Composite scraper device and method for selective laser melting defect recognition and repair

Abstract

The invention relates to a composite scraper device and method for selective laser melting defect recognition and repair, the device comprises a mounting table top, a displacement sensor and a scraper assembly, the mounting table top is provided with a mounting long hole, and the mounting table top is constructed to be capable of performing linear motion; the displacement sensor is connected to the mounting table top; the scraper assembly is movably arranged in the mounting long hole, and the scraper assembly is configured to trigger the displacement sensor through vertical movement; the scraper assembly comprises a fixing seat, a scraper seat and a composite scraper which are sequentially connected, the fixing seat abuts against the mounting table top, the composite scraper comprises a scraper frame and a tool bit connected to the bottom of the scraper frame, and the tool bit is used for powder laying and defect cutting and grinding. The composite scraper device for recognizing and repairing the selective laser melting defects integrates the defect detection function and the online repairing function, and not only can effectively recognize the defects such as protrusions, but also can eliminate and repair the defects.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a composite scraper device and method for laser selective melting defect identification and repair. Background Art

[0002] Selective laser melting (SLM) is a method for forming metal parts. This technology is based on the most basic idea of ​​rapid prototyping, that is, the "incremental" manufacturing method of layer-by-layer cladding. Parts with specific geometric shapes are directly formed according to the three-dimensional CAD model. During the forming process, the metal powder is completely melted to produce metallurgical bonding. In practical applications, the equipment stacks powder layer by layer with a fixed layer thickness through a scraper. The scraper moves horizontally at a constant speed to achieve powder spreading. In the existing technology, whether it is a single scraper unidirectional powder spreading or a double scraper unidirectional and bidirectional powder spreading, the scraper is fixed and has good rigidity. When the laser melts the powder, the metal powder will be melted by the laser and other heat sources. Tiny protrusions will appear on the surface. The superposition of protrusions will affect the depth of focus and actual power. After these protrusions solidify, they will rub against the scraper during the next powder spreading process to generate force and hard collision. In severe cases, warping will occur, directly causing surface damage. Summary of the invention

[0003] The object of the present invention is to provide a composite scraper device and method for laser selective melting defect identification and repair, which can solve the technical problem of hard collision between the scraper and the protrusion mentioned in the above background technology.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a composite scraper device for laser selective melting defect identification and repair, comprising a mounting table, a displacement sensor, and a scraper assembly, wherein the mounting table is provided with a mounting long hole, and the mounting table is constructed to be able to perform linear motion; the displacement sensor is connected to the mounting table; the scraper assembly is movably arranged in the mounting long hole, and the scraper assembly is constructed to be able to trigger the displacement sensor by vertical movement; the scraper assembly comprises a fixed seat, a scraper seat and a composite scraper connected in sequence, the fixed seat abuts against the mounting table, the composite scraper comprises a scraper frame and a cutter head connected to the bottom of the scraper frame, and the cutter head is used for powder spreading and defect cutting and grinding.

[0005] In a preferred embodiment, the blade head includes a powder spreading blade head and a cutting blade blade head connected to the side end of the powder spreading blade head, the powder spreading blade head is horizontally arranged, the cutting blade blade head is arranged at an angle to the powder spreading blade head, and the cutting blade blade head is provided with a cutting portion. The powder spreading blade head is used for spreading powder, and the cutting blade blade head is used for protrusion cutting and grinding. The cutting blade blade head arranged at an angle, on the one hand, can buffer the powder spreading blade head, so that the powder spreading blade head can smoothly contact the protrusion defect to prevent direct hard collision with the protrusion and cause damage to the profile, and on the other hand, the inclined cutting blade blade head can also be applied to higher protrusion defects, and has a wider range of applications.

[0006] In a preferred embodiment, the inclination angle of the cutting blade head relative to the powder spreading blade head does not exceed 20°. The appropriate angle setting enables the cutting blade head to be suitable for both small protrusions and high protrusions. If the angle setting is too large, it is not suitable for cutting small protrusions.

