, and the other end is connected to the rotating plate; the position sensitive sensor is located between the galvanometer motor and the rotating plate and is fixed relative to the housing.

9. The galvanometer assembly according to claim 8, characterized in that: It also includes a controller, which is electrically connected to the position detection device and the galvanometer motor and is used to control the movement of the galvanometer motor according to the rotation angle information detected by the position detection device.

10. A metal 3D printing device, characterized in that: include: The galvanometer assembly according to any one of claims 8 to 9.

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