Method for cleaning inner cavity of titanium alloy valve body part formed by selective laser melting based on shot impact
阅读说明：本技术 一种基于弹丸撞击的激光选区熔化成形钛合金阀体零件内腔清理方法 (Method for cleaning inner cavity of titanium alloy valve body part formed by selective laser melting based on shot impact ) 是由 于永泽 何江涛 董蓉桦 王乐 于 2020-10-30 设计创作，主要内容包括：本发明涉及一种基于弹丸撞击的激光选区熔化成形钛合金阀体零件内腔清理方法,该方法包括以下步骤：(1)对激光选区熔化成形的钛合金阀体零件进行超声波清洗；(2)使用压缩空气对阀体零件内腔进行吹干和浮粉清理；(3)将弹丸装入阀体零件内部管道,封堵流道旁通孔；(4)将阀体零件固定在振动工作台上,利用弹丸的振动撞击对阀体零件内腔进行表面清理；(5)使用高压水流对阀体零件内腔进行冲洗。本发明采用机械振动的方式,通过对内腔表面的撞击,对熔焊在阀体零件内腔表面的粉末颗粒进行清理,同时提升撞击表面的抗疲劳强度。整个过程操作简单,可以实现各种机械加工、喷砂打磨等工艺无法处理的复杂内腔表面的清理。(The invention relates to a shot impact-based method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting, which comprises the following steps: (1) carrying out ultrasonic cleaning on titanium alloy valve body parts formed by selective laser melting; (2) blowing the inner cavity of the valve body part by using compressed air and cleaning floating powder; (3) loading the shot into the pipeline inside the valve body part, and plugging the bypass hole of the flow passage; (4) fixing the valve body part on a vibration workbench, and cleaning the surface of the inner cavity of the valve body part by utilizing the vibration impact of the shot; (5) and flushing the inner cavity of the valve body part by using high-pressure water flow. The invention adopts a mechanical vibration mode, and cleans the powder particles welded on the surface of the inner cavity of the valve body part by impacting the surface of the inner cavity, and simultaneously improves the fatigue resistance of the impacting surface. The whole process is simple to operate, and the cleaning of the surfaces of the complex inner cavities which cannot be processed by various machining, sand blasting, polishing and other processes can be realized.)
1. A shot impact-based method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting is characterized by comprising the following steps:
(1) carrying out ultrasonic cleaning on titanium alloy valve body parts formed by selective laser melting;
(2) blowing the inner cavity of the valve body part by using compressed air and cleaning floating powder;
(3) loading the shot into the inner cavity of the valve body part, and plugging the bypass hole of the flow passage;
(4) fixing the valve body part on a vibration workbench, cleaning the surface of the inner cavity of the valve body part by utilizing the vibration impact of the projectile, and taking out the projectile;
(5) and flushing the inner cavity of the valve body part by using high-pressure water flow.
2. The method for cleaning the inner cavity of the titanium alloy valve body part formed by selective laser melting based on shot blasting according to claim 1, wherein the flow channel of the inner cavity of the valve body part is cylindrical, the diameter range is 5 mm-50 mm, and the wall thickness of the flow channel of the inner cavity is more than 1 mm; the valve body parts are in an annealed state.
3. The shot-impact-based method for cleaning the inner cavity of the titanium alloy valve body part formed by selective laser melting in the area, according to claim 1, is characterized in that in the step (1), industrial absolute ethyl alcohol is used as a cleaning solution, a cleaning net rack is placed at a height of 10 mm-50 mm from the bottom of a cleaning tank of ultrasonic cleaning equipment, and the cleaning solution can completely submerge the valve body part placed on the cleaning net rack; setting the ultrasonic power of the ultrasonic cleaning equipment to be 200W-600W, the ultrasonic frequency to be 20 kHz-50 kHz, and cleaning for 15 min-30 min at room temperature.
4. The method for cleaning the inner cavity of the titanium alloy valve body part formed by selective laser melting based on shot blasting according to claim 3, wherein the used cleaning net rack is formed by weaving metal wires with the diameter of 1 mm-3 mm, the minimum unit after weaving is a square grid with the side length of 30 mm-100 mm, and the material is stainless steel.
5. The shot-peening-based laser selective melting forming method for the inner cavity of the titanium alloy valve body part, as claimed in claim 1, wherein in step (2), the compressed air comprises particles, water and oil, the diameter of the particles in the compressed air is less than 0.1mm, the dew point of the water content and pressure is not higher than 3 ℃, and the concentration of the oil content is not more than 0.01mg/m3The pressure for drying the inner cavity of the valve body part is 0.6 MPa-0.9 MPa.
6. The method for cleaning the inner cavity of the titanium alloy valve body part formed by selective laser melting based on shot impact as claimed in claim 1, wherein in the step (3), according to a calculation formula of the stress when a single shot impacts the inner cavity surface of the titanium alloy valve body part in the mechanical vibration process:
in the formula: f is the impact force of the projectile acting on the surface of the inner wall; d is the diameter of the projectile; a is the vertical mechanical vibration amplitude of the vibration workbench; b is the horizontal mechanical vibration amplitude of the vibration workbench; f. of1Is the vertical vibration frequency of the vibration worktable; f. of2Is the horizontal vibration frequency of the vibration worktable; g is the acceleration of gravity;the throwing angle of the projectile is used;
stainless steel balls with the diameter of 1 mm-10 mm are selected as shot to be loaded into the inner cavity of the valve body part, the loading amount is 1/3-1/2 of the volume of the inner cavity, and all the bypass holes of the flow channel are tightly plugged by nylon plugs.
