CN117399648A - Powder bed additive manufacturing equipment and method for hollow thin-wall part - Google Patents

Abstract

The invention discloses a device and a method for manufacturing a powder bed additive of a hollow thin-wall part, wherein the device comprises a part forming chamber and a scanner, a forming cylinder and powder supply cylinders are arranged in the part forming chamber, a forming lifting table for supporting the powder bed is arranged in the forming cylinder, a powder spreading device for horizontally pushing powder in the powder supply cylinders onto a forming baseplate of the forming lifting table to form the powder bed is also arranged in the part forming chamber, a forming cavity is formed between the inner constraint and the outer constraint in a surrounding manner, the forming lifting table is arranged in the forming cavity in a sliding manner in a matching manner, a tiny gap is kept between the hollow thin-wall part and the inner wall and the outer wall of the forming cavity after the hollow thin-wall part is printed and formed, the number of the two powder supply cylinders is two, the two powder supply cylinders are oppositely arranged at two sides of the forming cylinder along the powder spreading direction, the powder spreading directions of the two powder spreading devices are opposite, and powder is alternately spread.

Description

Powder bed additive manufacturing equipment and method for hollow thin-wall part

Technical Field

The invention belongs to the field of additive manufacturing, and particularly relates to hollow thin-wall part powder bed additive manufacturing equipment and method.

Background

The powder bed melting technology is a common method in metal additive manufacturing and forming, and comprises a selective laser melting technology and a selective electron beam melting technology, wherein the two technologies are mainly different in heat source, the selective laser melting technology uses a fiber laser as a heat source, and the selective electron beam melting technology uses a high-energy electron beam as a heat source. As shown in fig. 1, the principle of the powder bed melting technology is that metal powder is used as a processing raw material, a powder spreading roller/brush firstly flatly pushes the metal powder from a powder supply cylinder to a substrate of a forming cylinder, an energy beam selectively melts the powder on the substrate according to a planned path to process a current layer, then a lifting table drives the substrate to descend by a layer thickness distance, the powder supply cylinder ascends by a certain thickness distance, and then the metal powder is spread on the processed current layer by the powder spreading roller/brush. The equipment is adjusted into the data printed on the lower layer for processing, and the processing is performed layer by layer until the whole part is processed. The powder bed fusion technology has unique advantages in the aspects of personalized design, complex structure integrated forming and the like, and is widely applied to the fields of aerospace, biomedical treatment, nuclear industry and the like.

However, to print out a complete part, the powder stock must be filled to a certain height in the forming cylinder, and for some large non-solid, thin-walled parts, the powder required is much larger than the volume of the formed part, resulting in a significant waste of raw material. Although part of the powder can be used for recycling, the recycling of the powder brings adverse factors such as impurities, oxygenation, reduction of sphericity and fluidity of the powder, and the like, and has the consequences of high manufacturing cost of the additive, poor performance stability and the like. For example, a powder bed 3D printing apparatus of 1200mm×600mm×1500mm is used to prepare a GH4169 part with a height of about 1.5m and 200kg, and a single use of > 4 tons of powder is required, the raw material input cost exceeds 200 ten thousand, the powder utilization rate is less than 5%, and the problem that only a small part of powder is utilized during the part forming process is also a major obstacle that the powder bed fusion technology is difficult to be widely applied further.

Disclosure of Invention

The invention mainly aims to provide equipment and a method for manufacturing a hollow thin-wall part powder bed additive, which greatly reduce unnecessary powder filling in a forming cylinder and save powder investment and raw material cost by adopting a powder constraint and bidirectional alternate powder laying mode.

To this end, the invention provides a hollow thin-wall part powder bed additive manufacturing device, which comprises a part forming chamber and a scanner, wherein a forming cylinder and a powder supply cylinder are arranged in the part forming chamber, a forming lifting table for supporting a powder bed is arranged in the forming cylinder, a powder laying device for horizontally pushing powder in the powder supply cylinder onto a forming substrate of the forming lifting table to form the powder bed is also arranged in the part forming chamber, and the scanner is used for enabling an energy beam to sweep through the powder bed to enable the powder to be melted;

the forming cylinder is internally provided with an inner constraint and an outer constraint, a forming cavity is formed between the inner constraint and the outer constraint in a surrounding mode, the forming cavity is arranged in the forming cylinder in a matching mode, the upper surface of the forming cavity is flush with the upper surface of the forming cylinder, the forming lifting table is arranged in the forming cavity in a matching sliding mode, and a tiny gap is kept between the hollow thin-wall piece and the inner wall and the outer wall of the forming cavity after the hollow thin-wall piece is printed and formed;

the powder feeding cylinders are arranged in two, each powder feeding cylinder is provided with one powder paving device, the two powder feeding cylinders are oppositely arranged on two sides of the forming cylinder along the powder paving direction, and the powder paving directions of the two powder paving devices are opposite and are used for alternately paving powder.

