CN110961793A - 3D printing intelligent processing technology based on laser technology - Google Patents

3D printing intelligent processing technology based on laser technology Download PDF

Info

Publication number
CN110961793A
CN110961793A CN201911351730.5A CN201911351730A CN110961793A CN 110961793 A CN110961793 A CN 110961793A CN 201911351730 A CN201911351730 A CN 201911351730A CN 110961793 A CN110961793 A CN 110961793A
Authority
CN
China
Prior art keywords
laser
base material
fixed base
mechanical arm
intelligent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201911351730.5A
Other languages
Chinese (zh)
Inventor
白蕾
朱先勇
朱俊权
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Anhui Radico Intelligent Technology Co Ltd
Original Assignee
Anhui Radico Intelligent Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Anhui Radico Intelligent Technology Co Ltd filed Critical Anhui Radico Intelligent Technology Co Ltd
Priority to CN201911351730.5A priority Critical patent/CN110961793A/en
Publication of CN110961793A publication Critical patent/CN110961793A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36Removing material
    • B23K26/362Laser etching
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/03Observing, e.g. monitoring, the workpiece
    • B23K26/032Observing, e.g. monitoring, the workpiece using optical means
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/70Auxiliary operations or equipment
    • B23K26/702Auxiliary equipment

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Laser Beam Processing (AREA)

Abstract

The invention discloses a 3D printing intelligent processing technology based on a laser technology, which comprises the following steps: s1, setting a printing pattern, and guiding the 3D graph into a laser 3D engraving machine through an image scanning assembly; s2, selecting and installing a fixed base, selecting a matched fixed base according to the size and the shape of the base material, and placing the fixed base in the designated area of the stepping conveying equipment; s3, conveying the base material through a stepping conveying device; s4, performing laser engraving on the base material, and engraving the base material through a laser engraving machine; s5, taking materials, and taking out the fixed base together with the base material through the second intelligent mechanical arm after the base material is well engraved. The 3D printing intelligent processing technology based on the laser technology provided by the invention replaces the existing technology that the base material is conveyed and clamped on the working platform of the laser engraving machine manually, so that the manpower resource is saved, and the poor engraving caused by clamping deviation is avoided.