7. The shot-impact-based laser selective melting forming titanium alloy valve body part inner cavity cleaning method according to claim 1, wherein in the step (4), the vibration workbench is horizontally placed, the valve body part is fixed on the vibration workbench, and the specific steps of performing surface cleaning on the valve body part inner cavity by using the vibration impact of the shot comprise:
the method comprises the steps of fixing a valve body part on a vibration workbench by taking the material accumulation forming direction of the titanium alloy valve body part in the selective laser melting forming process to be vertical to the plane of the vibration workbench and taking the material accumulation forming direction as the upward forming direction of the valve body part as the placing direction of the valve body part, setting the vertical vibration frequency of the vibration workbench to be 20 Hz-80 Hz, the vertical amplitude range of the vibration workbench to be 0mm +/-5 mm, and the vibration duration of the vibration workbench to be 30 min-60 min, and performing vertical vibration cleaning on metal particles on the surface of an inner cavity of the valve body part;
after cleaning, taking down the valve body part and the nylon plug, pouring out the shot, and cleaning the inner cavity of the valve body part by using compressed air;
selecting a new stainless steel ball with the diameter of 1-10 mm as a bullet to be loaded into an inner cavity of a valve body part, wherein the loading amount is 1/3-1/2 of the volume of the inner cavity, and tightly plugging all flow channel bypass holes by using a nylon plug;
the method comprises the steps of taking the material accumulation forming direction of a titanium alloy valve body part in the selective laser melting forming process to be vertical to the plane of a vibration workbench, taking the forming direction to be downward as the placing direction of the valve body part, fixing the valve body part on the vibration workbench, setting the horizontal vibration frequency of the vibration workbench to be 25 Hz-60 Hz, the horizontal vibration amplitude range of the vibration workbench to be 0 mm-5 mm, and the vibration time length of the vibration workbench to be 30 min-60 min, and horizontally vibrating and polishing the surface of an inner cavity;
after cleaning, taking down the valve body part and the nylon plug, pouring out the shot, and cleaning the inner cavity of the valve body part by using compressed air;
selecting a new stainless steel ball with the diameter of 0.8-2 mm as a shot, loading the shot into an inner cavity of a valve body part, wherein the loading amount is 1/3-1/2 of the volume of the inner cavity, and tightly plugging all flow passage bypass holes by using a nylon plug;
the method comprises the steps of fixing a titanium alloy valve body part on a vibration workbench in a manner that the material accumulation forming direction of the titanium alloy valve body part in the selective laser melting forming process is perpendicular to the plane of the vibration workbench, the forming direction is upward and serves as the placing direction of the valve body part, setting the vertical vibration frequency of the vibration workbench to be 60 Hz-80 Hz, the vertical amplitude range of the vibration workbench to be 0mm +/-5 mm, the horizontal vibration frequency of the vibration workbench to be 45 Hz-60 Hz, the horizontal vibration amplitude range of the vibration workbench to be 0mm +/-5 mm, the vibration time of the vibration workbench to be 30 min-60 min, deeply cleaning gullies in an inner cavity of the valve body part and flattening the surface of the inner cavity of the valve body part.
8. The shot-impact-based method for cleaning the inner cavity of the titanium alloy valve body part formed by selective laser melting and forming in the selected area, according to claim 1, wherein in the step (5), the specific step of flushing the inner cavity of the valve body part by using high-pressure water flow comprises the following steps:
defining a bypass hole through which fluid medium enters the valve body part as a forward flushing water inlet and a bypass hole through which the fluid medium is discharged out of the valve body part as a forward flushing water outlet under the normal working state of the valve body part;
using deionized water with the pressure of 0.5MPa to 1MPa to positively flush the inner cavity of the valve body part, wherein the flushing time is 15min to 30 min;
defining a bypass hole through which fluid medium enters the valve body part as a back flushing water outlet and a bypass hole through which the fluid medium is discharged out of the valve body part as a back flushing water inlet under the normal working state of the valve body part;
and (3) reversely washing the inner cavity of the valve body part by using deionized water with the pressure of 0.5-1 MPa for 15-30 min.
9. The shot-impact-based method for cleaning the inner cavity of the titanium alloy valve body part formed by selective laser melting and forming according to claim 1, which is characterized in that: the forming method of the titanium alloy valve body part formed by selective laser melting comprises the following steps:
(1) importing the three-dimensional model of the valve body part into selective laser melting forming data preparation software, carrying out defect detection on the three-dimensional model, and repairing the detected defect to obtain a repaired three-dimensional model of the valve body part; taking the position with the minimum projection area in the repaired three-dimensional model of the valve body part as a placing position, taking the direction perpendicular to the projection plane as a forming direction, and adding process support and updating a three-dimensional data model aiming at a plane with an included angle of 135-180 degrees between the normal direction of the outer surface and the forming direction in the three-dimensional model of the valve body part to obtain the three-dimensional model of the valve body part to be layered;
(2) setting selective laser melting technological parameters, and carrying out layered slicing treatment on the three-dimensional model of the valve body part to be layered obtained in the step (1) under the control of the set selective laser melting technological parameters to obtain a layered sliced three-dimensional model of the valve body part;
(3) guiding the three-dimensional model of the valve body part subjected to layered slicing into selective laser melting forming equipment, and adopting titanium alloy powder to complete selective laser melting forming of the valve body part in a mode of spreading powder on a substrate layer by layer and melting the selective laser;
(4) and cleaning, annealing heat treatment and linear cutting are carried out on the formed valve body part to obtain the final titanium alloy valve body part.
Technical Field
The invention relates to a shot impact-based method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting, and belongs to the field of post-treatment of metal additive manufacturing.
