CN115213436B

CN115213436B - Double-material accurate powder spreading device for SLM and control method thereof

Info

Publication number: CN115213436B
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: 2023-07-25
Anticipated expiration: 2042-07-22
Also published as: CN115213436A

Abstract

The utility model discloses a bi-material accurate powder spreading device for SLM and a control method thereof, relating to the technical field of additive manufacturing, comprising a plurality of powder falling mechanisms and powder spreading mechanisms which are arranged on a mounting flat plate, wherein a forming opening is formed on the mounting flat plate, and a forming cylinder is correspondingly arranged at the forming opening; the conveying mechanism of the powder spreading mechanism is used for driving the scraper mechanism of the powder spreading mechanism to do linear motion back and forth between the powder falling mechanism and the forming cylinder so as to realize powder spreading and feeding in additive manufacturing. The utility model receives and temporarily stores the metal powder supplied by the powder feeding mechanism at the loading position by the scraper mechanism, and then conveys the metal powder to the printing position corresponding to the forming cylinder for uniform tiling; multiple metal powders can be supplied through multiple powder feeding mechanisms, and additive manufacturing of multiple materials is realized without stopping; the powder feeding mechanism realizes quantitative supply of metal powder through the synchronous belt with the grooves, reduces waste of the metal powder, and reduces difficulty of cleaning work after additive manufacturing operation.

Description

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

Technical Field

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

Background

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

Additive manufacturing of metal materials is one of the most important components of additive manufacturing technology, and is the main research direction of advanced manufacturing technology. Additive manufacturing techniques include Binder Jetting (Binder Jetting), powder bed melting (Powder Bed Fusion), direct energy deposition (Directed Energy Deposition), lamination (Sheet extrusion), material Jetting (Material Jetting), photopolymerization (Vat Photopolymerization), and Material extrusion (Material Extrusion), and selective laser melting (Selective Laser Melting, SLM) which is one of the powder bed melting techniques suitable for additive manufacturing of metallic materials.

The material adding principle of the selective laser melting technology is that a sufficient amount of metal powder is put in a powder feeding cylinder in advance, a forming cylinder descends by a certain height during printing, meanwhile, the powder cylinder ascends by a certain height, a certain amount of powder uniformly falls out of the powder feeding cylinder onto the forming cylinder under the action of a scraper, then the moving track and the power intensity of laser are regulated by controlling a vibrating mirror, the metal powder in a selected area is melted, single-layer forming is completed, and the single-layer forming is repeated for a plurality of times, so that the required metal component can be obtained.

The existing selective laser melting technology can only realize the additive manufacturing of single materials, cannot meet the requirements of dual-material additive manufacturing, and can ensure that the manufacturing process is normally carried out only by adding a large amount of metal powder in advance before processing, so that a large amount of waste of raw materials is caused, and the cleaning workload after processing is also heavy.

By prior art search, there are the following known technical solutions:

prior art 1:

application number: CN202020712718.4, filing date: 2020.04.30, publication (bulletin) day: 2021.04.30 the utility model provides a powder spreading device for a multi-metal material, which comprises 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 congruent, the first material opening and the second material opening are rectangular, the second cover plate is arranged on the second material opening through two guide rails parallel to the short side 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 bracket to do reciprocating motion relative to the working platform. The powder spreading device disclosed by the utility model can be used for spreading different kinds of powder simultaneously; and the proportion of different kinds of metal powder is adjusted during powder laying.

The powder falling process in the prior art cannot be quantified, the quantity of the falling powder cannot be estimated, the powder can be adjusted empirically only through multiple shaking of the adjusting mechanism, the loss of raw materials is large, and the cleaning workload after processing is heavy.

Prior art 2:

application number: CN201020671362.0, filing date: 2010, 12.21, publication (bulletin) day: 2011.11.09 the utility model provides a selective laser sintering single-sided powder feeding device realized by adopting a powder return groove, which comprises a powder spreading roller, a powder feeding cylinder, a powder overflow cylinder and a powder return groove. The utility model saves equipment space, reduces equipment size, reduces equipment complexity, effectively reduces equipment cost, improves equipment reliability, and further meets SLS process requirements.

