CN115213436A

CN115213436A - Double-material accurate powder laying device for SLM and control method thereof

Info

Publication number: CN115213436A
Application number: CN202210868981.6A
Authority: CN
Inventors: 朱利斌; 聂帅帅; 黄海鸿; 杨熙龙; 彭开元
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2022-07-22
Filing date: 2022-07-22
Publication date: 2022-10-21
Anticipated expiration: 2042-07-22
Also published as: CN115213436B

Abstract

The invention discloses a double-material accurate powder spreading device for an SLM (Selective laser melting) and a control method thereof, which relate to the technical field of additive manufacturing and comprise a plurality of powder feeding and dropping mechanisms and powder spreading mechanisms which are arranged on an installation flat plate, wherein a forming opening is formed in the installation flat plate, and a forming cylinder is correspondingly arranged at the forming opening; and the conveying mechanism of the powder paving mechanism is used for driving the scraper mechanism of the powder paving mechanism to do linear motion to and fro between the powder feeding and discharging mechanism and the forming cylinder so as to realize powder paving and feeding in additive manufacturing. The scraper mechanism receives and temporarily stores the metal powder supplied by the powder feeding and dropping mechanism at a loading position, and then conveys the metal powder to a printing position corresponding to a forming cylinder to be uniformly spread; multiple metal powders can be supplied through multiple powder feeding and dropping mechanisms, and additive manufacturing of multiple materials is realized without stopping the machine; go up powder falling mechanism and realize metal powder's ration supply through the hold-in range that is equipped with the trough of belt, reduced metal powder's waste, reduced the degree of difficulty of cleaning work behind the vibration material disk manufacturing operation.

Description

Double-material accurate powder laying device for SLM and control method thereof

Technical Field

The invention relates to the technical field of additive manufacturing, in particular to a powder laying mechanism for selective laser melting additive manufacturing powder supply.

Background

Additive Manufacturing (AM) is a rapid prototyping technique that accumulates materials layer by layer based on three-dimensional model data to form a solid body, using an "Additive" manufacturing approach as opposed to the traditional "subtractive" manufacturing approach. Additive manufacturing is an advanced manufacturing technology that combines material science, mechanical automation, and information technology. With the development of the technology level, the additive manufacturing is more widely applied and plays an increasingly important role.

Metal material additive manufacturing is one of the most important components of additive manufacturing technology, and is the main research direction of advanced manufacturing technology. The additive manufacturing technology includes seven categories, i.e., binder Jetting (Binder Melting), powder Bed Melting (Powder Bed Melting), direct Energy Deposition (direct Energy Deposition), lamination (Sheet Lamination), material Jetting (Material Melting), photopolymerization (Vat Photopolymerization), and Material Extrusion (Material Extrusion), and a Selective Laser Melting (SLM) technology suitable for additive manufacturing of a metal Material is one of the Powder Bed Melting technologies.

The material increasing principle of the selective laser melting technology is that enough metal powder is put into a powder feeding cylinder in advance, a forming cylinder descends to a certain height during printing, the powder cylinder ascends to a certain height, a certain amount of powder uniformly falls out of the powder feeding cylinder to the forming cylinder under the action of a scraper, then the moving track and the power intensity of laser are adjusted by controlling a vibrating mirror, the metal powder in a selected area is melted, single-layer forming is completed, and the required metal component can be obtained by repeating multiple times of single-layer forming.

The existing selective laser melting technology can only realize additive manufacturing of single materials, cannot meet the requirement of dual-material additive manufacturing, and a large amount of metal powder needs to be put in advance before processing to ensure normal operation of the manufacturing process, so that a large amount of waste of raw materials is caused, and the workload of cleaning after processing is heavy.

By prior art search, the following known solutions exist:

prior art 1:

application No.: CN202020712718.4, application date: 2020.04.30, published (public) day: 2021.04.30, the utility model provides a powder spreading device for multi-metal materials, comprising a working platform, a bracket, a first powder supply cylinder, a second powder supply cylinder, a first powder spreading scraper, a second powder spreading scraper and a driving mechanism; the first powder supply cylinder comprises a storage bin, a first material opening and a first cover plate, the second powder supply cylinder comprises a storage bin, a second material opening and a second cover plate, the first material opening and the second material opening are identical, the first material opening and the second material opening are in a long-strip rectangle, the second cover plate is arranged on the second material opening through two guide rails parallel to the short edge of the second material opening, the second cover plate slides along the guide rails, the outer edge of the first cover plate is overlapped or interfered with the edge of the first material opening, and the second cover plate is overlapped or interfered with the edge of the second material opening; the driving mechanism drives the support to do reciprocating motion relative to the working platform. The powder spreading device of the utility model realizes the simultaneous spreading of different kinds of powder; and the proportion adjustment of different types of metal powder is realized during powder paving.

The powder falling process in the prior art can not be quantified, the amount of the falling powder can not be estimated, the adjustment can only be performed through shaking the adjusting mechanism for many times, the loss of raw materials is large, and the burden of the cleaning work after processing is heavy.