Background
The titanium alloy valve body part containing the complex inner cavity structure needs to realize high-pressure transmission and effective regulation and control of different medium fluids in a limited space, has higher requirements on the shape and performance indexes of the inner cavity, and is a core connecting part of precision control and power units in the fields of aerospace, nuclear power military industry and the like. The existing manufacturing process of titanium alloy valve body parts mainly comprises casting, die forging, machining and welding, and due to material characteristics and process constraints, the valve body part configuration has to adopt a structural form with a simple inner cavity and a regular shape, and meanwhile, the defects of multiple processing procedures, low utilization rate of raw materials, difficulty in controlling process quality and the like exist.
With the continuous development of the Additive Manufacturing (AM) technology, the Selective Laser Melting (SLM) forming technology, which is an AM technology for selectively Melting a powder bed region based on Laser heat energy, provides a possibility for the structure and function integrated design and manufacture of valve body parts with complex inner cavity configurations, such as a curved inner flow channel. However, since the laser energy exhibits a gaussian distribution with high central energy and low edge energy, the surface of the formed part is stuck with a large amount of incompletely melted powder particles. Particularly, when the suspension structure is formed, the lower layer of the suspended part has no solid structural support, and laser directly acts on powder to form, so that a large number of incompletely melted powder particles are adhered to the upper wall of a formed inner cavity. The adhesion particles can be removed from the outer surface of the part by machining, sand blasting, grinding and the like, and an effective cleaning method for the integrally formed inner cavity structure surface is not available. The adhered powder particles are easy to fall off under the fluid flushing to form redundancy, and further the normal operation of the whole component system is influenced.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method overcomes the defects of the prior art, provides a method for cleaning the inner cavity of the titanium alloy valve body part formed by selective laser melting based on shot impact, and realizes effective cleaning of the adhered particles on the surface of the complicated inner cavity of the valve body part formed by the selective laser melting method.
In order to achieve the purpose, the invention adopts the following technical scheme: a method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting based on shot impact comprises the following steps:
(1) carrying out ultrasonic cleaning on titanium alloy valve body parts formed by selective laser melting;
(2) blowing the inner cavity of the valve body part by using compressed air and cleaning floating powder;
(3) loading the shot into the inner cavity of the valve body part, and plugging the bypass hole of the flow passage;
(4) fixing the valve body part on a vibration workbench, cleaning the surface of the inner cavity of the valve body part by utilizing the vibration impact of the projectile, and taking out the projectile;
(5) and flushing the inner cavity of the valve body part by using high-pressure water flow.
Preferably, the flow channel of the inner cavity of the valve body part is cylindrical, the diameter range is 5 mm-50 mm, and the wall thickness of the flow channel of the inner cavity is more than 1 mm; the valve body parts are in an annealed state.
Preferably, in the step (1), industrial absolute ethyl alcohol is used as a cleaning solution, the cleaning net rack is placed at a height of 10 mm-50 mm from the bottom of a cleaning tank of the ultrasonic cleaning equipment, and the valve body parts placed on the cleaning net rack can be completely submerged by the cleaning solution; setting the ultrasonic power of the ultrasonic cleaning equipment to be 200W-600W, the ultrasonic frequency to be 20 kHz-50 kHz, and cleaning for 15 min-30 min at room temperature.
Preferably, the used cleaning net rack is formed by weaving metal wires with the diameter of 1 mm-3 mm, the minimum unit after weaving is a square grid with the side length of 30 mm-100 mm, and the material is stainless steel.
Preferably, in the step (2), the compressed air comprises particles, water and oil, the diameter of the particles in the compressed air is less than 0.1mm, the dew point of the water content pressure is not higher than 3 ℃, and the concentration of the oil content is not more than 0.01mg/m3The pressure for drying the inner cavity of the valve body part is 0.6 MPa-0.9 MPa.
Preferably, in the step (3), according to a force calculation formula when a single shot impacts the surface of the inner cavity of the titanium alloy valve body part in the mechanical vibration process:
in the formula: f is the impact force of the projectile acting on the surface of the inner wall; d is the diameter of the projectile; a is the vertical mechanical vibration amplitude of the vibration workbench; b is the horizontal mechanical vibration amplitude of the vibration workbench; f. of1Is the vertical vibration frequency of the vibration worktable; f. of2Is the horizontal vibration frequency of the vibration worktable; g is the acceleration of gravity;the throwing angle of the projectile is used;
stainless steel balls with the diameter of 1 mm-10 mm are selected as shot to be loaded into the inner cavity of the valve body part, the loading amount is 1/3-1/2 of the volume of the inner cavity, and all the bypass holes of the flow channel are tightly plugged by nylon plugs.