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

Through the above search, the above technical scheme does not affect the novelty of the utility model; and the above prior art combinations do not destroy the inventive aspects of the present utility model.

Disclosure of Invention

The utility model provides a dual-material precise powder spreading device for SLM and a control method thereof, which aims to avoid the defects of the prior art.

The utility model adopts the following technical scheme for solving the technical problems: the double-material precise powder spreading device for the SLM comprises a powder falling 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;

go up whitewashed mechanism that falls

The powder storage bin is fixedly arranged above the mounting plate through a bracket, and the bottom of the powder storage bin is provided with a discharge hole; the driving shaft and the driven shaft are rotatably mounted on the pair of the supports, and the axes of the driving shaft and the driven shaft are parallel; the powder falling stepping motor is arranged on the support or the mounting plate, and an output shaft of the powder falling stepping motor is fixedly connected with one end of the driving shaft; the driving shaft and the driven shaft are fixedly provided with synchronous pulleys, and the synchronous belts are tensioned on the synchronous pulleys 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 the outer surface of the synchronous belt is uniformly provided with strip-shaped grooves;

powder spreading mechanism

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

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 a fixed supporting plate, and the conveying mechanism is used for driving the scraper mechanism to do linear movement back and forth between the powder feeding mechanism and the forming cylinder;

the linear actuating mechanism is arranged and fixed 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 sliding groove 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 chute to a first station in which only the top of the powder storage hole is communicated with the blanking hole or a second station in which only the bottom of the powder storage hole is communicated with the discharging hole; the doctor blade is mounted and secured to the bottom of the lower plate.

Further, the powder spreading device comprises at least two powder falling mechanisms which are arranged in the same direction along the linear motion direction.

Further, the number of the blanking holes and the powder storage holes is set corresponding to the number of the powder falling mechanisms, the number of the discharging holes is set corresponding 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 synchronous belts of the powder falling mechanisms, and the discharging holes and the powder storage holes are arranged in an offset mode.

Further, the conveying mechanism comprises a pair of parallel guide sliding rails, the guide sliding rails are connected with guide sliding blocks in a sliding fit manner, and the guide sliding blocks serve as execution ends of the conveying mechanism and are correspondingly installed and fixed with the fixed supporting plates;

the two pairs of conveying supports are respectively opposite to the two ends of the two guide sliding rails, the two conveying transmission shafts are arranged in parallel and are respectively rotatably mounted on the two pairs of conveying supports, any one of the two conveying transmission shafts is used as a driving transmission shaft, the other conveying 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 the conveying motor which is fixedly mounted;

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

Furthermore, 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 way through a key slot formed in the synchronous belt pulley;

the conveyer belt wheels are double flange belt wheels arranged in pairs, 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 conveyer belts are correspondingly arranged in two, and each conveyer belt is respectively tensioned and arranged on a corresponding group of driving belt wheels and driven belt wheels.

Further, the width of the groove 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.

Further, the driving shaft is rotatably mounted on a pair of supports through a deep groove ball bearing, the output shaft of the powder falling stepping motor is fixedly connected with the driving shaft and the output end of the driving transmission shaft and the output end of the conveying motor through a quincuncial elastic coupling, and the powder storage bin is fixedly connected with the support through an inner hexagonal cylindrical head screw.

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

A control method of a bi-material precise powder spreading device for an SLM (selective laser deposition) comprises the following steps:

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

secondly, leading 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 the quantity of the required belt grooves corresponding to the powder quantity, and then writing an MCU control program and inputting the MCU control program into a singlechip;

thirdly, the forming cylinder is lifted to a distance from the scraper blade to meet a preset initial value;

a transportation motor drives a fixed supporting plate to slide along a guide sliding rail under the guide action of a guide sliding block through a transportation belt wheel and a transportation belt, so that a scraper mechanism is driven to move to a loading position, and meanwhile, a linear actuating mechanism drives a powder storage block to slide in a sliding groove to a first station, so that a powder storage hole is communicated with a blanking hole and is positioned right below a discharging position of a specified powder feeding mechanism;

fifthly, the singlechip controls the powder falling motor to drive the synchronous belt to rotate by a set angle at a set rotating speed, a set amount of powder is sent out from the powder storage bin through a set number of belt grooves, and falls into the powder storage hole from the discharging position for temporary storage through the blanking hole;