Prior art 2:

application No.: CN201020671362.0, application date: 2010, 12.21, publication (announcement) day: 2011.11.09, the utility model provides an adopt selectivity laser sintering single face powder feeding device who returns powder groove and realize, including spreading the powder roller, sending the powder jar, overflowing the powder jar and returning the powder groove, this single face powder feeding device only need send powder jar and one overflow the powder jar in one side-mounting of workstation, return the powder groove in opposite side installation of workstation, wherein return the control shaft that the powder groove includes a cylinder body, a movable bottom plate and is connected with movable bottom plate. The utility model discloses practice thrift the equipment space, reduced the equipment size, reduced equipment complexity, effectively reduced equipment cost, promoted equipment reliability, further satisfied SLS technological requirement.

The prior art is only suitable for additive manufacturing of a single material, and is difficult to meet the requirement of additive manufacturing of two or more materials.

The search finds that the technical scheme does not influence the novelty of the invention; and the mutual combination of the above prior arts does not destroy the inventive idea of the present invention.

Disclosure of Invention

The invention provides a bi-material precise powder laying device for an SLM (selective laser melting) and a control method thereof, aiming at overcoming the defects of the prior art.

The invention adopts the following technical scheme for solving the technical problems: a double-material accurate powder spreading device for an SLM comprises an upper powder dropping mechanism and a powder spreading mechanism which are arranged on an installation flat plate, wherein a forming opening is formed in the installation flat plate, and a forming cylinder is correspondingly arranged at the forming opening;

powder feeding and discharging mechanism

The powder storage bin is fixedly arranged above the mounting flat plate through a support, and a discharge hole is formed in the bottom of the powder storage bin; the pair of supports are oppositely arranged and are fixedly arranged on the installation flat plate, the driving shaft and the driven shaft are rotatably arranged on the pair of supports, and the axes of the driving shaft and the driven shaft are arranged in parallel; the powder falling stepping motor is arranged on the support or the installation flat plate, and an output shaft of the powder falling stepping motor is fixedly connected with one end of the driving shaft; synchronous belt wheels are fixedly arranged on the driving shaft and the driven shaft, and the synchronous belts are tensioned on the synchronous belt wheels on the driving shaft and the driven shaft; the synchronous belt is positioned in the powder storage bin, one end of the synchronous belt is arranged at a position corresponding to the discharge hole, and strip-shaped belt grooves are uniformly distributed on the outer surface of the synchronous belt;

powder paving mechanism

The scraper mechanism comprises an upper plate, a lower plate, a powder storage block, a fixed supporting plate, a scraper blade and a linear actuating mechanism, wherein the upper plate is provided with a strip-shaped blanking hole matched with the discharge port, the top surface of the lower plate is provided with a chute, the bottom of the chute is provided with a discharge hole, the powder storage block is arranged in the chute in a sliding fit manner, and a strip-shaped powder storage hole is formed in the powder storage block;

the upper plate is fixedly arranged at the top of the lower plate, the upper plate and the lower plate are arranged on the execution end of the conveying mechanism through the fixed supporting plate, and the conveying mechanism is used for driving the scraper mechanism to do linear motion between the upper powder falling mechanism and the forming cylinder;

the linear actuating mechanism is fixedly arranged on the upper plate, the lower plate or the fixed supporting plate, and the output end of the linear actuating mechanism is embedded into the chute and is fixedly connected with the powder storage block; the linear actuating mechanism is used for driving the powder storage block to slide in the sliding chute to a first station where only the top of the powder storage hole is communicated with the blanking hole or a second station where only the bottom of the powder storage hole is communicated with the discharging hole; the scraper blade is fixedly arranged at the bottom of the lower plate.

Furthermore, the powder spreading device comprises at least two powder feeding and dropping mechanisms which are arranged in the same direction along the linear motion direction.

Furthermore, the number of the blanking holes and the number of the powder storage holes correspond to the number of the powder feeding mechanisms, the number of the discharge holes corresponds to the number of the powder storage holes or is one less than the number of the powder storage holes, the blanking holes and the powder storage holes are correspondingly arranged in parallel at intervals consistent with the intervals of the synchronous belts of the powder feeding mechanisms, and the discharge holes and the powder storage holes are arranged in an offset manner.

Furthermore, the transportation mechanism comprises a pair of guide slide rails which are arranged in parallel, guide slide blocks are connected to the guide slide rails in a sliding fit manner, and the guide slide blocks are used as execution ends of the transportation mechanism and are correspondingly installed and fixed with the fixed supporting plate;

the two pairs of transportation supports are respectively and oppositely arranged at two ends of the two guide sliding rails, the two transportation transmission shafts are arranged in parallel and are respectively and rotatably installed on the two pairs of transportation supports, any one of the two transmission shafts is used as a driving transmission shaft, the other transmission shaft is used as a driven transmission shaft, and one end of the driving transmission shaft is fixedly connected with the output end of a transportation motor which is fixedly installed;

the conveying belt clamping device is characterized in that conveying belt wheels serving as a driving belt wheel and a driven belt wheel are respectively fixedly mounted on the driving transmission shaft and the driven transmission shaft, conveying belts are tensioned on the driven belt wheels and the driving belt wheels, conveying belt pressing sheets are arranged on the conveying belts, and the conveying belt pressing sheets are fixedly connected with corresponding fixed supporting plates.