Description

3D printing intelligent processing technology based on laser technology
Technical Field
The invention belongs to the technical field of laser engraving, and particularly relates to a 3D printing intelligent processing technology based on a laser technology.
Background
The laser engraving processing is based on the numerical control technology, laser is a processing medium, electromechanical transmission is power, and a processing material instantaneously enables the material to be thermally changed and gasified under the action of a laser beam, so that the laser engraving achieves the purpose of processing, and the laser processing is characterized in that: the laser beam focusing device has the advantages of small heat-dissolving area, narrow cutting seam, no surface deformation, high processing precision, high speed and the like in a laser beam focusing range, and has wide application fields.
However, in the prior art, the base materials are conveyed and installed manually, the base materials can cause certain deviation due to different clamping methods and forces when the clamping base materials are placed manually, and poor carving can be caused due to small deviation because the precision of laser carving is high, so that a 3D printing intelligent processing technology based on a laser technology is provided.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides a 3D printing intelligent processing technology based on a laser technology.
In order to achieve the purpose, the invention provides the following technical scheme:
A3D printing intelligent processing technology based on a laser technology comprises the following steps:
s1, setting a printing pattern, and guiding a 3D graph into a laser 3D engraving machine through an image scanning assembly or guiding a paper into the laser 3D engraving machine through drawing software;
s2, selecting and installing a fixed base, selecting a matched fixed base according to the size and the shape of the base material, and placing the fixed base in the designated area of the stepping conveying equipment;
s3, conveying the base material to the upper end of the fixed base through the stepping conveying equipment, wherein the fixed base and the base material are matched in size and shape, the base material can be clamped and fixed on the fixed base through the first intelligent mechanical arm, and then the fixed base and the base material are transferred to a region to be processed through the first intelligent mechanical arm;
s4, carrying out laser engraving on the base material, placing the fixed base placed in the area to be processed and the base material on a working platform of a laser engraving machine through a second intelligent mechanical arm, and engraving the base material through the laser engraving machine;
s5, taking materials, taking out the fixed base together with the base material through a second intelligent mechanical arm after the base material is well engraved, and then putting the engraved base material into a finished product area through the second intelligent mechanical arm;
s6, resetting the fixed base, placing the fixed base in a region to be reset through a second intelligent mechanical arm, and then transferring the fixed base placed in the reset region to a designated region of the stepping conveying equipment through a first intelligent mechanical arm.
Preferably, the substrate described in step S2 includes a transparent glass block, an acryl block, a rubber block, and a crystal block.
Preferably, the step-by-step conveying equipment in the step S2 is a belt step-by-step conveyor, the working environment temperature of the belt step-by-step conveyor is-15-40 ℃, and the temperature of conveyed materials is not more than 50 ℃; the stainless steel mesh belt conveyor is mainly used for plane conveying, plane turning, lifting and descending; roller conveyors are used primarily for conveying substrates having a flat bottom along a horizontal or slightly inclined angle.
Preferably, the first and second smart robot arms in steps S3 and S4 are both configured as smart arms with anti-slip pads fixedly bonded to chucks, each of the first and second smart robot arms includes a controller, an X-axis track, a Z-axis track, a Y-axis track and a gripper, and the gripper is mounted on a sliding table of the Y-axis track; the bottom of the Y-axis track is provided with a movable tray; the gripper comprises a pair of openable clamping jaws, a CCD imaging device and two distance sensors, wherein one of the distance sensors is used for sensing the distance of a to-be-taken goods package in the process that the clamping jaws advance to take the goods package, the other one of the distance sensors is used for sensing the distance of the to-be-taken goods package in the process that the clamping jaws retreat to pull the goods package, the CCD imaging device takes pictures of hanging tabs of the to-be-taken goods package and transmits the obtained images to the controller, and the controller adjusts the positions of the clamping jaws according to the image information.
Preferably, the fixing base mountain in the step S2 is provided with a groove for placing the substrate, and the inside of the fixing base groove is provided with an anti-skid pad block which is set to be a V-shaped anti-skid pad block.
Preferably, the laser engraving machine in step S4 includes a frame, a laser engraving unit disposed on the frame, and a feeding unit facing the laser engraving unit, where the laser engraving unit includes a laser and a scanning camera that move horizontally along the frame; the feeding unit comprises a feeding belt which is over against the laser and the scanning camera, and the feeding belt is driven by a first transmission mechanism arranged on the rack; the frame upper shield is equipped with the safety cover, the safety cover both sides are equipped with the window that supplies the product business turn over, be equipped with in the frame along its lift, can shelter from the shielding plate of window, just the shielding plate bottom is equipped with damping buffer gear.
Preferably, the laser engraving unit comprises two groups of laser heads which are vertically arranged on the same plane, and lasers emitted by the two groups of laser heads are intersected in the substrate to sinter and print the inside of the substrate.
