A method of removing print tumors within an additive manufacturing large aspect ratio runner

Abstract

The application discloses a method for removing printing nodules in an additive manufacturing large-length-diameter ratio flow channel, and comprises the following steps: step one, selecting a steel ball: the density and hardness of the steel ball are higher than those of the additive manufacturing large-length-diameter ratio flow channel, and the diameter of the steel ball is not more than 2 / 3 of the minimum cross-sectional size of the flow channel; step two, filling the steel ball in the flow channel to be cleaned of the printing nodules, and the filling rate of the steel ball is 50%-70%; step three, after the inlet and the outlet of the flow channel are closed, the flow channel filled with the steel ball is installed on a vibrating device, under the action of the vibrating device, the steel ball in the flow channel reciprocates along the length direction of the flow channel; and step four, after a set vibration time is reached, the steel ball is taken out, X-ray detection is used to detect the removal of the printing nodules adhered to the wall surface of the flow channel, if there are still printing nodules remaining, steps two to three are repeated until all the printing nodules are completely removed; and the application can effectively remove the printing nodules in the additive manufacturing large-length-diameter ratio flow channel.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing post-processing technology, specifically relating to a method for removing printing nodules inside large aspect ratio flow channels in additive manufacturing. Background Technology

[0002] Selective Laser Melting (SLM) is a novel manufacturing process that uses a laser to selectively melt metal powder and then layer it to form parts. This technology is unaffected by the complexity of the part and offers advantages such as short manufacturing cycles and low costs. It is a primary means of achieving high-performance, lightweight manufacturing and has been widely applied in aerospace, automotive, shipbuilding, and biomedical industries. Flow channel components are widely used in missile engines. Traditionally, these components are manufactured in separate parts, involving machining and milling the flow channels and laser welding the skin. This results in long, numerous welds, poor welding reliability, and a high scrap rate. With SLM, parts can be formed as a single piece, significantly shortening the manufacturing cycle and reducing costs. As design structures are optimized and iterated, additive manufacturing has become the only way to achieve high-quality forming of some flow channel components.

[0003] However, due to the characteristics of additive manufacturing processes, printed nodules randomly appear on the surface of the formed parts. These nodules are typically spherical and no larger than 1 mm. According to the requirements for controlling excess material in parts, when these nodules cannot be removed, the parts must be scrapped. When the printed nodules are on the outer surface of the part, grinding and sandblasting are effective removal methods. However, when the printed nodules are located within flow channels with a large aspect ratio, conventional grinding and sandblasting methods have poor accessibility, drastically increasing the difficulty of removal. Currently, removal is mainly achieved by hammering or high-pressure water washing, but this solution is less than 10% effective, leading to the scrapping of some parts, slowing down delivery schedules, and causing economic losses. Therefore, there is an urgent need for a method to remove printed nodules within flow channels with a large aspect ratio in additive manufacturing. Summary of the Invention

[0004] In view of this, the present invention provides a method for removing printing lumps in additive manufacturing channels with large aspect ratios, which can effectively remove printing lumps in additive manufacturing channels with large aspect ratios.

[0005] This invention is achieved through the following technical solution:

[0006] A method for removing printing nodules in additive manufacturing channels with large aspect ratios includes the following steps:

[0007] Step 1: Select steel balls: The density and hardness of the steel balls are higher than those of the additive manufacturing large aspect ratio flow channels, and the diameter of the steel balls does not exceed 2 / 3 of the minimum cross-sectional size of the flow channel; Select two specifications of steel balls with diameters R1 and R2, and R1 < R2. The ratio of steel balls with diameter R1 to steel balls with diameter R2 is 2:1.

[0008] Step 2: Fill the flow channel with steel balls to be removed, with a filling rate of 50%-70%.

[0009] Step 3: After sealing the inlet and outlet of the flow channel, install the flow channel filled with steel balls on the vibrating equipment. Under the action of the vibrating equipment, the steel balls in the flow channel reciprocate along the length of the flow channel. The steel balls will not vibrate perpendicular to the inner wall of the flow channel.