Further, the synchronous belt pulley is a single-flange synchronous belt pulley, and the synchronous belt pulley is connected with a driving shaft or a driven shaft provided with an A-shaped flat key in a matching manner through a key slot formed in the synchronous belt pulley;

the conveying belt wheels are double-flange belt wheels which are arranged in pairs, the two pairs of double-flange belt wheels are respectively installed and fixed at two ends of the driving transmission shaft and the driven transmission shaft, the number of the conveying belts is correspondingly two, and each conveying belt is respectively tensioned on the corresponding group of driving belt wheels and the corresponding driven belt wheels.

Further, the width of the groove is 15-400 times of the diameter of the powder particles, and the depth of the groove is 3-100 times of the diameter of the powder particles.

Furthermore, the driving shaft is rotatably installed on a pair of supports through a deep groove ball bearing, an output shaft of the powder falling stepping motor is fixedly connected with the driving shaft and an output end of the driving transmission shaft and an output end of the transportation motor through quincunx elastic couplings, and the powder storage bin is fixedly connected with the support through an inner hexagonal socket head cap screw.

Furthermore, a recovery hole is formed in the mounting flat plate, the residual powder collecting tank is correspondingly arranged below the recovery hole and is mounted on the mounting flat plate, and a screen plate is covered at the recovery hole; and a collecting plate detachably matched with the powder storage bin and inserted is arranged below the synchronous belt.

A control method of a bi-material precise powder laying device for an SLM comprises the following steps:

step one, setting the number of the powder feeding mechanisms according to actual needs, and filling sufficient metal powder of different types into the powder storage bin of each powder feeding mechanism;

secondly, guiding the printed model into a computer, calculating the powder quantity required by one-layer additive manufacturing according to the powder quantitative conveying model, confirming that the powder quantity corresponds to the required belt groove quantity, and then writing an MCU control program to input into a singlechip;

thirdly, the forming cylinder is lifted until the distance between the forming cylinder and the scraper blade meets the set initial value distance;

fourthly, the transport motor drives the fixed supporting plate to slide along the guide sliding rail under the guide effect of the guide sliding block through the transport belt wheel and the transport belt, so as to drive the scraper mechanism to move to the loading position, and meanwhile, the linear actuating mechanism drives the powder storage block to slide in the sliding groove to the first station, so that the powder storage hole is communicated with the blanking hole and is positioned right below the discharging position of the appointed upper blanking mechanism;

fifthly, controlling a powder falling motor to drive a synchronous belt to rotate by a set angle at a set rotating speed by a single chip microcomputer, sending out a set amount of powder from a powder storage bin through a set number of belt grooves, and dropping the powder into a powder storage hole for temporary storage through a material dropping hole at a discharging position;

sixthly, the transport motor drives the scraper mechanism to move to a printing position at a set transport speed, so that the scraper mechanism reaches the position above the edge of the forming cylinder;

seventhly, the transport motor drives the scraper mechanism to move forwards continuously, so that the scraper mechanism moves over the forming cylinder at a set printing speed; in the process, the linear actuating mechanism drives the powder storage block to slide in the chute to the second station, so that the powder storage hole is communicated with the discharge hole, and the powder temporarily stored in the powder storage hole falls onto the forming cylinder through the discharge hole and is uniformly paved under the action of the scraper blade;

step eight, sintering the designated area on the layer of powder by a laser system to complete the additive manufacturing of the layer;

step nine, the forming cylinder descends by the height of one step pitch, and then the next layer of additive manufacturing is carried out according to the method from step four to step eight until additive manufacturing is completed.

Further, the powder quantitative conveying model is established according to the following method:

in the fifth step, the singlechip controls the powder dropping motor to drive the synchronous belt to rotate through a set angle at a set rotating speed, the set angle is used for enabling powder in n belt grooves to drop from the discharging position of the powder dropping mechanism, and n is determined according to the following formula:

wherein a is the side length of the square forming cylinder, d is the thickness of powder required by single-layer additive manufacturing, and S is a safe supply coefficient. The invention provides a double-material accurate powder laying device for an SLM (Selective laser melting) and a control method thereof, which have the following beneficial effects:

1. the scraper mechanism is driven by the conveying mechanism to reciprocate between the powder feeding and discharging mechanism and the forming cylinder, receives and temporarily stores the metal powder supplied by the powder feeding and discharging mechanism at a loading position corresponding to the powder feeding and discharging mechanism, and then conveys the metal powder to a printing position corresponding to the forming cylinder to be uniformly spread; the powder feeding and discharging mechanism realizes the quantitative supply of metal powder through a synchronous belt with a groove, so that the waste of the metal powder is reduced, and the difficulty of cleaning after the additive manufacturing operation is reduced;