The invention has the technical effects and advantages that: according to the 3D printing intelligent processing technology based on the laser technology, provided by the invention, the base material is conveyed through the stepping type conveying equipment, the base material is clamped and fixed on the fixed base through the first intelligent mechanical arm and the fixed base and the base material are transferred to the area to be processed together, then the fixed base and the base material which are placed in the area to be processed are placed on the working platform of the laser engraving machine through the second intelligent mechanical arm, the base material is engraved through the laser engraving machine, then the engraved finished product is separated from the fixed base through the second intelligent mechanical arm, and the fixed base is reset through the first intelligent mechanical arm, so that the existing process that the base material is conveyed and clamped on the working platform of the laser engraving machine manually is replaced, the human resources are saved, and meanwhile, poor engraving caused by clamping deviation is avoided to a certain extent.
Drawings
Fig. 1 is a flow chart of the laser technology-based 3D printing intelligent processing process of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A3D printing intelligent processing technology based on a laser technology comprises the following steps:
s1, setting a printing pattern, and guiding a 3D graph into a laser 3D engraving machine through an image scanning assembly or guiding a paper into the laser 3D engraving machine through drawing software;
s2, selecting and installing a fixed base, selecting a matched fixed base according to the size and the shape of the base material, and placing the fixed base in the designated area of the stepping conveying equipment; the substrate comprises a transparent glass block, an acrylic block, a rubber block and a crystal block; the step-by-step conveying equipment is a belt-type step-by-step conveyor, the working environment temperature of the belt-type step-by-step conveyor is-15-40 ℃, and the temperature of conveyed materials is not more than 50 ℃; the stainless steel mesh belt conveyor is mainly used for plane conveying, plane turning, lifting and descending; roller conveyors are used primarily for conveying substrates having a flat bottom along a horizontal or slightly inclined angle.
S3, conveying the base material to the upper end of the fixed base through the stepping conveying equipment, wherein the fixed base and the base material are matched in size and shape, the base material can be clamped and fixed on the fixed base through the first intelligent mechanical arm, and then the fixed base and the base material are transferred to a region to be processed through the first intelligent mechanical arm;
s4, carrying out laser engraving on the base material, placing the fixed base placed in the area to be processed and the base material on a working platform of a laser engraving machine through a second intelligent mechanical arm, and engraving the base material through the laser engraving machine; the first intelligent mechanical arm and the second intelligent mechanical arm in the steps S3 and S4 are both set as intelligent arms with clamping heads fixedly adhered with anti-slip pads, the first intelligent mechanical arm and the second intelligent mechanical arm respectively comprise a controller, an X-axis track, a Z-axis track, a Y-axis track and a mechanical claw, and the mechanical claw is installed on a sliding table of the Y-axis track; the bottom of the Y-axis track is provided with a movable tray; the gripper includes a pair of clamping jaw that can open and shut, a CCD imaging device and two distance sensor, one of them distance sensor is used for the response the clamping jaw is preceding to get the distance of the package of waiting to get in-process, another distance sensor is used for the response the clamping jaw is backed and is pulled the distance of the package of waiting to get in-process, CCD imaging device is treated the hanging tong "pan" of getting the package and is taken a picture to image transmission to the controller that will obtain, the controller adjusts the position of clamping jaw according to image information, the laser sculpture unit includes two sets of laser heads that are located the perpendicular setting of coplanar, the laser that two sets of laser heads were launched intersects inside the substrate, carries out the sintering to the inside of substrate and prints.
S5, taking materials, taking out the fixed base together with the base material through a second intelligent mechanical arm after the base material is well engraved, and then putting the engraved base material into a finished product area through the second intelligent mechanical arm;
s6, resetting the fixed base, placing the fixed base in a region to be reset through a second intelligent mechanical arm, and then transferring the fixed base placed in the reset region to a designated region of the stepping conveying equipment through a first intelligent mechanical arm.
In summary, the following steps: compared with the traditional laser engraving, the 3D printing intelligent processing technology based on the laser technology provided by the invention has the advantages that the base material is conveyed through the stepping type conveying equipment, the base material is clamped and fixed on the fixed base through the first intelligent mechanical arm, the fixed base and the base material are transferred to a region to be processed, then the fixed base arranged in the area to be processed and the base material are arranged on a working platform of the laser engraving machine through a second intelligent mechanical arm, the base material is carved by a laser carving machine, and then a carved finished product is separated from the fixed base by a second intelligent mechanical arm, the unable adjustment base resets through first intelligent arm, replaces current through artifical carry the substrate and clamp on laser engraving machine's work platform, when having practiced thrift manpower resources, also avoided to a certain extent because the sculpture that the clamping deviation leads to is bad.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.