Preferably, in step (4), the vibration table is horizontally arranged, the valve body part is fixed on the vibration table, and the specific steps of cleaning the inner cavity of the valve body part by utilizing the vibration impact of the shot comprise:
the method comprises the steps of fixing a valve body part on a vibration workbench by taking the material accumulation forming direction of the titanium alloy valve body part in the selective laser melting forming process to be vertical to the plane of the vibration workbench and taking the material accumulation forming direction as the upward forming direction of the valve body part as the placing direction of the valve body part, setting the vertical vibration frequency of the vibration workbench to be 20 Hz-80 Hz, the vertical amplitude range of the vibration workbench to be 0mm +/-5 mm, and the vibration duration of the vibration workbench to be 30 min-60 min, and performing vertical vibration cleaning on metal particles on the surface of an inner cavity of the valve body part;
after cleaning, taking down the valve body part and the nylon plug, pouring out the shot, and cleaning the inner cavity of the valve body part by using compressed air;
selecting a new stainless steel ball with the diameter of 1-10 mm as a bullet to be loaded into an inner cavity of a valve body part, wherein the loading amount is 1/3-1/2 of the volume of the inner cavity, and tightly plugging all flow channel bypass holes by using a nylon plug;
the method comprises the steps of taking the material accumulation forming direction of a titanium alloy valve body part in the selective laser melting forming process to be vertical to the plane of a vibration workbench, taking the forming direction to be downward as the placing direction of the valve body part, fixing the valve body part on the vibration workbench, setting the horizontal vibration frequency of the vibration workbench to be 25 Hz-60 Hz, the horizontal vibration amplitude range of the vibration workbench to be 0 mm-5 mm, and the vibration time length of the vibration workbench to be 30 min-60 min, and horizontally vibrating and polishing the surface of an inner cavity;
after cleaning, taking down the valve body part and the nylon plug, pouring out the shot, and cleaning the inner cavity of the valve body part by using compressed air;
selecting a new stainless steel ball with the diameter of 0.8-2 mm as a shot, loading the shot into an inner cavity of a valve body part, wherein the loading amount is 1/3-1/2 of the volume of the inner cavity, and tightly plugging all flow passage bypass holes by using a nylon plug;
the method comprises the steps of fixing a titanium alloy valve body part on a vibration workbench in a manner that the material accumulation forming direction of the titanium alloy valve body part in the selective laser melting forming process is perpendicular to the plane of the vibration workbench, the forming direction is upward and serves as the placing direction of the valve body part, setting the vertical vibration frequency of the vibration workbench to be 60 Hz-80 Hz, the vertical amplitude range of the vibration workbench to be 0mm +/-5 mm, the horizontal vibration frequency of the vibration workbench to be 45 Hz-60 Hz, the horizontal vibration amplitude range of the vibration workbench to be 0mm +/-5 mm, the vibration time of the vibration workbench to be 30 min-60 min, deeply cleaning gullies in an inner cavity of the valve body part and flattening the surface of the inner cavity of the valve body part.
Preferably, in the step (5), the specific step of flushing the inner cavity of the valve body part by using high-pressure water flow includes:
defining a bypass hole through which fluid medium enters the valve body part as a forward flushing water inlet and a bypass hole through which the fluid medium is discharged out of the valve body part as a forward flushing water outlet under the normal working state of the valve body part;
using deionized water with the pressure of 0.5MPa to 1MPa to positively flush the inner cavity of the valve body part, wherein the flushing time is 15min to 30 min;
defining a bypass hole through which fluid medium enters the valve body part as a back flushing water outlet and a bypass hole through which the fluid medium is discharged out of the valve body part as a back flushing water inlet under the normal working state of the valve body part;
and (3) reversely washing the inner cavity of the valve body part by using deionized water with the pressure of 0.5-1 MPa for 15-30 min.
Preferably, the forming method of the titanium alloy valve body part by selective laser melting forming comprises the following steps:
(1) importing the three-dimensional model of the valve body part into selective laser melting forming data preparation software, carrying out defect detection on the three-dimensional model, and repairing the detected defect to obtain a repaired three-dimensional model of the valve body part; taking the position with the minimum projection area in the repaired three-dimensional model of the valve body part as a placing position, taking the direction perpendicular to the projection plane as a forming direction, and adding process support and updating a three-dimensional data model aiming at a plane with an included angle of 135-180 degrees between the normal direction of the outer surface and the forming direction in the three-dimensional model of the valve body part to obtain the three-dimensional model of the valve body part to be layered;
(2) setting selective laser melting technological parameters, and carrying out layered slicing treatment on the three-dimensional model of the valve body part to be layered obtained in the step (1) under the control of the set selective laser melting technological parameters to obtain a layered sliced three-dimensional model of the valve body part;
(3) guiding the three-dimensional model of the valve body part subjected to layered slicing into selective laser melting forming equipment, and adopting titanium alloy powder to complete selective laser melting forming of the valve body part in a mode of spreading powder on a substrate layer by layer and melting the selective laser;
(4) and cleaning, annealing heat treatment and linear cutting are carried out on the formed valve body part to obtain the final titanium alloy valve body part.
Compared with the prior art, the invention has the following beneficial effects:
(1) the cleaning method provided by the invention has a good cleaning effect on the powder particles adhered to the surface of the inner cavity of the titanium alloy valve body part formed by selective laser melting, can effectively clean the surface of the inner cavity which cannot be treated by various machining, mechanical polishing, sand blasting and other process methods, can avoid waste liquid and pollution caused by adopting chemical and electrochemical treatment methods, and can repeatedly use the used shot and deionized water.
(2) The cleaning method provided by the invention can generate compressive stress on the surface of the inner cavity of the valve body part, has the effect of strengthening the organization and stress of the inner cavity structure, and improves the fatigue resistance of the product.
(3) The invention provides a shot-impact-based method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting, which can effectively clean adhered particles on the surface of a complex inner cavity of the valve body part formed by the selective laser melting.
Drawings
FIG. 1 is a flow chart of a cleaning method provided by the present invention.
Detailed Description
The method for cleaning the inner cavity of the titanium alloy valve body part formed by selective laser melting based on shot impact is described in detail below with reference to the accompanying drawings and the specific embodiments.