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;

seventh, the transport motor drives the scraper mechanism to move forwards continuously, so that the scraper mechanism moves above 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 a second station, so that the powder storage hole is communicated with the discharging hole, and powder temporarily stored in the powder storage hole falls onto the forming cylinder through the discharging hole and is uniformly spread under the action of the scraper blade;

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

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

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

in the fifth step, the single chip microcomputer controls the powder falling motor to drive the synchronous belt to rotate by a set angle at a set rotating speed, the set angle enables the powder in n belt grooves to fall out from the discharging position of the powder falling mechanism, and n is determined according to the following formula:

wherein a is the side length of a square forming cylinder, d is the thickness of powder required by single-layer additive manufacturing, and S is a safety supply coefficient. The utility model provides a bi-material accurate powder spreading device for an SLM and a control method thereof, which have the following beneficial effects:

1. according to the utility model, the scraper mechanism is driven by the conveying mechanism to reciprocate between the powder falling mechanism and the forming cylinder, the metal powder supplied by the powder falling mechanism is received and temporarily stored at a loading position corresponding to the powder falling mechanism by the scraper mechanism, and then the metal powder is conveyed to a printing position corresponding to the forming cylinder to be uniformly spread; the powder feeding mechanism realizes quantitative supply of metal powder through the synchronous belt with the grooves, reduces the waste of the metal powder and reduces the difficulty of cleaning work after additive manufacturing operation;

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

3. according to the utility model, the powder storage block of the scraper mechanism can block metal powder from falling out in a first station state and realize metal powder discharging in a 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, so that the feeding stroke of a scraper in the non-forming area is reduced, and the efficiency of additive manufacturing is further improved;

4. the utility model adopts a symmetrical structure form, thereby improving the space utilization rate.

Drawings

FIG. 1 is a schematic diagram of the structure of the present utility model;

FIG. 2 is a schematic diagram of the powder falling mechanism of the present utility model;

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

FIG. 4 is a schematic view of the structure of the powder storage bin of the utility model;

FIG. 5 is a schematic view of the synchronous belt according to the present utility model;

FIG. 6 is a schematic diagram of an assembled structure of a synchronous belt, a driving shaft and a driven shaft of the present utility model;

FIG. 7 is a schematic view of the doctor blade mechanism of the present utility model;

FIG. 8 is a schematic view of the structure of the forming cylinder of the present utility model;

fig. 9 is a schematic view of the structure of the lower plate of the present utility model.

In the figure:

1. mounting a flat plate, 11, a forming port, 12, a recovery hole, 13 and a screen plate; 2. the powder feeding and discharging mechanism comprises a powder feeding mechanism, 21, a bracket, 22, a powder storage bin, 221, a discharge hole, 23, a support, 24, a driving shaft, 25, a driven shaft, 26, a powder feeding motor, 27, a synchronous pulley, 28, a synchronous belt, 281, a belt groove, 29 and a collecting plate; 4. the powder spreading mechanism 41, the conveying mechanism 411, the guide sliding rails 412, the guide sliding blocks 413, the conveying support seats 414, the conveying transmission shafts 415, the conveying motors 416, the conveying belt wheels 417, the conveying belts 418 and the conveying belt pressing sheets; 42. the scraper mechanism 421, the upper plate, 4211, the blanking hole, 422, the lower plate, 4221, the chute, 4222, the discharging hole, 423, the powder storage block, 4231, the powder storage hole, 424, the fixed supporting plate, 425, the scraper blade, 426 and the linear executing mechanism; 5. a residual powder collecting tank; 6. and (5) forming a cylinder.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions in the embodiments of the present utility model will be clearly and completely described in the following in conjunction with the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