2. according to the multi-material additive manufacturing device, the plurality of powder feeding and discharging mechanisms can be arranged to realize the supply of different metal materials, and through the cooperative work of the powder spreading mechanism and the plurality of powder feeding and discharging mechanisms, single-layer additive manufacturing is taken as a unit under the condition of no shutdown, so that the multi-material additive manufacturing is realized, the complexity of multi-material additive manufacturing operation is greatly simplified, and the efficiency of multi-material additive manufacturing is improved;

3. according to the scraper mechanism, the powder storage block can prevent metal powder from falling out in the first station state, metal powder discharging is realized in the second station state, the conveying mechanism can drive the scraper mechanism to rapidly move through a non-forming area in the first station state of the powder storage block and drive the scraper mechanism to move at a feeding speed in the second station state of the powder storage block, the feeding stroke of the scraper in the non-forming area is reduced, and the additive manufacturing efficiency is further improved;

4. the invention adopts a symmetrical structural form, and improves the space utilization rate.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic structural view of a powder feeding and discharging mechanism according to the present invention;

FIG. 3 is a schematic structural view of the powder spreading mechanism of the present invention;

FIG. 4 is a schematic structural view of a powder storage bin according to the present invention;

FIG. 5 is a schematic diagram of the structure of the synchronous belt of the present invention;

FIG. 6 is a schematic view of the assembly structure of the synchronous belt with the driving shaft and the driven shaft of the present invention;

FIG. 7 is a schematic view of the construction of the doctor mechanism of the invention;

FIG. 8 is a schematic view of the forming cylinder of the present invention;

fig. 9 is a schematic structural view of a lower plate according to the present invention.

In the figure:

1. installing a flat plate 11, a forming opening 12, a recovery hole 13 and a screen plate; 2. the powder feeding and dropping mechanism 21, the support 22, the powder storage bin 221, the discharge hole 23, the support 24, the driving shaft 25, the driven shaft 26, the powder dropping motor 27, the synchronous belt wheel 28, the synchronous belt 281, the belt groove 29 and the collecting plate; 4. the powder spreading mechanism 41, the conveying mechanism 411, the guide sliding rail 412, the guide sliding block 413, the conveying support 414, the conveying transmission shaft 415, the conveying motor 416, the conveying belt wheel 417, the conveying belt 418 and the conveying belt pressing sheet; 42. the scraper mechanism 421, an upper plate, 4211, a blanking hole, 422, a lower plate, 4221, a sliding groove, 4222, a discharging hole, 423, a powder storage block, 4231, a powder storage hole, 424, a fixed supporting plate, 425, a scraper edge, 426 and a linear actuating mechanism; 5. a residual powder collecting tank; 6. and (5) forming the cylinder.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.

As shown in fig. 1 to 9, the structural relationship is as follows: the powder feeding and discharging device comprises an upper powder discharging mechanism 2 and a powder spreading mechanism 4 which are arranged on an installation flat plate 1, wherein a forming opening 11 is formed in the installation flat plate 1, and a forming cylinder 6 is correspondingly arranged at the forming opening 11;

powder feeding and discharging mechanism 2

The powder storage bin 22 is fixedly arranged above the mounting flat plate 1 through a bracket 21, and the bottom of the powder storage bin is provided with a discharge port 221; the pair of supports 23 are oppositely arranged and are fixedly arranged on the mounting flat plate 1, and the driving shaft 24 and the driven shaft 25 are rotatably arranged on the pair of supports 23, and the axes of the driving shaft and the driven shaft are arranged in parallel; the powder falling stepping motor 26 is arranged on the support 23 or the installation flat plate 1, and an output shaft of the powder falling stepping motor is fixedly connected with one end of the driving shaft 24; a synchronous belt pulley 27 is fixedly arranged on the driving shaft 24 and the driven shaft 25, and a synchronous belt 28 is tensioned on the synchronous belt pulley 27 on the driving shaft 24 and the driven shaft 25; the synchronous belt 28 is positioned in the powder storage bin 22, one end of the synchronous belt 28 is arranged corresponding to the position of the discharge hole 221, and strip-shaped belt grooves 281 are uniformly distributed on the outer surface of the synchronous belt 28;

powder paving mechanism 4

The scraper mechanism 42 comprises an upper plate 421, a lower plate 422, a powder storage block 423, a fixed supporting plate 424, a scraper blade 425 and a linear actuator 426, wherein the upper plate 421 is provided with a strip-shaped blanking hole 4211 matched with the discharge hole 221, the top surface of the lower plate 422 is provided with a sliding groove 4221, the bottom of the sliding groove is provided with a discharge hole 4222, the powder storage block 423 is arranged in the sliding groove 4221 in a sliding fit manner, and the powder storage block 423 is provided with a strip-shaped powder storage hole 4231;