[0007] In a preferred embodiment, the cutting blade heads are arranged in two groups, connected to the two sides of the powder spreading blade head respectively, and the blade heads are arranged in the direction of horizontal movement of the composite scraper in the order of cutting blade head, powder spreading blade head, and cutting blade head. The arrangement of the cutting blade heads on both sides can alternately cut or grind the raised defects with high efficiency.

[0008] In a preferred embodiment, the fixing seat is constructed as a height adjustment component for adjusting the height of the scraper seat and the composite scraper relative to the powder bed.

[0009] In a preferred embodiment, the height adjustment assembly includes an adjustment nut abutting against the mounting table and a screw threadedly matched therewith, and the bottom end of the screw is fixedly connected to the scraper seat.

[0010] In a preferred embodiment, the height adjustment assembly further comprises a locking nut connected to the upper end of the screw rod, and the locking nut is used to ensure the stability of the relative position of the screw rod and the adjustment nut.

[0011] In a preferred embodiment, the composite scraper device further comprises an elastic component connected to the mounting table, the elastic component comprises an elastic member pressed on the top of the fixing seat and an L-shaped bracket, the L-shaped bracket is used to connect the elastic member to the mounting table. By providing the elastic component, not only the stability of the horizontal movement of the scraper component can be ensured, but also the reciprocating movement of the scraper component in the vertical direction will not be affected. At the same time, the pressing force of the elastic member can also enhance the cutting force and elastic avoidance of the cutting blade head, thereby improving the safety fault tolerance.

[0012] In a preferred embodiment, the L-shaped bracket is constructed to be height-adjustable, and the pressure of the elastic member can be adjusted by adjusting the height of the L-shaped bracket to match scraper assemblies of different hardness or specifications.

[0013] Another aspect of the present invention further provides a method for laser selective melting defect identification and repair, using the composite scraper device described in any of the above schemes, comprising the following steps:

[0014] Powder spreading: The installation table drives the scraper assembly to perform linear powder spreading movement in the horizontal direction;

[0015] Defect identification: When encountering a raised defect, lift the powder spreading knife head and push the scraper assembly to move vertically upward, so that the scraper assembly triggers the displacement sensor, and the displacement sensor sends a stop signal to stop the scraper assembly from spreading powder;

[0016] Defect elimination: the installation table and the scraper assembly perform repeated reciprocating motions based on the position of the raised defect, and the cutting blade head cuts or grinds the raised defect until the cutting blade head eliminates the defect;

[0017] Continue to spread powder: When the displacement sensor no longer feeds back a touch signal, the installation table and scraper assembly continue to move in a straight line to spread powder.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: the composite scraper device for laser selective melting defect identification and repair provided by the present invention integrates defect detection and online repair functions, and adopts a scraper assembly that can reciprocate in the vertical direction relative to the installation table and a displacement sensor to cooperate with each other, so as to effectively identify defects such as protrusions, and through the displacement sensor, a composite scraper with a cutting blade head and a horizontal reciprocating motion control form, protrusion defects can be eliminated and repaired. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the overall structure of a composite scraper device for selective laser melting defect identification and repair in an embodiment of the present invention;

[0020] Figure 2 for Figure 1 Schematic diagram of the enlarged structure at position Ⅰ;

[0021] Figure 3 It is a schematic diagram of the three-dimensional structure of a composite scraper device used for selective laser melting defect identification and repair in an embodiment of the present invention;

[0022] Figure 4 It is a schematic diagram of the structure of the installation table and the scraper assembly in the embodiment of the present invention;

[0023] Figure 5 for Figure 3 A top view of

[0024] Figure 6 for Figure 4 Cross-sectional view in the BB direction;

[0025] Figure 7 It is a schematic diagram of the structure of installing the table in an embodiment of the present invention.