[0010] Step four: After the set vibration time is reached, remove the steel ball and use X-ray to check the removal of the printing lumps adhering to the flow channel wall. If there are still printing lumps remaining, repeat steps two to three until all printing lumps are completely removed.

[0011] Furthermore, regarding the material GH3536 with a density of 8-9 g / cm³... 3 For flow channels with a hardness of approximately 35-45 HRC and a minimum cross-sectional size of 1.5 mm, tungsten alloy steel balls with a density of 17-20 g / cm³ are selected. 3 The hardness is approximately 60-80 HRC, and the diameter of the steel ball does not exceed 1.0 mm.

[0012] Furthermore, the diameters of the two types of steel balls are 0.5 mm and 0.8 mm, respectively.

[0013] Furthermore, in step two, lubricating oil and rust inhibitor are simultaneously added inside the flow channel.

[0014] Furthermore, the process parameters of the vibration equipment are set as follows: vibration acceleration 5g-10g, vibration time 40min-60min.

[0015] Beneficial effects:

[0016] (1) This invention provides a method for removing printed lumps in the flow channel of additive manufacturing with a large length-to-diameter ratio. The method uses tungsten steel balls (i.e., steel balls made of tungsten alloy) with higher hardness and density than the substrate material and smaller size than the flow channel diameter. The balls are impacted by acceleration to remove the printed lumps in the flow channel, which is made of GH3536 high-temperature alloy. The removal effect is verified to reach 80%. This method for removing printed lumps in the flow channel is widely used in missiles, rockets and other fields.

[0017] (2) The present invention selects two specifications of steel balls with diameters of 0.5mm and 0.8mm respectively, with a quantity ratio of 2:1 and a steel ball filling rate of 50%-70%, which can ensure the impact effect on the steel balls and improve the flowability of the steel balls in the flow channel.

[0018] (3) In this invention, a rust inhibitor is added inside the flow channel filled with steel balls. The rust inhibitor can prevent the surface of the flow channel from rusting after the steel balls are impacted. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the specific process of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] Example 1:

[0022] This embodiment provides a method for removing printed nodules inside additive manufacturing flow channels with large aspect ratios. By adding small steel balls to the flow channels, the impact force of the steel balls removes the printed nodules adhering to the inner wall of the flow channels. See attached diagram. Figure 1 The specific steps are as follows:

[0023] Step 1: Select the steel ball: The density and hardness of the steel ball should be higher than those of the matrix (i.e., the additively manufactured high aspect ratio flow channel), and the diameter of the steel ball should not exceed 2 / 3 of the minimum cross-sectional dimension of the flow channel; in this embodiment, the matrix material is GH3536 with a density of 8-9 g / cm³. 3 With a hardness of approximately 35-45 HRC and a minimum cross-sectional size of 1.5 mm, the steel ball is made of tungsten alloy with a density of 17-20 g / cm³. 3 The hardness is approximately 60-80 HRC, and the diameter of the steel ball does not exceed 1.0 mm.

[0024] To ensure the impact effect on the steel balls and the fluidity of the steel balls within the flow channel, two sizes of steel balls were selected, with diameters of R1 and R2, where R1 < R2. The ratio of steel balls with diameter R1 to those with diameter R2 was 2:1. In this embodiment, the diameters of the two sizes of steel balls were 0.5 mm and 0.8 mm, with a ratio of 2:1.

[0025] Step 2: Fill the flow channel with steel balls to be removed. To improve the flowability of the steel balls in the flow channel, the filling rate of the steel balls is 50%-70% (filling rate: the ratio of the total volume of all steel balls to the volume of the flow channel cavity); at the same time, add low-viscosity lubricating oil and rust inhibitor inside the flow channel. The rust inhibitor can prevent the surface of the flow channel from rusting after the steel balls hit.

[0026] Step 3: After sealing the inlet and outlet of the flow channel, install the flow channel filled with steel balls on the vibration equipment. The process parameters of the vibration equipment are set as follows: vibration acceleration 5g-10g, vibration time 40min-60min. Under the action of the vibration equipment, the steel balls in the flow channel reciprocate along the length of the flow channel, and the steel balls will not vibrate perpendicular to the inner wall of the flow channel.