the upper plate 421 is fixedly mounted on the top of the lower plate 422, the upper plate 421 and the lower plate 422 are mounted on the executing end of the conveying mechanism 41 through the fixed supporting plate 424, and the conveying mechanism 41 is used for driving the scraper mechanism 42 to do linear motion to and fro between the powder feeding and discharging mechanism 2 and the forming cylinder 6;

the linear actuating mechanism 426 is fixedly arranged on the upper plate 421, the lower plate 422 or the fixed supporting plate 424, and the output end of the linear actuating mechanism is embedded into the chute 4221 and is fixedly connected with the powder storage block 423; the linear actuator 426 is used for driving the powder storage block 423 to slide in the chute 4221 to a first station where only the top of the powder storage hole 4231 is communicated with the blanking hole 4211 or a second station where only the bottom of the powder storage hole 4231 is communicated with the discharging hole 4222; a doctor blade 425 is fixedly mounted to the bottom of the lower plate 422.

Preferably, the powder laying device comprises at least two powder feeding mechanisms 2 which are arranged in the same direction along the linear motion direction.

Preferably, the number of the blanking holes 4211 and the powder storing holes 4231 is corresponding to the number of the upper powder dropping mechanisms 2, the number of the discharging holes 4222 is corresponding to the number of the powder storing holes 4231 or is one less than the number of the powder storing holes 4231, each blanking hole 4211 and each powder storing hole 4231 are correspondingly arranged in parallel at a distance consistent with the distance of the synchronous belt 28 of each upper powder dropping mechanism 2, and each discharging hole 4222 and each powder storing hole 4231 are arranged in an offset manner; each powder storage hole 4231 can slide to a first station communicated with only one blanking hole 4211 corresponding to the top of the powder storage hole under the driving of the linear actuator 426, or a second station communicated with only one discharging hole 4222 corresponding to the bottom of the powder storage hole; under this setting, when scraper mechanism 42 is located the loading position, every group deposit whitewashed hole 4231 and blanking hole 4211 correspond to be located on one respectively and fall under the 2 ejection of compact positions of whitewashed mechanism, can make scraper mechanism 42 when carrying out the loading of different kinds of metal powder, be located same loading position all the time, do benefit to the simplification of programming.

Preferably, the transportation mechanism 41 includes a pair of guide rails 411 arranged in parallel, a guide slider 412 is connected on the guide rails 411 in a sliding fit manner, and the guide slider 412 and the guide rails 411 form a sliding pair along the guide rails 411; the guide sliding block 412 is used as an execution end of the transportation mechanism 41 and is correspondingly installed and fixed with the fixed supporting plate 424;

two pairs of transportation supports 413 are respectively and oppositely arranged at two ends of the two guide sliding rails 411, two transportation transmission shafts 414 are arranged in parallel and are respectively and rotatably installed on the two pairs of transportation supports 413, any one of the two transmission shafts 414 is used as a driving transmission shaft, the other one is used as a driven transmission shaft, and one end of the driving transmission shaft is fixedly connected with the output end of a transportation motor 415 which is fixedly installed;

the driving transmission shaft and the driven transmission shaft are respectively provided with and fixed with a conveying belt wheel 416 serving as a driving belt wheel and a driven belt wheel, a conveying belt 417 is tensioned on the driven belt wheel and the driving belt wheel, a conveying belt pressing sheet 418 is arranged on the conveying belt 417, and the conveying belt pressing sheet 418 is fixedly connected with a corresponding fixed supporting plate 424.

Preferably, the synchronous belt pulley 27 is a single-flange synchronous belt pulley, and the synchronous belt pulley 27 is connected with the driving shaft 24 or the driven shaft 25 provided with an A-shaped flat key in a matching way through a key slot formed in the synchronous belt pulley;

the conveying belt wheels 416 are double-flange belt wheels arranged in pairs, the two pairs of double-flange belt wheels are respectively installed and fixed at two ends of the driving transmission shaft and the driven transmission shaft, the conveying belts 417 are correspondingly arranged in two, and each conveying belt 417 is respectively tensioned on the corresponding group of driving belt wheels and the corresponding driven belt wheels.

Preferably, the width of the belt groove 281 is 15 to 400 times of the diameter of the powder particles, and the depth is 3 to 100 times of the diameter of the powder particles; in practical use, the range can be further optimized and reduced, taking 316L stainless steel as an example, the diameter of the powder particles is 13-56um, and then the width of the belt groove 281 can be set to 3mm +/-2 mm, and the depth can be set to 0.6mm +/-0.4 mm.

Preferably, the driving shaft 24 is rotatably mounted on the pair of supports 23 through a deep groove ball bearing, the output shaft of the powder falling stepping motor 26 is fixedly connected with the driving shaft 24 and the output end of the driving transmission shaft and the output end of the transportation motor 415 through quincunx elastic couplings, and the powder storage bin 22 is fixedly connected with the support 21 through an inner hexagonal socket head cap screw.