[0026] The meaning of each number in the figure is:

[0027] 1. Installation table; 11. Installation long hole; 2. Scraper assembly; 21. Scraper seat; 22. Compound scraper; 221. Scraper holder; 222. Powder spreading knife head; 223. Cutting blade knife head; 224. Cutting part; 23. Fastener; 24. Fixed seat (height adjustment assembly); 241. Adjustment nut; 242. Screw; 243. Locking nut; 3. Displacement sensor; 4. Installation bracket; 5. Elastic assembly; 51. Elastic part; 52. L-shaped bracket; 521. Vertical rod; 522. Horizontal rod; 523. Adjustment stud. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0030] Embodiment 1

[0031] See also Figure 1 and Figure 3 This embodiment discloses a composite scraper device for laser selective melting defect identification and repair, which mainly includes a mounting table 1, a scraper assembly 2 connected through the mounting table 1, and a displacement sensor 3 connected to the mounting table 1, and the displacement sensor 3 is arranged above the scraper assembly 2.

[0032] In this embodiment, the mounting table 1 is horizontally arranged, the scraper assembly 2 is vertically arranged, and the scraper assembly 2 is movably arranged in the mounting table 1. Specifically, the scraper assembly 2 can reciprocate in the vertical direction relative to the mounting table 1, and when the scraper assembly 2 moves upward, it can touch the displacement sensor 3. The specific implementation process is: when the scraper assembly 2 encounters a protruding defect during the horizontal powder spreading process, the scraper assembly 2 will be lifted up by the protrusion to form a vertical upward displacement, and then touch and trigger the displacement sensor 3. The displacement sensor 3 sends a signal to control the scraper assembly 2 to stop the powder spreading movement, and perform horizontal reciprocating movement based on the position of the protruding defect in situ, and continue the powder spreading movement after eliminating the protrusion through the specific structure of the scraper assembly 2 (the specific structure will be described below).

[0033] In this embodiment, the mounting table 1 is a bearing component of the entire device, which is configured to be able to perform linear motion, thereby driving the scraper assembly 2 connected thereto to perform a linear powder scraping action in the horizontal direction. Specifically, both ends of the mounting table 1 are connected to linear guide rails (not shown in the figure) through sliders, and the slider at one end is connected to a linear drive member (not shown in the figure). In actual applications, the mounting table 1 is installed above the powder bed, and the mounting table 1 and the scraper assembly 2 are driven by the linear drive member to scrape powder at a constant speed.

[0034] like Figure 7 As shown, the mounting table 1 is provided with a long mounting hole 11 for connecting the scraper assembly 2. The mounting long hole 11 is arranged perpendicular to the horizontal travel direction of the scraper assembly 2. The scraper assembly 2 passes through the long mounting hole 11. In this embodiment, the long mounting hole 11 is constructed as a rectangular hole.

[0035] The scraper assembly 2 includes a scraper seat 21 and a composite scraper 22. The composite scraper 22 is fixedly connected to the lower end of the scraper seat 21 by a fastener 23. The fastener 23 can be a detachable connection structure such as a bolt, so as to facilitate the replacement of the composite scraper 22. The scraper seat 21 passes through the mounting long hole 11 and is clearance-matched with the mounting long hole 11, so that the scraper seat 21 can reciprocate relative to the mounting long hole 11. It should be noted that the clearance between the mounting long hole 11 and the scraper seat 21 should not be too large to avoid shaking during horizontal movement.

[0036] In order to prevent the scraper seat 21 from being separated from the mounting table 1, in this embodiment, the scraper assembly 2 further includes a fixing seat 24 for fixing the scraper seat 21, the fixing seat 24 is connected to the mounting table 1, and corresponds to the position of the mounting slot 11, the fixing seat 24 is connected to the top of the scraper seat 21, can move synchronously with the scraper seat 21, and the edge of the fixing seat 24 abuts against the top of the mounting table 1, and this structure can prevent the scraper seat 21 from falling off. In this embodiment, through the connection of the fixing seat 24, the scraper seat 21 can be prevented from being separated from the mounting table 1, and the reciprocating motion of the scraper seat 21 in the vertical direction will not be affected.