Specifically, the powder spreading device comprises a powder spreading roller/brush and a horizontal moving mechanism for driving the powder spreading roller/brush to horizontally move along the powder spreading direction.

Specifically, the forming cylinder is also provided with a lifting mechanism which drives the inner constraint and the outer constraint to move up and down in the forming cylinder, and the upper ends of the inner constraint and the outer constraint can be kept flush with the forming lifting table under the driving of the lifting mechanism.

Specifically, the lifting mechanism comprises two lifting rods which are independently connected with the inner constraint and the outer constraint.

Specifically, the powder supply cylinder comprises a cylinder body and a pushing plug which is arranged in the cylinder body and drives powder to move upwards.

In particular, a ventilation system for evacuating and/or filling a gas in the part forming chamber is also included.

Specifically, the hollow thin-wall part is an aero-engine casing.

Specifically, the energy beam is a laser beam or an electron beam.

Specifically, the manufacturing materials of the forming substrate, the inner constraint and the outer constraint are the same.

In another aspect, the present application provides a method for manufacturing a powder bed additive of a hollow thin-walled member, including the steps of:

firstly, preparing metal powder, and filling the powder into a powder supply cylinder;

designing a forming lifting table according to the size and structural characteristics of the part, installing a forming substrate on the forming lifting table, flatly pushing metal powder onto the forming substrate of a forming cylinder by a powder spreading device, flatly spreading the rest powder into a powder supply cylinder on the opposite side, and melting the powder on the substrate by an energy beam according to a planned path to process a current layer;

thirdly, driving the forming baseplate to descend by a layer thickness distance by the forming lifting table, lifting the other powder supply cylinder by a certain thickness distance, paving metal powder on the processed current layer by the other powder paving device, and paving the rest powder into the powder supply cylinder at the opposite side;

and fourthly, transferring the data printed on the lower layer into the equipment to melt the powder, and processing the powder layer by layer until the whole part is processed.

Compared with the prior art, the invention has the following beneficial effects: through the mode of powder constraint and bidirectional alternate powder spreading, unnecessary powder spreading in a forming cylinder of the powder bed additive manufacturing equipment can be greatly reduced, powder investment and raw material cost are saved, a large amount of circulating powder can be avoided, the amount of powder required for printing is greatly reduced, and the size and occupied space of the equipment can be reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a prior art powder bed additive manufacturing apparatus;

FIG. 2 is a front view of a hollow thin-walled member powder bed additive manufacturing apparatus provided by an embodiment of the present invention;

FIG. 3 is a side view of a hollow thin-walled member powder bed additive manufacturing apparatus provided by an embodiment of the present invention;

wherein: 1. a part forming chamber; 2. a scanner; 3. a forming cylinder; 4. a powder supply cylinder; 401. a cylinder; 402. pushing the plug; 5. a powder bed; 6. a forming lifting table; 7. forming a substrate; 8. a powder spreading device; 9. internal restraint; 10. external restraint; 11. a molding cavity; 12. a hollow thin-walled member; 13. a lifting rod; 14. a ventilation system.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

Referring to fig. 2 and 3, an additive manufacturing apparatus for a powder bed 5 of a hollow thin-walled member 12 includes a part forming chamber 1 and a scanner 2, a forming cylinder 3 and a powder supply cylinder 4 are provided in the part forming chamber 1, a forming lift table 6 for supporting the powder bed 5 is provided in the forming cylinder 3, a powder laying device 8 for horizontally pushing powder in the powder supply cylinder 4 onto a forming substrate 7 of the forming lift table 6 to form the powder bed 5 is provided in the part forming chamber 1, and the scanner 2 is used for sweeping an energy beam across the powder bed 5 to melt the powder.