Preferably, the installation flat plate 1 is also provided with a recovery hole 12, the residual powder collecting tank 5 is correspondingly arranged below the recovery hole 12 and is installed on the installation flat plate 1, and the recovery hole 12 is covered with a screen 13; a collecting plate 29 detachably matched with the powder storage bin 22 is arranged below the synchronous belt 28.

A control method of a double-material accurate powder laying device for an SLM is used for additive manufacturing, and comprises the following steps:

firstly, setting the number of the upper powder dropping mechanisms 2 according to actual needs, and filling sufficient metal powder of different types into the powder storage bin 22 of each upper powder dropping mechanism 2;

secondly, guiding the printed model into a computer, calculating the powder quantity required by one layer of additive manufacturing according to the powder quantitative conveying model, confirming that the powder quantity corresponds to the required quantity of the belt grooves 281, and then writing an MCU control program to input the MCU control program into a single chip microcomputer; during actual use, the single chip microcomputer is used for controlling the start, stop, rotating speed and rotating angle of the powder falling motor 26 and the conveying motor 415, and the start, stop and reversing of the linear actuator 426; the singlechip can be STM32 singlechip;

thirdly, the forming cylinder 6 is lifted to a distance which meets the set initial value distance with the scraper edge 425;

fourthly, the transport motor 415 drives the fixed supporting plate 424 to slide along the guide sliding rail 411 under the guide effect of the guide sliding block 412 through the transport belt wheel 416 and the transport belt 417 to drive the scraper mechanism 42 to move to the loading position, and meanwhile, the linear execution mechanism 426 drives the powder storage block 423 to slide in the sliding groove 4221 to the first station, so that the powder storage hole 4231 is communicated with the blanking hole 4211 and is positioned right below the discharging position of the specified one upper powder falling mechanism 2;

fifthly, the single chip microcomputer controls the powder dropping motor 26 to drive the synchronous belt 28 to rotate by a set angle at a set rotating speed, a set amount of powder is sent out from the powder storage bin 22 through the belt grooves 281 with a set number, and the powder falls into the powder storage hole 4231 through the material dropping hole 4211 at a material discharging position for temporary storage;

sixthly, the transportation motor 415 drives the scraper mechanism 42 to move to the printing position at the set transportation speed, so that the scraper mechanism 42 reaches the position above the edge of the forming cylinder 6;

seventh, the transport motor 415 drives the scraper mechanism 42 to move forward, so that the scraper mechanism 42 moves over the forming cylinder 6 at a set printing speed; in the process, the linear actuator 426 drives the powder storage block 423 to slide in the chute 4221 to a second station, so that the powder storage hole 4231 is communicated with the discharge hole 4222, the powder temporarily stored in the powder storage hole 4231 falls onto the forming cylinder 6 through the discharge hole 4222 and is uniformly spread under the action of the scraper blade 425;

step eight, sintering the designated area on the layer of powder by a laser system to finish the additive manufacturing of the layer;

and step nine, descending the forming cylinder 6 by the height of one step pitch, and then carrying out the next layer of additive manufacturing according to the method of the step four to the step eight until the additive manufacturing is finished.

Preferably, the powder quantitative conveying model is established as follows:

in the fifth step, the single chip microcomputer controls the powder dropping motor 26 to drive the synchronous belt 28 to rotate at a set rotating speed by a set angle, the set angle is such that the powder in n belt grooves 281 drops from the discharging position of the powder dropping mechanism 2, and n is determined according to the following formula:

wherein a is the side length of the square forming cylinder 6, d is the thickness of the powder required by single-layer additive manufacturing, and S is a safe supply coefficient.

As shown in fig. 8, if the side length of the square forming cylinder 6 is a and the thickness of the powder required for single-layer additive manufacturing is d, the amount of the powder required for single-layer additive manufacturing, i.e., one-time printing, is a ² d。

As shown in fig. 9, the length, width, and height of the belt groove 281 of the timing belt 28 are l, b, and h, respectively, and the amount of powder that can be theoretically conveyed per belt groove 281 is lbh.

Considering that the metal powder has strong fluidity, a small amount of metal powder leaks due to a small gap existing between the powder storage bin 22 and the synchronous belt 28, and the metal powder has certain viscosity under a high-temperature environment, so that the small amount of metal powder is adhered to the synchronous belt 28 and cannot be sent out, the actually sent powder amount is smaller than a theoretical value, and therefore, a safe supply coefficient S needs to be set to balance the difference.