The invention relates to a shot impact-based method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting, which comprises the following steps: (1) carrying out ultrasonic cleaning on titanium alloy valve body parts formed by selective laser melting; (2) blowing the inner cavity of the valve body part by using compressed air and cleaning floating powder; (3) loading the shot into the pipeline inside the valve body part, and plugging the bypass hole of the flow passage; (4) fixing the valve body part on a vibration workbench, and cleaning the surface of the inner cavity of the valve body part by utilizing the vibration impact of the shot; (5) and flushing the inner cavity of the valve body part by using high-pressure water flow. The invention provides a method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting based on shot impact, which adopts a mechanical vibration mode to ensure that shot filled in the inner cavity of the valve body part obtains impact energy, cleans powder particles welded on the surface of the inner cavity of the valve body part by impacting the surface of the inner cavity, and simultaneously improves the fatigue resistance of the impacted surface. The whole process is simple to operate, and the cleaning of the surfaces of the complex inner cavities which cannot be processed by various machining, sand blasting, polishing and other processes can be realized.
The valve body part containing the complex multi-channel inner cavity structure needs to realize high-pressure transmission and effective regulation and control of different medium fluids in a limited space, and has higher requirements on the shape and performance indexes of the inner cavity. The traditional manufacturing process is restricted by a mould and a design, and only a structural form with a simple inner cavity and a regular shape can be formed. With the emergence and development of selective laser melting additive manufacturing technology, the possibility is provided for forming valve body parts containing any complex inner cavity structures. The preferable scheme of the selective laser melting forming valve body part comprises the following specific steps:
(1) importing the three-dimensional model of the valve body part into selective laser melting forming data preparation software, carrying out defect detection on the three-dimensional model, and repairing the detected defect to obtain a repaired three-dimensional model of the valve body part; and taking a plane which is perpendicular to the restored three-dimensional model of the valve body part and has the smallest projection area as a forming direction, adding process support and updating the three-dimensional data model aiming at a plane with an included angle of 135-180 degrees between the normal direction of the outer surface and the forming direction in the three-dimensional model of the valve body part, and obtaining the three-dimensional model of the valve body part to be layered. The method comprises the following specific steps:
establishing a three-dimensional model of the valve body part by adopting three-dimensional modeling software; after modeling is completed, the three-dimensional model is converted into a Standard Triangle Language (STL) file which can be identified by laser selection melting modeling data preparation software Magics.
The model has the problems of surface precision reduction and structural body information loss in the conversion process. Therefore, after the three-dimensional model of the valve body part is introduced into the selective laser melting forming data preparation software Magics, the model needs to be automatically detected for defects, and the specific detection contents are as follows: inverted triangular patches, bad edges and false contours, gaps, holes, interfering shells, multiple shells, overlapping and intersecting triangular patches.
And automatically repairing the detected model defects by software.
And after the repair is finished, automatically detecting and repairing the defects of the three-dimensional model of the valve body part again. Repeating the detection and repair process until the detection result shows that: the whole model has no reverse triangular surface patch, bad edge and wrong contour, gap, hole, overlapped and crossed triangular surface patch, 1 shell, no interference shell and multiple shells. At the moment, the three-dimensional model of the valve body part is repaired, and the repaired three-dimensional model of the valve body part is obtained. The probability of errors of the repaired three-dimensional model in the subsequent layering process is lower, and the printing success rate of the valve body part is improved.
The position with the minimum projection area in the valve body part three-dimensional model after restoration is the locating position, and the direction of perpendicular to projection face is the direction of formation, specifically is: setting an X-Y plane in selective laser melting data preparation software Magics as a projection plane, and adjusting the posture and the position of a three-dimensional model of the valve body part to ensure that the outer contour projection area of the valve body part on the X-Y plane is the minimum, wherein the position posture of the model is the placing direction at the moment, and the direction vertical to the projection plane is the forming direction.
Aiming at a plane with an included angle of 135-180 degrees between the normal direction of the outer surface and the forming direction in the three-dimensional model of the valve body part, adding process support and updating a three-dimensional data model, specifically comprising the following steps: after the three-dimensional model of the valve body part is determined to be placed, selecting the outer surface of a suspended model with the included angle of all normal directions and the forming direction in the model preferably being 135-180 degrees, adding a process support structure and updating the three-dimensional data model.
The added process supports are respectively cylindrical solid supports with the diameter of 1.5 mm-2.5 mm and the axial center spacing of 1 mm-3 mm, and grid supports with the spacing of 0.5 mm-1 mm, the contact part with the surface of the model is in a sawtooth shape, the tooth height is 0.3 mm-0.7 mm, the tooth top width is 0.2 mm-0.4 mm, and the tooth bottom width is 0.5 mm-0.8 mm. The supporting structure connects the suspended outer surfaces of the models into a whole along the forming direction.
(2) Setting selective laser melting technological parameters, and carrying out layered slicing treatment on the three-dimensional model of the valve body part to be layered obtained in the step (1) under the control of the set selective laser melting technological parameters to obtain a layered sliced three-dimensional model of the valve body part; the method comprises the following specific steps:
setting the melting technological parameters of the laser selective area, wherein the preferred scheme specifically comprises the following steps: the laser power is preferably 380W-420W, the scanning speed is preferably 1000 mm/s-1200 mm/s, the scanning interval is preferably 0.06 mm-0.09 mm, the scanning strategy is preferably a linear scanning mode with the interlayer rotation of 60-90 degrees, the profile scanning laser power is preferably 180W-230W, the profile scanning speed is preferably 1300 mm/s-1500 mm/s, and the layering thickness is preferably 0.04 mm-0.06 mm.
Carrying out layering slicing processing on the three-dimensional model of the valve body part to be layered obtained in the step (1), wherein the layering slicing requirements are as follows: according to the set layering thickness value, layering and slicing the three-dimensional model of the valve body part to be layered along the forming direction; and obtaining the laser scanning path and power data of the profile scanning and the entity filling of each layer according to the profile and the entity section information of each layer after slicing and the set relevant process parameters.