Wherein, the forming cylinder 3 is also provided with an inner constraint 9 and an outer constraint 10, the outer constraint 10 is installed in the forming cylinder 3 in a matching way, a forming cavity 11 is enclosed between the outer constraint 10 and the inner constraint 9, the upper surface of the forming cavity 11 is flush with the upper surface of the forming cylinder 3, the forming lifting table 6 is installed in the forming cavity 11 in a matching sliding way, the forming baseplate 7 is placed on the forming lifting table 6, the hollow thin-wall part 12 keeps a tiny gap with the inner wall and the outer wall of the forming cavity 11 after being printed and formed, the number of the powder supply cylinders 4 is two, each powder supply cylinder 4 is provided with one powder spreading device 8, the two powder supply cylinders 4 are oppositely arranged at two sides of the forming cylinder 3 along the powder spreading direction, and the two powder spreading devices 8 above the two powder supply cylinders 4 are capable of spreading the powder of a certain proportion in the corresponding powder supply cylinders 4 on the forming baseplate 7 uniformly, compacting the powder bed 5, and spreading the rest powder on the surface of the opposite side powder supply cylinders 4 along the powder spreading direction of the powder supply cylinders 4.

When the additive manufacturing equipment is used for printing the hollow thin-wall part 12, firstly, metal powder is prepared, the powder is divided equally into two powder supply cylinders 4, a forming lifting table 6 is designed according to the size and structural characteristics of a part, a forming substrate 7 is arranged on the forming lifting table 6, one powder spreading device 8 firstly pushes the metal powder onto the forming substrate 7 of the forming cylinder 3 in a flat way, then the rest powder is spread into the powder supply cylinder 4 at the opposite side, and the powder on the substrate is melted in a selected area of a path planned by an energy beam to process the current layer; then the molding lifting table 6 drives the molding substrate 7 to descend by a layer thickness distance, the other powder supply cylinder 4 ascends by a certain thickness distance, the other powder spreading device 8 spreads metal powder on the processed current layer, then the rest powder is spread in the powder supply cylinder 4 on the opposite side, the equipment is adjusted into the data printed on the lower layer to melt the powder, and the process is repeated in this way, so that layer-by-layer processing is realized until the whole part is processed.

According to the method, the lifting table of the existing powder bed 5 material-increasing manufacturing equipment is improved, a set of powder supply system is added, the rest parts of the existing powder bed 5 material-increasing manufacturing equipment are designed according to the size and structural characteristics of parts, and constraint is added on the inner side and the outer side of the forming lifting table 6 of the forming cylinder 3, so that the powder carrying quantity of the powder bed 5 is greatly reduced, the constrained size only needs to ensure that the hollow thin-wall part 12 subjected to printing forming is not contacted with the hollow thin-wall part, the distance between the hollow thin-wall part 12 and the inner side wall and the outer side wall of the forming cavity 11 can be kept between 2mm and 6mm, and the size of the specific distance can be adjusted adaptively according to the size of a printed part, so that unnecessary powder spreading in the forming cylinder 3 of the powder bed 5 material-increasing manufacturing equipment is greatly reduced, and the powder investment and the raw material cost are saved.

In addition, through two powder supply jar 4 of symmetrical arrangement to utilize two powder devices 8 that shop that work in turn to realize shop's powder, and accomplish the tiling of powder in another powder supply jar 4 that remains in the shop's powder in-process, can avoid a large amount of circulating powder to produce from this, print required powder volume and reduce by a wide margin, can reduce the size and the occupation space of equipment.

Referring to fig. 2 and 3, the inner bottom surface of the part forming chamber 1 is concaved inwards to form a forming cylinder 3 and a cylinder body 401 of the powder supply cylinder 4, the inner bottom surface of the part forming chamber 1 directly forms a powder paving plane of the powder paving device 8, and two ends of the powder paving roller are respectively abutted with two side walls of the part forming chamber 1 parallel to the powder paving direction.

It will be appreciated that in the actual printing process, in order to spread the remaining powder as much as possible to form a powder bed layer in the opposite side powder supply cylinder, the thickness formed after the remaining powder is spread in the powder supply cylinder 4 is calculated according to the volume of the remaining powder after each powder spreading and the cross-sectional area of the powder supply cylinder 4 at the opposite side, so as to guide the action of the powder supply cylinder 4, and here, for convenience in explaining the powder spreading process, the two powder supply cylinders 4 are named as a first powder supply cylinder and a second powder supply cylinder.