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

go up whitewashed mechanism 2

The powder storage bin 22 is fixedly arranged above the mounting 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, are fixedly arranged on the mounting 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 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; the driving shaft 24 and the driven shaft 25 are provided with a synchronous pulley 27, and a synchronous belt 28 is tensioned on the synchronous 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 at a position corresponding to the discharge hole 221, and the outer surface of the synchronous belt 28 is uniformly provided with various strip-shaped grooves 281;

powder spreading 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 executing mechanism 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 chute 4221, the bottom of the chute is provided with a discharge hole 4222, the powder storage block 423 is arranged in the chute 4221 in a sliding fit manner, and the upper plate is provided with a strip-shaped powder storage hole 4231;

the upper plate 421 is fixed on top of the lower plate 422, the upper plate 421 and the lower plate 422 are mounted on the actuating end of the transport mechanism 41 through the fixing supporting plate 424, and the transport mechanism 41 is used for driving the scraper mechanism 42 to do linear movement back and forth between the powder feeding mechanism 2 and the forming cylinder 6;

the linear actuating mechanism 426 is fixed 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 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 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; the scraping blade 425 is mounted and fixed to the bottom of the lower plate 422.

Preferably, the powder spreading device comprises at least two powder falling 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 storage holes 4231 is set corresponding to the number of the powder falling mechanisms 2, the number of the discharging holes 4222 is set corresponding to the number of the powder storage holes 4231 or one less than the number of the powder storage holes 4231, the blanking holes 4211 and the powder storage holes 4231 are correspondingly arranged in parallel at a distance consistent with the distance between the synchronous belts 28 of the powder falling mechanisms 2, and the discharging holes 4222 and the powder storage holes 4231 are arranged in a bias way; each powder storage hole 4231 can slide to a first station communicated with only one corresponding blanking hole 4211 at the top of the powder storage hole or a second station communicated with only one corresponding discharging hole 4222 at the bottom of the powder storage hole under the drive of a linear executing mechanism 426; under this setting, when scraper mechanism 42 is located the loading position, every group stores powder hole 4231 and blanking hole 4211 and corresponds and be located the ejection of compact position under an upper powder mechanism 2 respectively, can make scraper mechanism 42 carry out the loading of different kinds of metal powder when being located same loading position all the time, does benefit to the simplification of programming.

Preferably, the transport mechanism 41 comprises a pair of parallel guide slide rails 411, the guide slide rails 411 are connected with guide slide blocks 412 in a sliding fit manner, and the guide slide blocks 412 and the guide slide rails 411 form a sliding pair along the guide slide rails 411; the guide slide block 412 is used as an execution end of the transport mechanism 41 and is correspondingly installed and fixed with the fixed supporting plate 424;

two pairs of conveying supports 413 are respectively opposite to two ends of the two guide slide rails 411, two conveying transmission shafts 414 are arranged in parallel and are respectively rotatably mounted on the two pairs of conveying supports 413, any one of the two conveying transmission shafts 414 is used as a driving transmission shaft, the other conveying 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 conveying motor 415 which is fixedly mounted;

the driving transmission shaft and the driven transmission shaft are respectively provided with a conveying belt pulley 416 serving as a driving belt pulley and a driven belt pulley, a conveying belt 417 is tensioned and arranged on the driven belt pulley and the driving belt pulley, 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 fixing supporting plate 424.

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

the conveying belt wheels 416 are double-flange belt wheels arranged in pairs, 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 and arranged on a corresponding group of driving belt wheels and driven belt wheels.

Preferably, the width of the groove 281 is 15-400 times the diameter of the powder particles, and the depth is 3-100 times the diameter of the powder particles; in practical use, the range can be further optimized and reduced, for example, the 316L stainless steel has a powder particle diameter of 13-56um, and the width of the groove 281 can be 3mm plus or minus 2mm, and the depth can be 0.6mm plus or minus 0.4mm.

Preferably, the driving shaft 24 is rotatably mounted on a pair of supports 23 through deep groove ball bearings, 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 conveying motor 415 through plum blossom-shaped elastic couplings, and the powder storage bin 22 is fixedly connected with the support 21 through hexagon socket head cap screws.