[0027] Step four: After the set vibration time is reached, remove the steel ball and use X-ray to check the removal of the printing lumps adhering to the flow channel wall. If there are still printing lumps remaining, repeat steps two to three until all printing lumps are completely removed.

[0028] Example 2:

[0029] Based on Example 1, this embodiment provides parameter verification for a method of removing printed lumps inside large aspect ratio flow channels in additive manufacturing, as detailed below:

[0030] Step 1: Select the steel balls: The steel balls should be made of tungsten alloy, with two specifications of steel balls having diameters of 0.5mm and 0.8mm respectively, and a quantity ratio of 2:1.

[0031] Step two, strictly control the steel ball filling rate to 60%;

[0032] Step 3: Strictly control the process parameters of the vibration equipment as follows: vibration acceleration 8g, vibration time 50min;

[0033] Step four: After the experiment, the removal effect was observed using X-rays. It was found that the flow channel wall was smooth and the printed lumps were cleaned up.

[0034] Therefore, the parameters selected in this embodiment are all appropriate.

[0035] Example 3:

[0036] Based on Example 1, this embodiment provides a parameter verification of the filling rate of steel balls in a method for removing burrs printed inside additive manufacturing channels with large aspect ratios, as detailed below:

[0037] Step 1: Select the steel balls: The steel balls should be made of tungsten alloy, with two specifications of steel balls having diameters of 0.5mm and 0.8mm respectively, and a quantity ratio of 2:1.

[0038] Step two: Strictly control the filling rate of the steel balls to 90%;

[0039] Step 3: Strictly control the process parameters of the vibration equipment as follows: vibration acceleration 8g, vibration time 50min;

[0040] Step four: After the experiment, the removal effect was observed using X-rays. It was found that the size of the printed lumps in the flow channel did not change. The main reason was that the filling rate of the steel balls was too high, and the movement of the steel balls inside the flow channel was restricted, so they could not form an effective impact on the foreign matter, resulting in poor removal effect.

[0041] Therefore, the 90% filling rate of the steel balls selected in this embodiment is not appropriate.

[0042] Example 4:

[0043] Based on Example 1, this embodiment provides a parameter verification of the filling rate of steel balls in a method for removing burrs printed inside additive manufacturing channels with large aspect ratios, as detailed below:

[0044] Step 1: Select the steel balls: The steel balls should be made of tungsten alloy, with two specifications of steel balls having diameters of 0.5mm and 0.8mm respectively, and a quantity ratio of 2:1.

[0045] Step two, strictly control the steel ball filling rate to 30%;

[0046] Step 3: Strictly control the process parameters of the vibration equipment as follows: vibration acceleration 8g, vibration time 50min;

[0047] Step four: After the experiment, X-ray was used to observe the removal effect. It was found that the size of the printed lumps in the flow channel remained basically unchanged. The main reason was that the filling rate of the steel balls was too low. The steel balls moved and dispersed in the flow channel and could not form an effective impact, resulting in a poor removal effect.

[0048] Therefore, the 30% filling rate of the steel balls selected in this embodiment is not appropriate.

[0049] Example 5:

[0050] Based on Example 1, this embodiment provides a parameter verification method for selecting steel balls in a method for removing burrs printed inside additive manufacturing channels with large aspect ratios, as detailed below:

[0051] Step 1: Select the steel balls: The steel balls should be made of tungsten alloy, with two specifications of steel balls having diameters of 1.2mm and 1.0mm respectively, and a quantity ratio of 2:1.

[0052] Step two, strictly control the steel ball filling rate to 60%;

[0053] Step 3: Strictly control the process parameters of the vibration equipment as follows: vibration acceleration 8g, vibration time 50min;

[0054] Step four: During the experiment, it was found that the steel ball was difficult to add and remove. After the experiment, X-ray observation was used to observe the removal effect. It was found that the size of the printed lumps in the flow channel did not change. The main reason was that the steel ball was too large and its movement inside the flow channel was restricted, so it could not form an effective impact on the foreign matter, resulting in poor removal effect.

[0055] Therefore, the diameter of the steel ball selected in this embodiment is not suitable.