(3) Guiding the three-dimensional model of the valve body part subjected to layered slicing into selective laser melting forming equipment, and adopting titanium alloy powder to complete selective laser melting forming of the valve body part in a mode of spreading powder on a substrate layer by layer and melting the selective laser; the method comprises the following specific steps:
the titanium alloy powder specifically comprises: the titanium alloy powder has a particle size distribution D10 (diameter range corresponding to 10% by volume of particles in the cumulative distribution diagram) which is excellentIs selected from 15-25 mm, D50 (diameter range corresponding to 50% of particles in the cumulative distribution diagram of the powder particle size) is preferably 30-40 mm, D90 (diameter range corresponding to 90% of particles in the cumulative distribution diagram of the powder particle size) is preferably 45-55 mm, the fluidity is less than 30s/50g, and the loose packing density is preferably more than 2.2g/cm3The tap density is preferably more than 2.6g/cm3The powder shape is preferably spherical or nearly spherical and the mass fraction is not less than 97%.
The selective laser melting forming of the valve body part is completed by the mode of spreading powder and selective laser melting layer by layer on the substrate, and the selective laser melting forming method specifically comprises the following steps: guiding the three-dimensional model of the valve body part subjected to layered slicing into control software of selective laser melting forming equipment; argon with the purity of 99.999 percent is filled into the equipment; preferably, when the oxygen content in the device is stabilized below 1000ppm, a layer of flat titanium alloy powder is laid on the surface of the substrate by the metal scraper, laser scans according to the section information of the current layer, the titanium alloy powder in the scanning area is melted and solidified under the action of the laser to form a solid structure, then the substrate descends by one layer thickness, a layer of new titanium alloy powder is laid by the metal scraper, and the new titanium alloy powder is scanned again by the laser to be melted and formed, so that the reciprocating circulation is performed, and the laser selective melting and forming of the valve body part are finally completed through layer-by-layer superposition.
In the forming process, because the energy of the laser spot presents the characteristics of Gaussian distribution of high central energy and low edge energy, the metal powder cannot be completely melted due to energy attenuation at the edge of a micro molten pool formed by irradiating on the titanium alloy powder layer. The partially melted powder particles on the surface are welded with the solid structure which is cooled and solidified after being completely melted, so that a large amount of incompletely melted powder particles are adhered to the surface of the formed part. Particularly, when the suspension structure is formed, the lower layer of the suspension part is not completely supported by a solid structure, and laser directly acts on the powder layer, so that when the inner cavity flow channel structure of the valve body part is formed, a large number of incompletely melted powder particles are easily welded on the upper surface of the inner cavity flow channel.
(4) And cleaning, annealing heat treatment and linear cutting are carried out on the formed valve body part to obtain the final titanium alloy valve body part. The method comprises the following specific steps:
the formed valve body part is cleaned, annealed and subjected to linear cutting, and the method specifically comprises the following steps: repeatedly carrying out gas flushing on the surface of the valve part and the inside of the transverse hole by using compressed air with the pressure of 0.5-0.8 MPa until no floating powder exists on the surface of the part and the inside of the transverse hole; placing the valve body part and the substrate into a vacuum annealing furnace, preferably when the vacuum degree in the furnace is lower than 2 x 10-2Heating is started after Pa, the heating time is preferably 75-85 minutes, the temperature is increased to preferably 750-850 +/-10 ℃, the temperature is kept for preferably 4-6 hours, and the gas is preferably taken after the furnace is cooled to below 150 ℃; the method comprises the steps of cutting and separating a part from a substrate by adopting a slow-running wire cut electrical discharge machining with the flushing pressure of 0.6-1.0 MPa preferably, the pulse interval of 20-30 mus preferably, the pulse width of 15-25 mus preferably, the open-circuit voltage of 90-110V, the peak current of 20-30A preferably, the diameter of 0.2mm brass wire preferably, the wire running speed of 100-110 mm/s preferably, and the wire tension of 8-12N preferably, and cutting and separating the part from the substrate at a position 0-2 mm away from the upper surface of the substrate preferably to obtain the final titanium alloy valve body part.
The obtained final titanium alloy valve body part is characterized by comprising a valve body main body, an inner cavity flow channel and a flow channel bypass hole. The valve body main part is a solid frame with a vertical projection structure, preferably a regular hexagon, preferably a height of 55mm and preferably a thickness of 3 mm. The inner cavity flow channel is divided into a main flow channel and a transition flow channel. The main runner is distributed in a hexagonal shape along the surface of the inner wall of the valve body main body by the axis, the upper layer and the lower layer are distributed, the cross section of the runner is preferably 6mm, and the wall thickness of the runner is preferably 1.5 mm; the transition runner is connected with the main runner and the valve body main body, the cross section of the runner is preferably 4mm in diameter, and the wall thickness of the runner is preferably 1.5 mm. The flow channel bypass holes are divided into two types, namely, under the normal working state of the part, fluid medium enters the bypass holes of the valve body part, and the fluid medium is discharged out of the bypass holes of the valve body part. The upper layer of flow channel and the lower layer of flow channel are respectively provided with 4 inflow bypass holes which are distributed on the side wall of the valve body main body and communicated with the main flow channel through transition flow channels, the diameter of the inflow bypass holes is preferably 4mm, and the wall thickness is preferably 1.5 mm; the upper and lower layers of flow passages are respectively provided with 2 outflow bypass holes which are positioned in the center of the valve body main body, the axes of the outflow bypass holes are vertical to the axes of the inflow bypass holes and communicated with the main flow passage through transition flow passages, and the diameters of the outflow bypass holes are preferably 12mm, and the wall thicknesses of the outflow bypass holes are preferably 5 mm.