When the first powder supply cylinder 4 supplies powder, the powder in the first powder supply cylinder moves upwards to enable the powder in the powder supply cylinder 4 to exceed the forming cylinder 3 by a certain height, meanwhile, the inner powder of the second powder supply cylinder moves downwards by a set distance, the powder spreading device 8 of the first powder supply cylinder firstly pushes the metal powder exceeding the upper surface of the forming cylinder 3 towards the forming cylinder 3 in a flat way, part of the powder is uniformly spread on the forming substrate 7 of the forming cavity 11, and the rest of the powder is spread into the second powder supply cylinder at the opposite side along with the continuous forward movement of the powder spreading device 8;

the distance of the powder in the second powder supply cylinder moving downwards is determined according to the amount of the powder remained by the powder paving device 8 of the first powder supply cylinder, so that the stability of the powder amount can be ensured each time after the powder remained by paving is just flatly paved in the second powder supply cylinder for one layer, and the upper surface of the powder in the second powder supply cylinder is basically flush with the upper surface of the forming cylinder 3. In the same way, the descending height of the powder in the first powder supply cylinder 4 and the lifting height of the powder in the second powder supply cylinder 4 can be correspondingly adjusted in the powder supply process of the second powder supply cylinder.

In some embodiments, the powder spreading device 8 and the powder supplying cylinder 4 are all of existing structures, for example, the powder spreading device 8 includes a powder spreading roller, a rotating mechanism for driving the powder spreading roller to rotate around a roller shaft, and a horizontal moving mechanism for driving the powder spreading roller to horizontally move along the powder spreading direction, where the powder spreading roller can also be replaced by a powder spreading brush, and in any case, the whole powder spreading device 8 and the powder supplying cylinder 4 are not the focus of improvement of the present application and are not repeated herein.

Referring to fig. 2, in some embodiments, a lifting mechanism for driving the inner constraint 9 and the outer constraint 10 to move up and down in the forming cylinder 3 is further provided in the forming cylinder 3, after the inner constraint 9 and the outer constraint 10 are kept flush with the forming lifting platform 6 under the driving of the lifting mechanism, the lifting mechanism drives the inner constraint 9 and the outer constraint 10 to keep synchronous movement with the forming lifting platform 6, so that the forming lifting platform 6, the inner constraint 9 and the outer constraint 10 together form a large lifting platform, that is, the lifting platform can be restored to a state before improvement, thereby the additive manufacturing of large-size and solid parts can be satisfied, and the equipment universality is greatly improved. In addition, through designing the inner constraint 9 and the outer constraint 10 to be detachably connected with the lifting mechanism, the inner constraint 9 and the outer constraint 10 with different sizes can be replaced, and the printing requirements of hollow thin-wall parts 12 with different sizes can be met.

Referring to fig. 2, specifically, the lifting mechanism includes two lifting rods 13 independently connected with the inner constraint 9 and the outer constraint 10, and the same formed lifting table 6 is driven by the lifting rods 13 to realize lifting, and the power source of the lifting rods 13 can be an air cylinder, an oil cylinder, a linear motor or the like. When the hollow thin-walled member 12 is approximately cylindrical, such as an aeroengine case, the shape of the inner constraint 9 is cylindrical, the shape of the forming lifting table 6 is circular, the shape of the inner cavity of the outer constraint 10 is cylindrical, the shape is consistent with the shape and the size of the inner cavity of the forming cylinder 3, and when the size of the forming cylinder 3 is 1200mm multiplied by 600mm multiplied by 1500m, the shape and the size of the outer constraint 10 are slightly smaller than 1200mm multiplied by 600mm multiplied by 1500m so as to meet the sliding requirement.

Referring to fig. 2, in other embodiments, the apparatus further includes a ventilation system 14 for evacuating and/or filling the part forming chamber 1 with a protective gas, and the ventilation system 14 provides atmosphere protection during the additive printing process, and the specific structure of the ventilation system 14 is the prior art and will not be described herein.

Referring to fig. 2, it should be explained that, in practical application, the powder supply cylinder 4 includes a cylinder 401 and a plunger 402 disposed in the cylinder 401 to drive the powder to move up, and the powder in the cylinder 401 is driven by the plunger 402 to move up or down by a set distance. As for the materials for forming the base plate 7, the inner constraint 9 and the outer constraint 10, those skilled in the art can select the materials adaptively according to the specific printing powder, for example, stainless steel can be used.

The specific structure of the scanner 2 of the additive manufacturing apparatus is not described in detail herein, for example, when the energy beam is a laser beam or an electron beam, the scanner 2 includes a laser for providing an energy source and a three-dimensional dynamic focusing scanning galvanometer for controlling the movement of the laser, and irradiates the laser on the powder bed 5 through a protection window to melt the powder bed 5.

