An ultrasonic vibration powder spreading device for improving the density of powder bed

Abstract

The present invention discloses an ultrasonic vibration powder spreading device for improving the density of a powder bed; it comprises a linear guide rail and a synchronous belt, and a vibration powder spreading device slidably mounted on the linear guide rail; the synchronous belt pulls the vibration powder spreading device and reciprocates along the track of the linear guide rail; the vibration powder spreading device comprises a slider, a vibration component and a powder spreading roller; one end of the powder spreading roller is connected to the vibration component, and the axis of the powder spreading roller is perpendicular to the linear guide rail; the vibration component generates mechanical vibration and transmits the mechanical vibration to the powder spreading roller; during the powder spreading process, the powder spreading roller pushes the powder to be spread on the molding plane and compacts the powder layer by vibration. This device changes the current situation in which the density of the laid powder layer in the existing powder bed additive manufacturing process is low, and there is gas in the powder bed that cannot be timely overflowed during the powder spreading process, resulting in the non-density of the formed part, and improves the density of the powder bed additive manufacturing formed part and the mechanical properties of the formed part.

Description

Technical Field

[0001] The invention relates to a powder spreading device in the field of additive manufacturing, and in particular to an ultrasonic vibration powder spreading device for improving the density of a powder bed. Background Art

[0002] Additive manufacturing is a type of rapid prototyping technology. It is a technology that uses a digital model file as the basis, uses powdered metal or plastic and other bondable materials, and constructs objects by printing layer by layer. Its workflow can be summarized as follows: First, use 3D drawing software on the computer to design the 3D model of the part, then convert it into an stl file and slice it according to a certain layer thickness to generate a cli file. The equipment processes and shapes the pre-laid metal powder according to the generated cli file. After the scan is completed, the substrate descends to a certain depth and repeats this process until the part is completed, and the preparation of the part is completed by stacking layers.

[0003] Powder bed additive manufacturing is an important type of additive manufacturing process. Its essential characteristic is the layer-by-layer powder laying and molding process based on the powder bed. The molding process is very complicated, and the lack of density of the molded parts is a key technology that needs to be solved in powder bed additive manufacturing.

[0004] The loose powder layer and the air contained in the powder material are the main reasons for the looseness of the molded parts manufactured by adhesive injection molding. The looseness of the molded parts reduces the yield and tensile strength of the parts, which in turn affects the performance of the parts. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of insufficient density of the powder bed in the existing powder bed additive manufacturing process, and to provide an ultrasonic vibration powder spreading device for improving the density of the powder bed. The ultrasonic vibration powder spreading device of the present invention overcomes the defects of the conventional technology that the formed parts are not dense due to the loose spread powder bed and the large amount of gas contained therein, and improves the density of the formed parts in the powder bed additive manufacturing process, thereby improving the mechanical properties of the formed parts.

[0006] The present invention is achieved through the following technical solutions:

[0007] An ultrasonic vibration powder spreading device for improving the density of a powder bed, comprising a linear guide rail 1 and a synchronous belt 11, and a vibration powder spreading device 2 slidably mounted on the linear guide rail 1;

[0008] The synchronous belt 11 pulls the vibrating powder spreading device 2 to reciprocate along the track of the linear guide rail 1.

[0009] The vibrating powder spreading device 2 comprises a slider 201, a vibrating member and a powder spreading roller 3;

[0010] One end of the powder spreading roller 3 is connected to the vibrating component, and the axis of the powder spreading roller 3 and the linear guide rail 1 are perpendicular to each other;

[0011] The vibration component generates mechanical vibration and transmits the mechanical vibration to the powder spreading roller 3; during the powder spreading process, the powder spreading roller 3 pushes the powder to be spread on the forming plane and compacts the powder layer by vibration.

[0012] The vibration component includes a piezoelectric element 202 and a vibration block 203;

[0013] The piezoelectric element 202 is located between the slider 201 and the vibration block 203;

[0014] One end of the powder spreading roller 3 is rotatably connected to the vibration block 203;

[0015] The periphery of the slider 201 is provided with a plurality of upright guide posts 204; the periphery of the vibration block 203 is provided with a plurality of guide slideways 205 for accommodating the guide posts 204; the guide posts 204 and the guide slideways 205 are clearance-matched;

[0016] Under the action of its own weight, the lower surface of the vibration block 203 is bonded to the upper surface of the piezoelectric element 202; when the piezoelectric element 202 works due to the application of signal voltage, the mechanical energy of the continuous deformation and ultrasonic vibration of its piezoelectric body is transmitted to the vibration block 203, and the vibration block 203 vibrates along the Z-axis direction of the guide column 204, and drives the powder spreading roller 3 to vibrate synchronously and continuously along the Z-axis direction.