The number n of discharged belt slots 281 then satisfies at each loading:

nalh＝Sa ² d；

in order to round the number of the belt grooves 281 as much as possible and to ensure a reasonable design, it is preferable that the length l of the belt grooves 281 is identical to the side length a of the forming cylinder 6, and there are:

nbh＝Sad；

namely:

in practical application, S is preferably 1.5, so that better additive manufacturing quality can be obtained.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. The utility model provides an accurate powder paving device of bimaterial for SLM, is including installing last powder mechanism (2) and the powder paving mechanism (4) that fall on installation flat board (1), set up shaping mouth (11) on the installation flat board (1), shaping jar (6) are corresponding to be located shaping mouth (11) department, its characterized in that:

powder feeding mechanism (2)

The powder storage bin (22) is fixedly arranged above the mounting flat plate (1) through a bracket (21), and the bottom of the powder storage bin is provided with a discharge hole (221); a pair of supports (23) are oppositely arranged and are fixedly arranged on the installation flat plate (1), and a driving shaft (24) and a driven shaft (25) are rotatably arranged on the pair of supports (23), and the axes of the driving shaft and the driven shaft are arranged in parallel; the powder falling stepping motor (26) is arranged on the support (23) or the mounting flat plate (1), and an output shaft of the powder falling stepping motor is fixedly connected with one end of the driving shaft (24); synchronous belt wheels (27) are fixedly arranged on the driving shaft (24) and the driven shaft (25), and a synchronous belt (28) is tensioned on the synchronous belt wheels (27) on the driving shaft (24) and the driven shaft (25); the synchronous belt (28) is positioned in the powder storage bin (22), one end of the synchronous belt is arranged at a position corresponding to the discharge hole (221), and strip-shaped belt grooves (281) are uniformly distributed on the outer surface of the synchronous belt (28);

powder laying mechanism (4)

The scraper mechanism (42) comprises an upper plate (421), a lower plate (422), a powder storage block (423), a fixed supporting plate (424), a scraper blade (425) and a linear actuating mechanism (426), wherein the upper plate (421) is provided with a long strip blanking hole (4211) matched with the discharge hole (221), the top surface of the lower plate (422) is provided with a sliding groove (4221), the bottom of the sliding groove is provided with a discharge hole (4222), the powder storage block (423) is arranged in the sliding groove (4221) in a sliding fit manner, and is provided with a long strip powder storage hole (4231);

the upper plate (421) is fixedly arranged at the top of the lower plate (422), the upper plate (421) and the lower plate (422) are arranged on the execution end of a conveying mechanism (41) through a fixing supporting plate (424), and the conveying mechanism (41) is used for driving a scraper mechanism (42) to do linear motion to and fro between the upper powder falling mechanism (2) and the forming cylinder (6);

the linear actuator (426) is fixedly arranged on the upper plate (421), the lower plate (422) or the fixed supporting plate (424), and the output end of the linear actuator is embedded into the sliding groove (4221) and is fixedly connected with the powder storage block (423); the linear actuating mechanism (426) is used for driving the powder storage block (423) to slide in the sliding groove (4221) to a first station where only the top of the powder storage hole (4231) is communicated with the blanking hole (4211) or a second station where only the bottom of the powder storage hole (4231) is communicated with the discharging hole (4222); the scraper edge (425) is fixedly mounted to the bottom of the lower plate (422).

2. The bi-material precision powder spreading device for SLM according to claim 1, characterized in that: the powder spreading device comprises at least two powder feeding and dropping mechanisms (2) which are arranged in the same direction along the linear motion direction.

3. The bi-material precision powder spreading device for the SLM as claimed in claim 2, wherein: the number of the blanking holes (4211) and the number of the powder storage holes (4231) are set corresponding to the number of the powder storage mechanisms (2), the number of the discharging holes (4222) is set corresponding to the number of the powder storage holes (4231) or is one less than the number of the powder storage holes (4231), each blanking hole (4211) and each powder storage hole (4231) are correspondingly arranged in parallel at intervals consistent with the intervals of synchronous belts (28) of each powder storage mechanism (2), and each discharging hole (4222) and each powder storage hole (4231) are arranged in an offset mode.

4. The bi-material precision powder spreading device for the SLM as claimed in claim 2, wherein: the conveying mechanism (41) comprises a pair of guide sliding rails (411) which are arranged in parallel, guide sliding blocks (412) are connected to the guide sliding rails (411) in a sliding fit mode, and the guide sliding blocks (412) serve as execution ends of the conveying mechanism (41) and are correspondingly installed and fixed with the fixed supporting plate (424);

two pairs of transportation supports (413) are respectively oppositely arranged at two ends of two guide sliding rails (411), two transportation transmission shafts (414) are arranged in parallel and are respectively and rotatably installed on the two pairs of transportation supports (413), any one of the two transmission shafts (414) is used as a driving transmission shaft, the other one of the two transmission shafts is used as a driven transmission shaft, and one end of the driving transmission shaft is fixedly connected with the output end of a transportation motor (415) which is fixedly installed;

the transmission device is characterized in that conveying belt wheels (416) serving as a driving belt wheel and a driven belt wheel are respectively and fixedly arranged on the driving transmission shaft and the driven transmission shaft, conveying belts (417) are tensioned on the driven belt wheels and the driving belt wheels, conveying belt pressing sheets (418) are arranged on the conveying belts (417), and the conveying belt pressing sheets (418) are fixedly connected with corresponding fixed supporting plates (424).