The above valve body structure is only illustrative of the spirit of the present invention, but not limited to the above structure.
The titanium alloy valve body part which is formed by adopting the selective laser melting process method and contains any complex inner cavity structure has the advantage that powder particles adhered to the surface of the inner cavity can not be cleaned in the modes of mechanical polishing, sand blasting and the like. The inner cavity surface of the valve body part can be cleaned by corrosion by adopting chemical and electrochemical methods. However, the degree of surface corrosion cannot be controlled according to the structure of the inner cavity, and local excessive corrosion and stress cracking are easily caused due to the large surface roughness and residual stress of selective laser melting; meanwhile, a large amount of chemical waste liquid is generated in the cleaning process.
The invention provides a shot impact-based method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting, which is used for cleaning powder particles adhered to the surface of the inner cavity of the titanium alloy valve body part formed by selective laser melting, wherein the diameter of a flow channel is 5-50 mm, and the wall thickness of the inner cavity flow channel is more than 1mm, in a physical impact mode. The method has the advantages that the cleaning effect is obvious, the pressure stress can be applied to the surface of the inner cavity, and the fatigue strength of the valve body part is further improved. The projectile and the deionized water for cleaning can be repeatedly used, and the whole process is environment-friendly and pollution-free.
The invention discloses a shot-impact-based method for cleaning an inner cavity of a titanium alloy valve body part formed by selective laser melting, which is implemented by the preferred scheme shown in figure 1 and comprises the following specific steps:
step one, carrying out ultrasonic cleaning on titanium alloy valve body parts formed by selective laser melting. The preferred scheme is as follows:
titanium alloy valve body part specifically is: the valve body part is integrally processed and formed by using a laser beam as a heating source and adopting a selective laser melting and forming process based on titanium alloy powder bed layer by layer melting and stacking formation, and is subjected to annealing heat treatment, linear cutting and surface sand blasting treatment.
A luminal structure defined as: the valve body part is internally provided with a complex internal flow passage structure which is distributed in a three-dimensional way and communicated with multiple flow passages, the diameter of an inner cavity flow passage is 5-50 mm, the wall thickness of the inner cavity flow passage is more than 1mm, and the internal cavity structure which cannot be cleaned and processed by machining, polishing, sand blasting and other methods.
Ultrasonic cleaning, preferably according to a cavitation threshold value calculation formula in the sound source vibration process:
in the formula: pcIs the cleaning liquid cavitation threshold; p0Is at standard atmospheric pressure; pvIs the vapor pressure of the cleaning liquid; sigma is the surface tension coefficient of the cleaning solution; r0The initial radius of the cavitation nuclei of the cleaning solution.
By utilizing the characteristic that the lower the ultrasonic frequency of the cleaning liquid is, the lower the ultrasonic cavitation threshold of the cleaning liquid is, the industrial absolute ethyl alcohol is preferably selected as the cleaning liquid, the ultrasonic cleaning frequency is preferably determined to be 20 kHz-50 kHz, the power is preferably 200W-600W, and the cleaning time is preferably 15 min-30 min.
In order to prevent the sound wave from being excessively absorbed by the bottom plate or the net rack of the cleaning tank, the stainless steel net rack of the square grid which is formed by weaving stainless steel wires with the diameter of 1 mm-3 mm and the minimum unit side length of 30 mm-100 mm after weaving is selected as the cleaning net rack for placing the valve body parts, and the cleaning net rack is placed at the height of 10 mm-50 mm away from the bottom of the cleaning tank.
When cleaning, the cleaning liquid can completely submerge the valve body parts placed on the cleaning net rack.
And secondly, blowing the inner cavity of the valve body part by using compressed air and cleaning floating powder. The preferred scheme is as follows:
the particle diameter is preferably less than 0.1mm, the dew point of water content pressure is preferably not higher than 3 deg.C, and the oil content concentration is preferably not more than 0.01mg/m3And compressed air with the pressure of 0.6-0.9 MPa is preferably used for drying and cleaning the ultrasonically cleaned valve body parts.
When cleaning, firstly, nylon plugs are used for plugging all flow passage bypass holes of the valve body parts, and then compressed air is used for drying and cleaning the surfaces of the parts; then, all nylon plugs are taken down, compressed air gun ports are aligned to bypass holes of a flow passage of the valve body part one by one, compressed air is used for drying and cleaning the flow passage of the inner cavity, and the cleaning time of each flow passage bypass hole is not less than 30 s; and finally, carrying out gas flushing on the outside of the whole valve body part.
The nylon stopper specifically is: the method is characterized in that a nylon rod is used as a raw material, according to the size of a bypass hole of a flow channel of a valve body part, the projection shape of a cross section obtained through machining is consistent with the shape of the bypass hole of the flow channel of the valve body part, the maximum size of the cross section is 3-10 mm larger than the size of the bypass hole of the flow channel, the inclination angle is 5-20 degrees, and the length is 10-20 mm.
And step three, loading the shot into the inner cavity of the valve body part, and plugging the bypass hole of the flow passage. The preferred scheme is as follows:
according to a force calculation formula when a single shot impacts the inner cavity surface of the titanium alloy valve body part in the mechanical vibration process, the following is preferred:
in the formula: f is the impact force of the projectile acting on the surface of the inner wall; d is the diameter of the projectile; a is the vertical mechanical vibration amplitude of the vibration workbench; b is the horizontal mechanical vibration amplitude of the vibration workbench; f. of1Is the vertical vibration frequency of the vibration worktable; f. of2Is the horizontal vibration frequency of the vibration worktable; g is the acceleration of gravity;the throwing angle of the projectile is shown.