[0017] One end of the powder spreading roller 3 is rotationally connected to the vibration block 203; the rotational connection means that the powder spreading roller 3 is rotationally connected to the vibration block 203 via a bearing; the bearing is placed in the bearing hole 206 of the vibration block 203, and one end of the powder spreading roller 3 is inserted into the bearing hole 206.

[0018] The vibrating block 203 has a cavity inside, and a motor for driving the powder spreading roller 3 to rotate is installed in the cavity.

[0019] The powder spreading roller 3 is directly connected to the motor through a coupling, or is connected through a belt drive.

[0020] The guide column 204 is a cylindrical structure, and the lower end thereof is connected to the slider 201 via a thread.

[0021] The piezoelectric element model is PSt150 / 25×25 / 15, the amplitude is 0.1-10 μm, the working voltage is 150 V, and the working frequency is 20-40 kHz.

[0022] Compared with the prior art, the present invention has the following advantages and effects:

[0023] The vibrating powder spreading device 2 of the present invention mainly includes a slider 201, a vibration component and a powder spreading roller 3; one end of the powder spreading roller 3 is connected to the vibration component, and the axis of the powder spreading roller 3 is perpendicular to the linear guide 1; the vibration component generates mechanical vibration and transmits the mechanical vibration to the powder spreading roller 3; during the powder spreading process, the powder spreading roller 3 pushes the powder to be spread on the molding plane and compacts the powder layer by vibration. This structure changes the current situation in which the density of the laid powder layer is low in the existing powder bed additive manufacturing process, and there is gas in the powder layer that cannot overflow in time during the powder spreading process, resulting in the subsequent molded parts being not dense, and improves the density of the powder bed additively manufactured molded parts, thereby improving the mechanical properties of the powder bed additively manufactured molded parts.

[0024] The vibration component of the present invention mainly includes a piezoelectric element 202 and a vibration block 203; the piezoelectric element 202 is located between the slider 201 and the vibration block 203; one end of the powder spreading roller 3 is rotatably connected to the vibration block 203; a plurality of upright guide posts 204 are provided on the periphery of the slider 201; a plurality of guide slideways 205 for accommodating the guide posts 204 are provided on the periphery of the vibration block 203; the guide posts 204 and the guide slideways 205 are clearance-matched; under the action of the deadweight of the vibration block 203, its lower surface is engaged with the upper surface of the piezoelectric element 202; when the piezoelectric element 202 works due to the application of a signal voltage, the mechanical energy of the continuous deformation of its piezoelectric body and the ultrasonic vibration is transmitted to the vibration block 203, the vibration block 203 vibrates along the Z-axis direction of the guide post 204, and drives the powder spreading roller 3 to vibrate synchronously and continuously along the Z-axis direction. By using a plurality of upright guide posts 204, when the powder spreading roller 3 vibrates, it only vibrates up and down along the Z-axis direction to compact the powder bed, and the vibration of the powder spreading roller 3 in other directions is limited as much as possible, so that the laid powder layer is more dense and uniform. The vibration of the powder spreading roller 3 in other directions will destroy the density, uniformity and flatness of the powder layer, and instead cause the powder layer to crack, block and form grooves, etc. This is also a technical improvement made by the present invention to overcome the technical shortcomings of the low density, uniformity and flatness of the powder layer in the prior art.

[0025] In the powder spreading process of the present invention, the powder spreading roller 3 is driven by a (speed-adjustable) motor and can rotate forward or reversely, which not only further compacts the powder layer, but also makes the powder layer more uniform, flat, and the surface more smooth and dense.

[0026] The ultrasonic vibration powder spreading device of the present invention has a simple structure and simple and easy technical means; it can be widely used in BJ, SLM, SLS equipment and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of the ultrasonic vibration powder spreading device of the present invention.

[0028] Figure 2 Schematic diagram of the slider and vibration component structure.

[0029] Figure 3 Schematic diagram of the vibration block structure.

[0030] Figure 4 This is a schematic diagram of the application of the ultrasonic vibration powder spreading device of the present invention on the laser selective melting equipment. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific embodiments.

[0032] like Figure 1-4 The present invention discloses an ultrasonic vibration powder spreading device for improving the density of a powder bed, comprising a linear guide rail 1 and a synchronous belt 11, and a vibration powder spreading device 2 slidably mounted on the linear guide rail 1; the synchronous belt 11 pulls the vibration powder spreading device 2 to reciprocate along the track of the linear guide rail 1, that is, to reciprocate on the plane formed by the forming cylinder 4 and the powder supply cylinder 5.