Claims (7)

1. The 3D printing intelligent processing technology based on the laser technology is characterized by comprising the following steps of:
s1, setting a printing pattern, and guiding a 3D graph into a laser 3D engraving machine through an image scanning assembly or guiding a paper into the laser 3D engraving machine through drawing software;
s2, selecting and installing a fixed base, selecting a matched fixed base according to the size and the shape of the base material, and placing the fixed base in the designated area of the stepping conveying equipment;
s3, conveying the base material to the upper end of the fixed base through the stepping conveying equipment, wherein the fixed base and the base material are matched in size and shape, the base material can be clamped and fixed on the fixed base through the first intelligent mechanical arm, and then the fixed base and the base material are transferred to a region to be processed through the first intelligent mechanical arm;
s4, carrying out laser engraving on the base material, placing the fixed base placed in the area to be processed and the base material on a working platform of a laser engraving machine through a second intelligent mechanical arm, and engraving the base material through the laser engraving machine;
s5, taking materials, taking out the fixed base together with the base material through a second intelligent mechanical arm after the base material is well engraved, and then putting the engraved base material into a finished product area through the second intelligent mechanical arm;
s6, resetting the fixed base, placing the fixed base in a region to be reset through a second intelligent mechanical arm, and then transferring the fixed base placed in the reset region to a designated region of the stepping conveying equipment through a first intelligent mechanical arm.
2. The production process of the 3D printing intelligent processing technology based on the laser technology, according to claim 1, is characterized in that: the base material in the step S2 includes a transparent glass block, an acrylic block, a rubber block, and a crystal block.
3. The production process of the 3D printing intelligent processing technology based on the laser technology, according to claim 1, is characterized in that: the step-by-step conveying equipment in the step S2 is a belt-type step conveyor, the working environment temperature of the belt-type step conveyor is-15-40 ℃, and the temperature of conveyed materials is not more than 50 ℃; the stainless steel mesh belt conveyor is mainly used for plane conveying, plane turning, lifting and descending; roller conveyors are used primarily for conveying substrates having a flat bottom along a horizontal or slightly inclined angle.
4. The production process of the 3D printing intelligent processing technology based on the laser technology, according to claim 1, is characterized in that: the first intelligent mechanical arm and the second intelligent mechanical arm in the steps S3 and S4 are both set as intelligent arms with clamping heads fixedly adhered with anti-slip pads, the first intelligent mechanical arm and the second intelligent mechanical arm respectively comprise a controller, an X-axis track, a Z-axis track, a Y-axis track and a mechanical claw, and the mechanical claw is installed on a sliding table of the Y-axis track; the bottom of the Y-axis track is provided with a movable tray; the gripper comprises a pair of openable clamping jaws, a CCD imaging device and two distance sensors, wherein one of the distance sensors is used for sensing the distance of a to-be-taken goods package in the process that the clamping jaws advance to take the goods package, the other one of the distance sensors is used for sensing the distance of the to-be-taken goods package in the process that the clamping jaws retreat to pull the goods package, the CCD imaging device takes pictures of hanging tabs of the to-be-taken goods package and transmits the obtained images to the controller, and the controller adjusts the positions of the clamping jaws according to the image information.
5. The production process of the 3D printing intelligent processing technology based on the laser technology, according to claim 1, is characterized in that: the fixed base mountain in the step S2 is provided with a groove for placing a base material, an anti-skid cushion block is arranged inside the fixed base groove, and the anti-skid cushion block is a V-shaped anti-skid cushion block.
6. The production process of the 3D printing intelligent processing technology based on the laser technology, according to claim 1, is characterized in that: the laser engraving machine comprises a frame, a laser engraving unit arranged on the frame and a feeding unit right opposite to the laser engraving unit, wherein the laser engraving unit comprises a laser and a scanning camera which horizontally move along the frame; the feeding unit comprises a feeding belt which is over against the laser and the scanning camera, and the feeding belt is driven by a first transmission mechanism arranged on the rack; the frame upper shield is equipped with the safety cover, the safety cover both sides are equipped with the window that supplies the product business turn over, be equipped with in the frame along its lift, can shelter from the shielding plate of window, just the shielding plate bottom is equipped with damping buffer gear.
7. The production process of the 3D printing intelligent processing technology based on the laser technology, according to claim 6, is characterized in that: the laser engraving unit comprises two groups of laser heads which are vertically arranged on the same plane, and lasers emitted by the two groups of laser heads are intersected inside the substrate to sinter and print the inside of the substrate.
CN201911351730.5A 2019-12-24 2019-12-24 3D printing intelligent processing technology based on laser technology Pending CN110961793A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201911351730.5A CN110961793A (en) 2019-12-24 2019-12-24 3D printing intelligent processing technology based on laser technology

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201911351730.5A CN110961793A (en) 2019-12-24 2019-12-24 3D printing intelligent processing technology based on laser technology

Publications (1)

Publication Number Publication Date
CN110961793A true CN110961793A (en) 2020-04-07

Family

ID=70036510

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201911351730.5A Pending CN110961793A (en) 2019-12-24 2019-12-24 3D printing intelligent processing technology based on laser technology

Country Status (1)

Country Link
CN (1) CN110961793A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113059800A (en) * 2021-02-19 2021-07-02 浙江工贸职业技术学院 Laser engraving and thermal fusion molding 3D printing method and 3D printing equipment
CN113695768A (en) * 2020-05-21 2021-11-26 大族激光科技产业集团股份有限公司 Method for machining pressure relief hole of earphone by laser
CN115003446A (en) * 2020-12-23 2022-09-02 深圳市创客工场科技有限公司 Machining method, machining device, computer-readable storage medium, and electronic apparatus