Stainless steel balls with the diameter of 1 mm-10 mm are selected as pills to be loaded into the inner cavity of the valve body part, the loading amount is preferably 1/3-1/2 of the volume of the inner cavity, and all the bypass holes of the flow channel are tightly plugged by nylon plugs.
And step four, fixing the valve body part on a vibration workbench, and cleaning the surface of the inner cavity of the valve body part by utilizing the vibration impact of the shot. The preferred scheme is as follows:
the method comprises the steps of fixing a valve body part on a vibration workbench by taking the material accumulation forming direction of a titanium alloy valve body in the selective laser melting forming process to be vertical to the plane of the vibration workbench and taking the material accumulation forming direction as the upward forming direction of the valve body part as the placing direction of the valve body part, setting the vertical vibration frequency of the vibration workbench to be preferably 20 Hz-80 Hz, setting the vertical amplitude range of the vibration workbench to be preferably 0 mm- +/-5 mm, setting the vibration time of the vibration workbench to be preferably 30 min-60 min, and performing vertical vibration cleaning on metal particles welded on the surface of an inner cavity of the valve body part;
after cleaning, taking down the valve body part and the nylon plug, pouring out the shot, and cleaning the inner cavity of the valve body part by using compressed air;
selecting a new stainless steel ball with the diameter of 1-10 mm as a bullet to be loaded into an inner cavity of a valve body part, wherein the loading amount is 1/3-1/2 of the volume of the inner cavity, and tightly plugging all flow channel bypass holes by using a nylon plug;
the method comprises the steps that the material accumulation forming direction of a titanium alloy valve body in the selective laser melting forming process is perpendicular to the plane of a vibration workbench, the forming direction is downward and serves as the placing direction of valve body parts, the valve body parts are fixed on the vibration workbench, the horizontal vibration frequency of the vibration workbench is set to be 25 Hz-60 Hz preferably, the horizontal vibration amplitude range of the vibration workbench is 0 mm-5 mm preferably, the vibration time of the vibration workbench is 30 min-60 min preferably, and the inner cavity surface is subjected to horizontal vibration polishing;
after cleaning, taking down the valve body part and the nylon plug, pouring out the shot, and cleaning the inner cavity of the valve body part by using compressed air;
selecting a new stainless steel ball with the diameter of 0.8-2 mm as a bullet to be loaded into an inner cavity of a valve body part, wherein the loading amount is 1/3-1/2 of the volume of the inner cavity, and tightly plugging all flow channel bypass holes by using a nylon plug;
the method comprises the steps of fixing a valve body part on a vibration workbench by taking the material accumulation forming direction of a titanium alloy valve body in the selective laser melting forming process to be vertical to the plane of the vibration workbench and the forming direction to be upward as the placing direction of the valve body part, setting the vertical vibration frequency of the vibration workbench to be preferably 60 Hz-80 Hz, setting the vertical amplitude range of the vibration workbench to be preferably 0 mm-5 mm, setting the horizontal vibration frequency of the vibration workbench to be preferably 45 Hz-60 Hz, setting the horizontal vibration amplitude range of the vibration workbench to be preferably 0 mm-5 mm, setting the vibration time of the vibration workbench to be preferably 30 min-60 min, deeply cleaning the gully in the inner cavity of the valve body part and flattening the surface of the inner cavity of the valve body part.
The direction of the material stack formation is preferably defined as: in the process of forming the materials by stacking layer by layer, the normal direction of the layers, namely the direction of the first layer pointing to the subsequent layer.
And fifthly, flushing the inner cavity of the valve body part by using high-pressure water flow. The preferred scheme is as follows:
defining a bypass hole through which fluid medium enters the valve body part as a water inlet and a bypass hole through which the fluid medium is discharged out of the valve body part as a water outlet under the normal working state of the valve body part;
the deionized water with the pressure of 0.5 MPa-1 MPa is preferably used for positively flushing the inner cavity of the valve body part, and the flushing time is preferably 15 min-30 min;
defining a bypass hole through which fluid medium enters the valve body part as a water outlet and a bypass hole through which the fluid medium is discharged out of the valve body part as a water inlet under the normal working state of the valve body part;
and (3) reversely washing the inner cavity of the valve body part by using deionized water with the pressure of 0.5-1 MPa preferably, wherein the washing time is 15-30 min.
The invention realizes a further proposal for improving the cleaning efficiency of the inner cavity of the valve body part: let the diameter of the projectile be d and the vertical vibration frequency be f1The vertical vibration amplitude is a, when it is preferable to satisfy:
0.88＜(d3×A×103)/f1 2＜3.3
during the optimal constraint condition, the valve body part can be partially melted in the selective laser melting forming process only within 30-45 min, metal particles bonded to the surface of the inner cavity by fusion welding are basically cleaned after cooling, the roughness of the surface of the inner cavity can reach Ra 15, the cleaning effect is guaranteed, the time can be effectively shortened, and the efficiency is improved.
The invention realizes the further proposal of improving the fatigue strength of the inner cavity of the valve body part: let the vertical vibration frequency be f1And the vertical vibration amplitude is A, the vibration duration is t, and when the conditions are preferably satisfied:
0.56＜(A×t)/f1 2＜1.247
under the preferable constraint condition, the shot impacts the inner cavity of the valve body part, the surface microhardness can reach 370HV to the maximum, the maximum value of residual compressive stress introduced by the surface is about 431MPa, and the influenced depth is about 0.8mm, so that the fatigue resistance of the surface of the inner cavity of the valve body part can be further improved.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
- 上一篇：一种医用注射器针头装配设备
- 下一篇：一种高效异种材料等离子电弧熔丝沉积装置设计