[0037] The composite scraper 22 is preferably made of non-magnetic cutting tool steel, such as Figure 2 As shown, the composite scraper 22 further includes a scraper frame 221 and a cutter head fixed to the bottom of the scraper frame 221 . In this embodiment, the cutter head includes a powder spreading cutter head 222 and a cutting blade head 223 integrally connected to the side end of the powder spreading cutter head 222 .

[0038] Specifically, the powder spreading blade head 222 is used for powder spreading and is arranged horizontally; the cutting blade head 223 at the side end is used to cut defects such as protrusions during the powder spreading process. Preferably, the cutting blade heads 223 are arranged in two groups, which are respectively connected to the two side ends of the powder spreading blade head 222. The three groups of blade heads are arranged in sequence along the horizontal direction of the composite scraper 22 as the cutting blade head 223, the powder spreading blade head 222, and the cutting blade head 223. By setting two groups of cutting blade heads 223, the protrusion defects can be alternately cut or polished, effectively improving the working efficiency.

[0039] In this embodiment, the cutting blade heads 223 on both sides are set at an angle to the powder spreading head 222, and the cutting blade heads 223 are tilted upward, and the tilt angle does not exceed 20°. If the angle is set too large, it is not suitable for cutting tiny protrusions. The cutting blade head 223 is provided with a cutting portion 224 at the position connected with the powder spreading head 222. The cutting portion 224 is constructed as a serrated structure or a sanding structure, which can cut or grind away the defective structure formed. In this embodiment, by designing the cutting blade head 223 set at an angle, on the one hand, a fault-tolerant structure is formed. Through the buffering of the cutting blade head 223, the powder spreading head 222 can smoothly contact the protruding defect to prevent direct hard collision with the protrusion and cause damage to the profile; on the other hand, the inclined cutting blade head 223 can also be applied to higher protruding defects, and has a wider range of applications.

[0040] The displacement sensor 3 is fixedly connected to the top of the mounting table 1 through the mounting bracket 4. The displacement sensor 3 is arranged at the top of the fixing seat 24 of the scraper assembly 2. When the scraper assembly 2 is raised and lifted upward, the fixing seat 24 can trigger the displacement sensor 3.

[0041] For ease of understanding, the method for using the composite scraper 22 device for selective laser melting defect identification and repair provided in this embodiment is described as follows by way of example:

[0042] Spreading powder: start the linear drive component, and the installation table 1 drives the scraper assembly 2 to perform a linear powder spreading movement in the horizontal direction;

[0043] Defect identification: When encountering defects such as protrusions, the protrusions lift up the powder spreading blade head 222 under the buffering of the front cutting blade head 223, and push the scraper assembly 2 to move vertically upward as a whole, so that the fixed seat 24 of the scraper assembly 2 triggers the displacement sensor 3, and the displacement sensor 3 sends a stop signal to stop the scraper assembly 2 from spreading the powder, and control the Z axis of the powder spreading bed to stop the subsequent feeding action;

[0044] Defect elimination: the linear drive component controls the mounting table 1 and the scraper assembly 2 to perform short-distance repeated reciprocating motions based on the position of the defect, so that the cutting blade heads 223 on both sides alternately cut or grind the raised defect until the cutting blade heads 223 eliminate the defect;

[0045] Continue to spread powder: When the displacement sensor 3 no longer feeds back a touch signal, the linear drive component drives the mounting table 1 and the scraper assembly 2 to continue the linear powder spreading movement, and the Z axis of the powder spreading bed continues the feeding action.

[0046] It can be understood that the above-mentioned action processes are all controlled by a control system. The control system may specifically include a control chip or a single-chip microcomputer that can receive the signal of the displacement sensor 3 and control the linear drive according to a predetermined program, so that the linear drive can start, stop or perform other actions according to a preset process.

[0047] Embodiment 2

[0048] The composite scraper 22 device for selective laser melting defect identification and repair provided in the second embodiment has substantially the same structure as that of the first embodiment, and therefore, for the sake of brevity, only the differences are described herein.