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN202647227U (en) * 2012-01-09 2013-01-02 吴强 Multifunctional LED light source laser inner carving lamp
CN202753671U (en) * 2012-08-28 2013-02-27 济南金威刻科技发展有限公司 Drum location mechanism of drum type laser engraving machine
CN105855718A (en) * 2016-03-30 2016-08-17 苏州恩欧西智能科技有限公司 Laser engraving machine
CN105856853A (en) * 2016-03-30 2016-08-17 苏州恩欧西智能科技有限公司 Laser engraving machine
CN108655593A (en) * 2018-05-04 2018-10-16 深圳市博瑞特激光科技有限责任公司 A kind of glass substrate laser perforation processing device and processing method
CN108927793A (en) * 2017-05-24 2018-12-04 科思通自动化设备(苏州)有限公司 Automatic intelligent stores mechanical arm
CN110548998A (en) * 2019-08-23 2019-12-10 苏州米氪激光技术服务有限公司 Small-size stone carving laser engraving device

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN202647227U (en) * 2012-01-09 2013-01-02 吴强 Multifunctional LED light source laser inner carving lamp
CN202753671U (en) * 2012-08-28 2013-02-27 济南金威刻科技发展有限公司 Drum location mechanism of drum type laser engraving machine
CN105855718A (en) * 2016-03-30 2016-08-17 苏州恩欧西智能科技有限公司 Laser engraving machine
CN105856853A (en) * 2016-03-30 2016-08-17 苏州恩欧西智能科技有限公司 Laser engraving machine
CN108927793A (en) * 2017-05-24 2018-12-04 科思通自动化设备(苏州)有限公司 Automatic intelligent stores mechanical arm
CN108655593A (en) * 2018-05-04 2018-10-16 深圳市博瑞特激光科技有限责任公司 A kind of glass substrate laser perforation processing device and processing method
CN110548998A (en) * 2019-08-23 2019-12-10 苏州米氪激光技术服务有限公司 Small-size stone carving laser engraving device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113695768A (en) * 2020-05-21 2021-11-26 大族激光科技产业集团股份有限公司 Method for machining pressure relief hole of earphone by laser
CN115003446A (en) * 2020-12-23 2022-09-02 深圳市创客工场科技有限公司 Machining method, machining device, computer-readable storage medium, and electronic apparatus
CN113059800A (en) * 2021-02-19 2021-07-02 浙江工贸职业技术学院 Laser engraving and thermal fusion molding 3D printing method and 3D printing equipment

Similar Documents

Publication Publication Date Title
CN110961793A (en) 3D printing intelligent processing technology based on laser technology
CN204602651U (en) A kind of AOI checkout equipment
JP2013215825A (en) Workpiece conveyance system
JP3739333B2 (en) Sheet glass cleaving system
CN108580783A (en) A kind of automatic riveting system based on machine vision
KR101530245B1 (en) Board printing apparatus
JP2001158413A (en) Labeling device
KR20100084985A (en) Laser patterning method and laser patterning equipment
CN110735236A (en) robot sewing device
TWI804856B (en) Resin molding device
CN211135919U (en) Ceramic material laser scribing processing device
CN112224868A (en) FPC (Flexible printed Circuit) light bar feeding method based on CCD (Charge coupled device)
CN111699056B (en) Automatic feeding and discharging device and method of vision-based punching machine and punching equipment
CN208555095U (en) A kind of refractive body surface detection apparatus based on machine vision
CN211442911U (en) Full-automatic auxiliary material pasting machine
CN213364610U (en) Automatic optical detection device for detecting hot bending product
CN109585611B (en) Battery string typesetting method and battery string typesetting machine applying same
CN109178521B (en) Labeling device capable of preventing edge from being warped efficiently
CN213798650U (en) Screen printing machine
JP2011143548A (en) Screen printing machine and screen printing method
CN114799533A (en) Horizontal multi-station film removing equipment
CN219543282U (en) Automatic cutting equipment of VR lens
CN112338988A (en) Robot-based control method for sheet lamination forming production line
CN214109222U (en) Business card holder laser engraving device
CN219577411U (en) Automatic copper foil attaching equipment

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
RJ01 Rejection of invention patent application after publication
RJ01 Rejection of invention patent application after publication

Application publication date: 20200407