Application example

The GH4169 high-temperature alloy powder is used as a raw material, and the aircraft engine case structure is printed, wherein the maximum diameter of the aircraft engine case is 450mm, the height of the aircraft engine case is 420mm, the difference between the inner diameter and the outer diameter of a projection surface is 50mm, and the aircraft engine case structure is a circular ring structure with thin walls.

The concrete process for manufacturing the casing by using the additive manufacturing equipment comprises the following steps:

preparing GH4169 metal powder, and sieving to obtain powder with the granularity of 15-53 mu m; and equally dividing the powder into two powder supply cylinders;

designing a circular forming lifting table according to the size and structural characteristics of parts, wherein the outer diameter is 460mm, the inner diameter is 400mm, and the height is 450mm, simultaneously designing a cylindrical inner constraint and a cylindrical outer constraint with a cylindrical inner cavity, installing a forming substrate on the forming lifting table, installing the inner constraint and the outer constraint in a forming cylinder, and enabling the forming lifting table to smoothly slide in an annular forming cavity surrounded by the inner constraint and the outer constraint;

the powder in one cylinder is driven by a pushing plug of the first powder supply cylinder to move upwards, so that the powder in the powder supply cylinder exceeds the upper surface of the forming cavity by a certain thickness, meanwhile, the powder in the other cylinder is driven by a pushing plug of the second powder supply cylinder to move downwards by a set distance, the metal powder exceeding the upper surface of the forming cavity is firstly horizontally pushed onto a forming substrate of the forming cylinder by a powder spreading device of the first powder supply cylinder, then the residual powder is horizontally spread into a powder supply cylinder (the second powder supply cylinder) on the opposite side, and the distance of the powder moving downwards in the second powder supply cylinder is determined according to the quantity of the residual powder spread by the powder spreading device of the first powder supply cylinder so as to ensure that the upper surface of the pushed residual powder is basically flush with the upper surface of the forming cavity after the second powder supply cylinder is evenly spread by a layer;

then the energy beam selectively melts the powder on the substrate according to the planned path to process the current layer;

then the molding lifting table drives the molding substrate to descend by a layer thickness distance, the second powder supply cylinder ascends by a certain thickness distance, meanwhile, the pushing plug of the first powder supply cylinder drives powder in the cylinder to move downwards by a set distance, the powder paving device of the second powder supply cylinder paves metal powder on the processed current layer, the rest powder is paved in the first powder supply cylinder on the opposite side, the moving downwards distance of the powder in the first powder supply cylinder is determined according to the powder paving amount of the powder paving device of the second powder supply cylinder, and therefore the upper surface of the powder is basically level with the upper surface of the molding cavity after the pushed rest powder is flatly paved in the first powder supply cylinder for one layer;

the equipment is adjusted into the data printed on the lower layer to melt the powder, and the steps are repeated to realize layer-by-layer processing until the whole casing part is processed.

Any of the above-described embodiments of the present invention disclosed herein, unless otherwise stated, if they disclose a numerical range, then the disclosed numerical range is the preferred numerical range, as will be appreciated by those of skill in the art: the preferred numerical ranges are merely those of the many possible numerical values where technical effects are more pronounced or representative. Since the numerical values are more and cannot be exhausted, only a part of the numerical values are disclosed to illustrate the technical scheme of the invention, and the numerical values listed above should not limit the protection scope of the invention.

Meanwhile, if the above invention discloses or relates to parts or structural members fixedly connected with each other, the fixed connection may be understood as follows unless otherwise stated: detachably fixed connection (e.g. using bolts or screws) can also be understood as: the non-detachable fixed connection (e.g. riveting, welding), of course, the mutual fixed connection may also be replaced by an integral structure (e.g. integrally formed using a casting process) (except for obviously being unable to use an integral forming process).

In addition, terms used in any of the above-described aspects of the present disclosure to express positional relationship or shape have meanings including a state or shape similar to, similar to or approaching thereto unless otherwise stated. Any part provided by the invention can be assembled by a plurality of independent components, or can be manufactured by an integral forming process.