[0049] Combination Figure 4-Figure 6 In this embodiment, the fixing seat 24 is constructed as a height adjustment component for adjusting the height of the scraper seat 21 and the composite scraper 22 relative to the powder bed to adapt to different powder thicknesses.

[0050] Specifically, the height adjustment assembly includes an adjustment nut 241 abutting against the mounting table 1 and a screw rod 242 threadedly matched therewith. Correspondingly, the top of the scraper seat 21 is provided with a mounting groove for mounting the screw rod 242. The bottom end of the screw rod 242 extends into the mounting groove and is interference-fitted therewith. The height of the screw rod 242 and the scraper seat 21 can be adjusted by screwing the adjustment nut 241.

[0051] In this embodiment, the height adjustment components are provided in at least two groups to ensure that the heights of both ends of the scraper seat 21 are consistent.

[0052] Preferably, the height adjustment assembly further includes a locking nut 243 connected to the upper end of the screw rod 242 , and the locking nut 243 ensures the stability of the relative position of the screw rod 242 and the adjustment nut 241 .

[0053] Embodiment 3

[0054] The composite scraper 22 device for selective laser melting defect identification and repair provided in the third embodiment has substantially the same structure as that of the first embodiment, and therefore, for the sake of brevity, only the differences are described herein.

[0055] Combination Figure 1 and Figure 3 In this embodiment, the composite scraper 22 device for laser selective melting defect identification and repair also includes an elastic component 5 for pressing the scraper seat 21. The elastic component 5 can give a predetermined pressing force to the scraper seat 21 to prevent shaking during the powder spreading process. It can be understood that the elastic component 5 can apply the pressing force directly to the scraper seat 21, or to the fixed seat 24 connected to the scraper seat 21.

[0056] Specifically, the elastic component 5 includes an elastic member 51 pressed on the top of the scraper seat 21 or the fixing seat 24 and an L-shaped bracket 52, one end of the L-shaped bracket 52 is connected to the top of the elastic member 51, and the other end is connected to the mounting table 1. In this embodiment, the elastic member 51 can be an elastic structure such as a spring or a tension spring.

[0057] By providing the elastic component 5, not only the stability of the horizontal movement of the scraper component 2 can be ensured, but also the reciprocating movement of the scraper component 2 in the vertical direction will not be affected. When encountering a convex defect, the scraper component 2 can overcome the force of the elastic component 51 and move upward. At the same time, the pressing force of the elastic component 51 can also enhance the cutting force and elastic avoidance of the cutting blade head 223, thereby improving the safety fault tolerance.

[0058] To ensure the clamping effect, the elastic components 5 can be set to 2-3 groups, but it is not advisable to set too many to prevent the clamping force from being too large to hinder the scraper component 2 from moving upward.

[0059] In a preferred embodiment, the height of the L-shaped bracket 52 is adjustable, so that it can fine-tune the pressure of the elastic member 51 to match the scraper assembly 2 of different hardness or specifications. Specifically, the vertical rod 521 of the L-shaped bracket 52 can be a telescopic rod; the vertical rod 521 can also be hinged to the mounting table 1. To ensure the stability of the L-shaped bracket 52 in this state, the horizontal rod 522 of the L-shaped bracket 52 is fixedly connected with an adjustment stud 523, and the bottom end of the adjustment stud 523 is threadedly connected to the mounting table 1. Then, the adjustment stud 523 can limit the L-shaped bracket and can also make the horizontal rod 522 and the adjustment stud 523 move synchronously.

[0060] The composite scraper 22 device for laser selective melting defect identification and repair provided by the present invention integrates defect detection and online repair functions, and adopts a scraper assembly 2 that can reciprocate in the vertical direction relative to the installation table 1 and a displacement sensor 3 to cooperate with each other, so as to effectively identify defects such as protrusions. Through the displacement sensor 3, the composite scraper 22 with a cutting blade head 223 and the control form of horizontal reciprocating motion, the protrusion defects can be eliminated and repaired.