Preferably, the mounting 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 mounted on the mounting flat plate 1, and the recovery hole 12 is covered with a screen 13; a collecting plate 29 which is detachably matched and inserted with the powder storage bin 22 is arranged below the synchronous belt 28.

A control method of a bi-material precise powder paving device for an SLM (selective laser sintering) uses the powder paving device to perform additive manufacturing, and comprises the following steps:

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

secondly, leading 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 the quantity of the required grooves 281 corresponding to the powder quantity, and then writing an MCU control program and inputting the MCU control program into a singlechip; in actual use, the singlechip is used for controlling the start and stop, the rotating speed and the rotating angle of the powder falling motor 26 and the conveying motor 415, and the start and stop and the reversing of the linear executing mechanism 426; the singlechip can be an STM32 singlechip;

third, the forming cylinder 6 is raised to a distance from the scraping blade 425 satisfying a set initial value;

fourth, the transportation motor 415 drives the fixed supporting plate 424 to slide along the guiding sliding rail 411 under the guiding action of the guiding sliding block 412 through the transportation belt pulley 416 and the transportation belt 417, so as to drive the scraper mechanism 42 to move to the loading position, and meanwhile, the linear executing 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 of the powder falling mechanisms 2;

fifthly, the singlechip controls the powder falling 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 a set number of belt grooves 281, and falls into the powder storage hole 4231 at a discharging position for temporary storage through the blanking hole 4211;

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

seventh, the transport motor 415 drives the doctor mechanism 42 to continue to move forward, so that the doctor 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 chute 4221 to a second station, so that the powder storage hole 4231 is communicated with the discharge hole 4222, and 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 nine, the forming cylinder 6 descends by one step distance, and then the next layer of additive manufacturing is carried out according to the methods from the step four to the step eight until the additive manufacturing is completed.

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

in the fifth step, the single chip microcomputer controls the powder falling motor 26 to drive the synchronous belt 28 to rotate by a set angle at a set rotation speed, the set angle should enable the powder in the n belt grooves 281 to fall out from the discharging position of the powder falling mechanism 2, and n is determined according to the following formula:

where a is the side length of the square forming cylinder 6, d is the thickness of the powder required for single layer additive manufacturing, and S is the safety supply coefficient.

As shown in fig. 8, the side length of the square forming cylinder 6 is a, and powder required by single-layer additive manufacturing is manufacturedThe thickness of the powder is d, and the amount of 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 grooves 281 of the timing belt 28 are l, b, and h, respectively, and the amount of powder that each belt groove 281 can theoretically deliver is lbh.

Considering that the metal powder has strong fluidity, the existence of a small gap between Chu Fencang and the timing belt 28 causes a small amount of metal powder to leak, and the metal powder has a certain viscosity in a high temperature environment to cause a small amount of metal powder to adhere to the timing belt 28 and not be delivered, the amount of powder actually delivered is smaller than the theoretical value, and therefore a safe supply coefficient S needs to be set to balance the difference.

The number n of discharged slots 281 per loading is then:

nalh＝Sa ² d；

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

nbh＝Sad；

namely:

in practical applications, S is preferably 1.5, which can obtain better additive manufacturing quality.

It is noted that relational terms such as first and second, and the like are 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. Moreover, 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 phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; although the utility model 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 scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims

1. A dual material accurate shop powder device for SLM, including installing on the dull and stereotyped (1) of installation go up whitewashed mechanism (2) and shop powder mechanism (4), set up shaping mouth (11) on the dull and stereotyped (1) of installation, shaping jar (6) are located correspondingly shaping mouth (11) department, its characterized in that:

upper falling powder mechanism (2)

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

powder spreading 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 strip-shaped blanking hole (4211) matched with the discharge hole (221), the top surface of the lower plate (422) is provided with a chute (4221), the bottom of the chute is provided with a discharge hole (4222), and the powder storage block (423) is arranged in the chute (4221) in a sliding fit manner, and is provided with a strip-shaped powder storage hole (4231);

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

the linear actuating mechanism (426) is arranged and fixed 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 sliding groove (4221) and is connected and fixed with the powder storage block (423); the linear actuating mechanism (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); the doctor blade (425) is mounted and secured to the bottom of the lower plate (422).