[0033] The vibrating powder spreading device 2 comprises a slider 201 , a vibrating component and a powder spreading roller 3 .

[0034] One end of the powder spreading roller 3 is connected to the vibration component, and the axis of the powder spreading roller 3 is perpendicular to the linear guide rail 1.

[0035] The vibration component generates mechanical vibration and transmits the mechanical vibration to the powder spreading roller 3; during the powder spreading process, the powder spreading roller 3 pushes the powder to be spread on the forming plane and compacts the powder layer (or powder bed) through vibration.

[0036] It can be known from the principle of powder dynamics that the movement of powder is related to factors such as the bulk density and acceleration of the powder. In the powder bed additive manufacturing process, the gas contained in the forming powder is converted into pores in the molded part after the powder is melted or solidified, and the rapid solidification of the moving molten pool or the rapid solidification of the powder bed causes the gas to have no time to overflow and form pores, resulting in a decrease in the density of the formed part manufactured by powder bed additive manufacturing. The present invention provides a driving force for the movement of gas by high-frequency vibration. The powder laying roller vibrates and stamps the surface of the powder bed at high frequency, providing a driving force for the gas inside the powder bed to diffuse outward. At the same time, the powder quickly fills the pores left by the overflow of the gas, increasing the density of the powder bed, thereby improving the density of the formed part manufactured by powder bed additive manufacturing.

[0037] The vibration component includes a piezoelectric element 202 and a vibration block 203;

[0038] The piezoelectric element 202 is located between the slider 201 and the vibration block 203;

[0039] One end of the powder spreading roller 3 is rotatably connected to the vibration block 203;

[0040] The periphery of the slider 201 is provided with a plurality of upright guide posts 204 ; the periphery of the vibration block 203 is provided with a plurality of guide slideways 205 for accommodating the guide posts 204 ; the guide posts 204 and the guide slideways 205 are clearance-matched.

[0041] The piezoelectric crystal of the piezoelectric element 202 is deformed and restored rapidly due to the inverse piezoelectric effect; the vibration block 203 slides up and down along the guide column 204 .

[0042] Under the action of natural gravity, the lower surface of the vibration block 203 is bonded to the upper surface of the piezoelectric element 202;

[0043] In actual applications, when the powder spreading roller 3 is working on the outward stroke of spreading powder on the current layer, the powder spreading roller 3 vibrates, and the piezoelectric element 202 works due to the application of signal voltage. The mechanical energy of the continuous deformation and ultrasonic vibration of the piezoelectric body is transmitted to the vibration block 203. The vibration block 203 vibrates along the Z-axis direction of the guide column 204, and drives the powder spreading roller 3 to vibrate synchronously and continuously along the Z-axis direction. During the return stroke, the powder spreading roller 3 stops vibrating, and by fine-tuning the height of the forming cylinder 4, the powder spreading roller 3 pushes away the uneven parts of the surface of the powder layer during the outward stroke.

[0044] The use of multiple upright guide posts 204 not only guides the vibration block 203, but also makes the powder spreading roller 3 vibrate only up and down along the Z-axis direction to compact the powder bed when vibrating, and limits the vibration of the powder spreading roller 3 in other directions as much as possible, so that the laid powder layer is more dense and uniform. The vibration of the powder spreading roller 3 in other directions will destroy the density, uniformity and flatness of the powder layer, and instead cause the powder layer to crack, block crack and form grooves. This is also the technical improvement made by the present invention to overcome the technical shortcomings of the low density, uniformity and flatness of the powder layer in the prior art.

[0045] One end of the powder spreading roller 3 is rotationally connected to the vibration block 203; the rotational connection means that the powder spreading roller 3 is rotationally connected to the vibration block 203 via a bearing; the bearing is placed in the bearing hole 206 of the vibration block 203, and one end of the powder spreading roller 3 is inserted into the bearing hole 206.

[0046] The vibrating block 203 has a cavity inside, and a motor for driving the powder spreading roller 3 is installed in the cavity. The powder spreading roller 3 is driven by the motor and can also rotate forward or reverse, which not only further compacts the powder layer, but also makes the powder layer more uniform, flat, and the surface is smoother and denser. The motor has a control module to achieve speed and forward and reverse rotation adjustment.

[0047] The powder spreading roller 3 is directly connected to the motor through a coupling, or is connected through a belt drive or the like according to specific application requirements.

[0048] The guide post 204 is a cylindrical structure, and its lower end is connected to the slider 201 through a thread. This thread structure is convenient for installation and disassembly, and the guide post 204 is more firmly fixed to the slider 201.