5. The bi-material precision powder spreading device for the SLM as claimed in claim 2, wherein: the synchronous belt wheel (27) is a single-flange synchronous belt wheel, and the synchronous belt wheel (27) is connected with a driving shaft (24) or a driven shaft (25) provided with an A-shaped flat key in a matching way through a key slot formed in the synchronous belt wheel;

the conveying belt wheels (416) are double-flange belt wheels which are arranged in pairs, the two pairs of double-flange belt wheels are respectively installed and fixed to two ends of the driving transmission shaft and two ends of the driven transmission shaft, the conveying belts (417) are correspondingly arranged in two, and each conveying belt (417) is respectively tensioned and arranged on the corresponding group of driving belt wheels and the corresponding group of driven belt wheels.

6. The bi-material precision powder spreading device for the SLM as claimed in claim 2, wherein: the width of the belt groove (281) is 15-400 times of the diameter of the powder particles, and the depth is 3-100 times of the diameter of the powder particles.

7. The bi-material precision powder spreading device for the SLM as claimed in claim 2, wherein: the powder storage device is characterized in that the driving shaft (24) is rotatably mounted on a pair of supports (23) through deep groove ball bearings, an output shaft of the powder falling stepping motor (26) is fixedly connected with the driving shaft (24) and an output end of the driving transmission shaft and an output end of the transportation motor (415) through quincunx elastic couplings, and the powder storage bin (22) is fixedly connected with the support (21) through an inner hexagonal socket head cap screw.

8. The bi-material precision powder spreading device for the SLM as claimed in claim 2, wherein: a recovery hole (12) is further formed in the mounting flat plate (1), the residual powder collecting tank (5) is correspondingly arranged below the recovery hole (12) and mounted on the mounting flat plate (1), and a screen plate (13) is arranged at the position of the recovery hole (12) in a covering mode; a collecting plate (29) detachably matched with the powder storage bin (22) and inserted is arranged below the synchronous belt (28).

9. A control method of a two-material precision powder laying apparatus for SLM, which is incremental manufactured using the two-material precision powder laying apparatus for SLM according to any one of claims 3 to 9, characterized by comprising the steps of:

firstly, setting the number of the powder feeding mechanisms (2) according to actual requirements, and filling sufficient metal powder of different types into a powder storage bin (22) of each powder feeding mechanism (2);

secondly, guiding the printed model into a computer, calculating the powder quantity required by one layer of additive manufacturing according to the powder quantitative conveying model, confirming that the powder quantity corresponds to the required quantity of the belt grooves (281), and then writing an MCU control program to input into a singlechip;

thirdly, the forming cylinder (6) is lifted until the distance between the forming cylinder and the scraper blade (425) meets the set initial value distance;

fourthly, a conveying motor (415) drives a fixed supporting plate (424) to slide along a guide sliding rail (411) under the guide effect of a guide sliding block (412) through a conveying belt wheel (416) and a conveying belt (417) to drive a scraper mechanism (42) to move to a loading position, and meanwhile a linear actuating mechanism (426) drives a powder storage block (423) to slide in a sliding groove (4221) to a first station, so that a powder storage hole (4231) is communicated with a blanking hole (4211) and is located right below the discharging position of an appointed upper powder-blanking mechanism (2);

fifthly, the singlechip controls a powder dropping motor (26) to drive a synchronous belt (28) to rotate by a set angle at a set rotating speed, a set amount of powder is sent out from a powder storage bin (22) through a set number of belt grooves (281), and the powder falls into a powder storage hole (4231) through a material dropping hole (4211) at a discharging position for temporary storage;

sixthly, the transport motor (415) drives the scraper mechanism (42) to move to the printing position at the set transport speed, so that the scraper mechanism (42) reaches the position above the edge of the forming cylinder (6);

seventhly, the transport motor (415) drives the scraper mechanism (42) to move forwards continuously, so that the scraper mechanism (42) moves over the forming cylinder (6) at a set printing speed; in the process, the linear actuating mechanism (426) drives the powder storage block (423) to slide in the sliding chute (4221) to a second station, so that the powder storage hole (4231) is communicated with the discharge hole (4222), the powder temporarily stored in the powder storage hole (4231) falls onto the forming cylinder (6) through the discharge hole (4222), and is uniformly spread under the action of the scraper blade (425);

and step nine, the forming cylinder (6) descends by the height of one step pitch, and then the next layer of additive manufacturing is carried out according to the method of the step four to the step eight until the additive manufacturing is finished.

10. The control method of the bi-material precise powder spreading device for the SLM according to claim 9, wherein the powder quantitative conveying model is established as follows:

in the fifth step, the singlechip controls a powder dropping motor (26) to drive a synchronous belt (28) to rotate at a set rotating speed by a set angle, the set angle is required to enable powder in n belt grooves (281) to drop from the discharging position of an upper powder dropping mechanism (2), and n is determined according to the following formula:

wherein a is the side length of the square forming cylinder (6), d is the thickness of powder required by single-layer additive manufacturing, and S is a safe supply coefficient.