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

3. The bi-material accurate powder spreading device for SLM according to claim 2, characterized in that: the blanking holes (4211) and the powder storage holes (4231) are arranged corresponding to the powder falling mechanisms (2), the discharging holes (4222) are arranged corresponding to the powder storage holes (4231) or one less than the powder storage holes (4231), the blanking holes (4211) and the powder storage holes (4231) are arranged in parallel and are arranged in a corresponding and parallel mode at a distance consistent with the synchronous belt (28) distance of the powder falling mechanisms (2), and the discharging holes (4222) and the powder storage holes (4231) are arranged in a biased mode.

4. The bi-material accurate powder spreading device for SLM according to claim 2, characterized in that: the conveying mechanism (41) comprises a pair of parallel guide slide rails (411), the guide slide rails (411) are connected with guide slide blocks (412) in a sliding fit manner, and the guide slide blocks (412) serve as execution ends of the conveying mechanism (41) and are correspondingly installed and fixed with the fixed supporting plates (424);

the two pairs of conveying supports (413) are respectively arranged at two ends of the two guide sliding rails (411) in a opposite mode, two conveying transmission shafts (414) are arranged in parallel and are respectively rotatably mounted on the two pairs of conveying supports (413), any one of the two conveying transmission shafts (414) is used as a driving transmission shaft, the other conveying 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 conveying motor (415) which is fixedly mounted;

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

5. The bi-material accurate powder spreading device for SLM according to claim 4, characterized in that: the synchronous pulley (27) is a single-flange synchronous pulley, and the synchronous pulley (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 pulley;

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

6. The bi-material accurate powder spreading device for SLM according to claim 2, characterized in that: the width of the 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 accurate powder spreading device for SLM according to claim 2, 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 conveying motor (415) through a plum blossom-shaped elastic coupling, and the powder storage bin (22) is fixedly connected with the support (21) through inner hexagonal cylindrical head screws.

8. The bi-material accurate powder spreading device for SLM according to claim 2, characterized in that: the installation plate (1) is also provided with a recovery hole (12), the residual powder collection tank (5) is correspondingly arranged below the recovery hole (12) and is installed on the installation plate (1), and a screen plate (13) is covered at the recovery hole (12); a collecting plate (29) which is detachably matched with the powder storage bin (22) and inserted is arranged below the synchronous belt (28).

9. A control method of a bi-material accurate powder spreading device for SLM, which is used for incremental manufacturing according to any one of claims 3 to 8, characterized by comprising the steps of:

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

secondly, leading the printed model into a computer, calculating the powder amount required by one layer of additive manufacturing according to the powder quantitative conveying model, confirming the amount of required grooves (281) corresponding to the powder amount, and then writing an MCU control program and inputting the MCU control program into a singlechip;

thirdly, the forming cylinder (6) is lifted to a distance from the scraper blade (425) meeting a set initial value;

a transportation motor (415) drives a fixed supporting plate (424) to slide along a guide sliding rail (411) under the guide action of a guide sliding block (412) through a transportation belt wheel (416) and a transportation belt (417), a scraper mechanism (42) is driven to move to a loading position, and 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 positioned right below a discharging position of a specified powder falling mechanism (2);

fifthly, the singlechip controls the powder falling 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 Chu Fencang (22) through a set number of belt grooves (281), and falls into the powder storage hole (4231) from the discharging position for temporary storage through the blanking hole (4211);

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

seventh, the transport motor (415) drives the scraper mechanism (42) to move forwards, so that the scraper mechanism (42) moves above 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 chute (4221) to a second station, so that the powder storage hole (4231) is communicated with the discharge hole (4222), and 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 one step distance, and then the next layer of additive manufacturing is carried out according to the methods from the step four to the step eight until the additive manufacturing is completed.

10. The control method of a bi-material accurate powder spreading device for SLM according to claim 9, characterized in that said powder quantitative transfer model is established as follows:

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

n=(adS)/(bh)；

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