[0061] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A composite scraper device for laser selective melting defect identification and repair, characterized in that: include: A mounting table (1) provided with a mounting slot (11), wherein the mounting table (1) is configured to be capable of linear motion; A displacement sensor (3) connected to the mounting table (1); A scraper assembly (2) is movably arranged in the mounting slot (11), and the scraper assembly (2) is constructed to be able to trigger the displacement sensor (3) by vertical movement; the scraper assembly (2) comprises a fixed seat (24), a scraper seat (21) and a composite scraper (22) connected in sequence, the fixed seat (24) abuts against the mounting table (1), and the composite scraper (22) comprises a scraper frame (221) and a blade head connected to the bottom of the scraper frame (221), and the blade head is used for powder spreading and defect cutting.

2. The composite scraper device for selective laser melting defect identification and repair according to claim 1, characterized in that: The blade head comprises a powder spreading blade head (222) and a cutting blade head (223) connected to the side end of the powder spreading blade head (222); the powder spreading blade head (222) is arranged horizontally; the cutting blade head (223) is arranged at an angle to the powder spreading blade head (222); and the cutting blade head (223) is provided with a cutting portion (224).

3. The composite scraper device for selective laser melting defect identification and repair according to claim 2, characterized in that: The inclination angle of the cutting blade head (223) relative to the powder spreading blade head (222) does not exceed 20°.

4. The composite scraper device for selective laser melting defect identification and repair according to claim 2, characterized in that: The cutting blade heads (223) are arranged in two groups, which are respectively connected to the two sides of the powder spreading blade head (222). The blade heads are arranged in sequence as a cutting blade head (223), a powder spreading blade head (222), and a cutting blade head (223) along the horizontal moving direction of the composite scraper (22).

5. The composite scraper device for selective laser melting defect identification and repair according to claim 1, characterized in that: The fixing seat (24) is constructed as a height adjustment component, which is used to adjust the height of the scraper seat (21) and the composite scraper (22) relative to the powder bed.

6. The composite scraper device for selective laser melting defect identification and repair according to claim 5, characterized in that: The height adjustment assembly comprises an adjustment nut (241) abutting against the mounting table (1) and a screw rod (242) threadably matched therewith, wherein the bottom end of the screw rod (242) is fixedly connected to the scraper seat (21).

7. The composite scraper device for selective laser melting defect identification and repair according to claim 6, characterized in that: The height adjustment assembly further comprises a locking nut (243) connected to the upper end of the screw rod (242).

8. The composite scraper device for selective laser melting defect identification and repair according to claim 1, characterized in that: The composite scraper device further comprises an elastic component (5) connected to the mounting table (1), the elastic component (5) comprising an elastic member (51) pressed on the top of the fixing seat (24) or the scraper seat (21) and an L-shaped bracket (52), the L-shaped bracket (52) being used to connect the elastic member (51) to the mounting table (1).

9. The composite scraper device for selective laser melting defect identification and repair according to claim 8, characterized in that: The L-shaped bracket (52) is configured to be height-adjustable.

10. A method for defect identification and repair of laser selective melting, characterized in that: The composite scraper device according to any one of claims 1 to 9 comprises the following steps: Powder spreading: the installation table (1) drives the scraper assembly (2) to perform a linear powder spreading movement in the horizontal direction; Defect identification: When a raised defect is encountered, the powder spreading blade head (222) is lifted up, and the scraper assembly (2) is pushed to move vertically upward, so that the scraper assembly (2) triggers the displacement sensor (3), and the displacement sensor (3) sends a stop signal, so that the scraper assembly (2) stops the powder spreading action; Defect elimination: the installation table (1) and the scraper assembly (2) perform repeated reciprocating motions based on the position of the raised defect, and the cutting blade head (223) cuts or grinds the raised defect until the cutting blade head (223) eliminates the defect; Continue spreading powder: When the displacement sensor (3) no longer feeds back a touch signal, the installation table (1) and the scraper assembly (2) continue to move in a straight line to spread powder.

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