[0049] The piezoelectric element model is PSt150 / 25×25 / 15, the amplitude is 0.1-10μm, the working voltage is 150V, and the working frequency is 20-40kHz. By controlling the frequency, amplitude, vibration time and other parameters of the piezoelectric element, the gas contained in the forming powder can be quickly overflowed and the powder bed can be compacted. The specific parameters can be determined according to the actual application.

[0050] The slider 201 of the present invention is made of metal and has a partial hollow structure inside, which is used to reserve installation space for other components, such as a motor that drives it to rotate.

[0051] As described above, the present invention can be implemented well.

[0052] The implementation methods of the present invention are not limited to the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. An ultrasonic vibration powder spreading device for improving the density of a powder bed, comprising a linear guide rail (1) and a synchronous belt (11), and a vibration powder spreading device (2) slidably mounted on the linear guide rail (1); the synchronous belt (11) pulls the vibration powder spreading device (2) to reciprocate along the track of the linear guide rail (1); the characteristics are: The vibrating powder spreading device (2) comprises a slider (201), a vibrating component and a powder spreading roller (3); One end of the powder spreading roller (3) is connected to the vibration component, and the axis of the powder spreading roller (3) and the linear guide rail (1) are perpendicular to each other; The vibration component generates mechanical vibration and transmits the mechanical vibration to the powder spreading roller (3); during the powder spreading process, the powder spreading roller (3) pushes the powder to be spread flat on the molding plane and compacts the powder layer through vibration; The vibration component comprises a piezoelectric element (202) and a vibration block (203); The piezoelectric element (202) is located between the slider (201) and the vibration block (203); One end of the powder spreading roller (3) is rotatably connected to the vibration block (203); The periphery of the sliding block (201) is provided with a plurality of upright guide posts (204); the periphery of the vibration block (203) is provided with a plurality of guide slideways (205) for accommodating the guide posts (204); the guide posts (204) and the guide slideways (205) are clearance-matched; The lower surface of the vibration block (203) is bonded to the upper surface of the piezoelectric element (202) under the action of its own weight; when the piezoelectric element (202) is in operation due to the application of a signal voltage, the mechanical energy of the continuous deformation of its piezoelectric body and ultrasonic vibration is transmitted to the vibration block (203), the vibration block (203) vibrates along the Z-axis direction of the guide column (204), and drives the powder spreading roller (3) to vibrate synchronously and continuously along the Z-axis direction.

2. The ultrasonic vibration powder spreading device for improving the density of the powder bed according to claim 1, characterized in that: One end of the powder spreading roller (3) is rotatably connected to the vibration block (203); the rotatable connection means that the powder spreading roller (3) is rotatably connected to the vibration block (203) via a bearing; the bearing is placed in a bearing hole (206) of the vibration block (203), and one end of the powder spreading roller (3) is inserted into the bearing hole (206).

3. The ultrasonic vibration powder spreading device for improving the density of the powder bed according to claim 2, characterized in that: The vibrating block (203) has a cavity inside, and a motor for driving the powder spreading roller (3) to rotate is installed in the cavity.

4. The ultrasonic vibration powder spreading device for improving the density of the powder bed according to claim 2, characterized in that: When the powder spreading roller (3) is in the forward operation of spreading powder on the current layer, the powder spreading roller (3) vibrates, the piezoelectric element (202) works due to the application of a signal voltage, and the mechanical energy of the continuous deformation and ultrasonic vibration of the piezoelectric body is transmitted to the vibration block (203), the vibration block (203) vibrates along the Z-axis direction of the guide column (204), and drives the powder spreading roller (3) to vibrate synchronously and continuously along the Z-axis direction; and when the powder spreading roller (3) is in the return operation, the vibration of the powder spreading roller (3) stops, and by finely adjusting the height of the forming cylinder (4), the powder spreading roller (3) pushes away the uneven parts of the surface of the powder layer in the forward operation.

5. The ultrasonic vibration powder spreading device for improving the density of the powder bed according to claim 2, characterized in that: The powder spreading roller (3) is directly connected to the motor via a coupling, or is connected via a belt drive.

6. The ultrasonic vibration powder spreading device for improving the density of the powder bed according to claim 2, characterized in that: The guide column (204) is a cylindrical structure, and its lower end is connected to the slider (201) via a thread.

7. The ultrasonic vibration powder spreading device for improving the density of the powder bed according to claim 4, characterized in that: The piezoelectric element model is PSt150 / 25×25 / 15, the amplitude is 0.1-10 μm, the working voltage is 150 V, and the working frequency is 20-40 kHz.

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