The above examples are only illustrative of the invention and are not intended to be limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. Nor is it necessary or impossible to exhaust all embodiments herein. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. The utility model provides a hollow thin-walled spare powder bed material increase manufacture equipment, includes part shaping room (1) and scanner (2), be equipped with shaping jar (3) and powder feed jar (4) in part shaping room (1), be equipped with shaping elevating platform (6) that are used for supporting powder bed (5) in shaping jar (3), still be equipped with in part shaping room (1) will powder in powder feed jar (4) flat-pushing arrives on shaping base plate (7) of shaping elevating platform (6) in order to form shop's powder device (8) of powder bed (5), scanner (2) are used for making this powder bed (5) be swept to the energy beam so that the powder melts, its characterized in that:

an inner constraint (9) and an outer constraint (10) are further arranged in the forming cylinder (3), a forming cavity (11) is formed between the inner constraint (9) and the outer constraint (10), the outer constraint (10) is installed in the forming cylinder (3) in a matching mode, the upper surface of the forming cavity (11) is flush with the upper surface of the forming cylinder (3), the forming lifting table (6) is installed in the forming cavity (11) in a matching sliding mode, and a tiny gap is kept between the hollow thin-wall piece (12) and the inner wall and the outer wall of the forming cavity (11) after printing and forming;

the powder feeding cylinders (4) are two in number, each powder feeding cylinder (4) is provided with one powder paving device (8), the two powder feeding cylinders (4) are oppositely arranged on two sides of the forming cylinder (3) along the powder paving direction, and the powder paving directions of the two powder paving devices (8) are opposite and are used for alternately paving powder.

2. The hollow thin-walled member powder bed additive manufacturing apparatus as set forth in claim 1, wherein: the forming cylinder is also internally provided with a lifting mechanism for driving the inner constraint (9) and the outer constraint (10) to move up and down in the forming cylinder (3), and the upper ends of the inner constraint (9) and the outer constraint (10) can be kept flush with the forming lifting table (6) under the driving of the lifting mechanism.

3. The hollow thin-walled member powder bed additive manufacturing apparatus as set forth in claim 2, wherein: the lifting mechanism comprises two lifting rods (13) which are independently connected with the inner constraint (9) and the outer constraint (10).

4. A hollow thin-walled workpiece powder bed additive manufacturing apparatus according to any of claims 1-3, wherein: the powder spreading device (8) comprises a powder spreading roller/brush and a horizontal moving mechanism for driving the powder spreading roller/brush to horizontally move along the powder spreading direction.

5. A hollow thin-walled workpiece powder bed additive manufacturing apparatus according to any of claims 1-3, wherein: the powder supply cylinder (4) comprises a cylinder body (401) and a plunger (402) which is arranged in the cylinder body (401) and drives powder to move upwards.

6. A hollow thin-walled workpiece powder bed additive manufacturing apparatus according to any of claims 1-3, wherein: also comprises a ventilation system (14) for evacuating and/or filling the part forming chamber (1) with a protective gas.

7. A hollow thin-walled workpiece powder bed additive manufacturing apparatus according to any of claims 1-3, wherein: the hollow thin-wall part (12) is an aeroengine casing.

8. A hollow thin-walled workpiece powder bed additive manufacturing apparatus according to any of claims 1-3, wherein: the energy beam is a laser beam or an electron beam.

9. A hollow thin-walled workpiece powder bed additive manufacturing apparatus according to any of claims 1-3, wherein: the forming substrate (7), the inner constraint (9) and the outer constraint (10) are made of the same material.

10. A method for additive manufacturing of a powder bed (5) of a hollow thin-walled part (12), manufactured by using the powder bed additive manufacturing equipment of the hollow thin-walled part according to any one of claims 1 to 9, characterized by comprising the following steps:

firstly, preparing metal powder, and loading the powder into a powder supply cylinder (4);

designing a forming lifting table (6) according to the size and structural characteristics of the part, installing a forming substrate (7) on the forming lifting table (6), flatly pushing metal powder onto the forming substrate (7) of a forming cylinder (3) by a powder spreading device (8), flatly spreading the rest powder into a powder supply cylinder (4) on the opposite side, and melting the powder on the substrate by an energy beam according to a planned path selected area to process a current layer; wherein a part of the powder is uniformly spread onto a forming substrate (7) of a forming cylinder (3);

thirdly, the molding lifting table (6) drives the molding substrate (7) to descend by a layer thickness distance, powder in the other powder supply cylinder (4) ascends by a certain thickness distance, the matched powder paving device (8) paves metal powder on the processed current layer, and then the rest powder is paved in the powder supply cylinder (4) at the opposite side;

and fourthly, transferring the data printed on the lower layer into the equipment to melt the powder, and processing the powder layer by layer until the whole part is processed.