[0056] Example 6:

[0057] Based on Example 1, this embodiment provides a parameter verification method for selecting steel balls in a method for removing printed lumps inside additive manufacturing channels with large aspect ratios, as detailed below:

[0058] Step 1: Select the steel balls: The steel balls should be made of tungsten alloy, with two specifications of steel balls having diameters of 0.3mm and 0.5mm respectively, and a quantity ratio of 2:1.

[0059] Step two, strictly control the steel ball filling rate to 60%;

[0060] Step 3: Strictly control the process parameters of the vibration equipment as follows: vibration acceleration 8g, vibration time 50min;

[0061] Step four: After the experiment, X-ray was used to observe the removal effect. It was found that the size of the printed lumps in the flow channel was reduced, but there were still large volumes of residue. This was mainly because the steel ball was too small and the impact force on the printed lumps was insufficient, resulting in a poor removal effect.

[0062] Therefore, the diameter of the steel ball selected in this embodiment is not suitable.

[0063] Example 7:

[0064] Based on Example 1, this embodiment provides a verification of the process parameters of a vibration apparatus for a method of removing printed lumps inside a large aspect ratio flow channel in additive manufacturing, as detailed below:

[0065] Step 1: Select the steel balls: The steel balls should be made of tungsten alloy, with two specifications of steel balls having diameters of 0.5mm and 0.8mm respectively, and a quantity ratio of 2:1.

[0066] Step two, strictly control the steel ball filling rate to 60%;

[0067] Step 3: Strictly control the process parameters of the vibration equipment as follows: vibration acceleration 8g, vibration time 20min;

[0068] Step four: After the experiment, the removal effect was observed using X-rays. It was found that the shape of the printed lumps in the flow channel changed and the sharp edges were basically eliminated, but the body was still large. This indicates that the steel ball had a removal effect on the printed lumps under the process parameters of the vibration equipment, but the effect was not obvious due to insufficient time.

[0069] Therefore, the process parameters of the vibration equipment selected in this embodiment are not suitable.

[0070] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for removing printing lumps within a high aspect ratio flow channel in additive manufacturing, characterized in that, The specific steps are as follows: Step 1: Select the appropriate steel balls: The density and hardness of the steel balls must be higher than those of the additive manufacturing high aspect ratio flow channels, and the diameter of the steel balls should not exceed 2 / 3 of the minimum cross-sectional dimension of the flow channel; the material for the additive manufacturing high aspect ratio flow channels is GH3536 with a density of 8-9 g / cm³. 3 For flow channels with a hardness of approximately 35-45 HRC and a minimum cross-sectional size of 1.5 mm, tungsten alloy steel balls with a density of 17-20 g / cm³ are selected. 3 The hardness is approximately 60-80 HRC, and the diameter of the steel ball does not exceed 1.0 mm; select two specifications of steel balls, with diameters of R1 and R2 respectively, where R1 < R2, and the ratio of steel balls with diameter R1 to steel balls with diameter R2 is 2:1; the diameters of the two specifications of steel balls are 0.5 mm and 0.8 mm respectively. Step two: Fill the flow channel where the printed lumps need to be removed with steel balls, and the filling rate of the steel balls is 50%-70%; Step 3: After sealing the inlet and outlet of the flow channel, install the flow channel filled with steel balls on the vibrating equipment. Under the action of the vibrating equipment, the steel balls in the flow channel reciprocate along the length of the flow channel. The steel balls will not vibrate perpendicular to the inner wall of the flow channel. Step four: After the set vibration time is reached, remove the steel ball and use X-ray to check the removal of the printing lumps adhering to the flow channel wall. If there are still printing lumps remaining, repeat steps two to three until all printing lumps are completely removed.

2. The method for removing printing nodules in additive manufacturing channels with large aspect ratios as described in claim 1, characterized in that, In step two, lubricating oil and rust inhibitor are added to the inside of the flow channel.

3. The method for removing printing nodules in additive manufacturing channels with large aspect ratios as described in claim 1, characterized in that, The process parameters of the vibration equipment are set as follows: vibration acceleration 5g-10g, vibration time 40min-60min.

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