A method of grinding a titanium alloy curved surface HVOF coating and a locking arm

Abstract

The application provides a grinding method and a locking arm for a titanium alloy curved surface HVOF coating. The grinding method comprises the following steps: calculating the pre-spraying size of the curved surface on a part; using a milling machine to process the curved surface with the center of the curved surface on the part as the origin until the pre-spraying size is consistent with the calculated pre-spraying size; forming a plurality of measuring points on the curved surface and measuring the size of each measuring point; spraying the curved surface on the part until the HVOF coating thickness obtained in step one is formed; using a vertical machining center, setting the machine speed and grinding parameters; installing a grinding wheel on the milling machine, selecting the origin in step one as the reference to grind the curved surface; during the grinding process, on-line measurement is performed on each measuring point until the final size is reached and the grinding is stopped; and the processing is completed. The application can satisfy the HVOF coating grinding of complex curved surfaces of products which cannot be realized by conventional grinding machines and is suitable for the HVOF coating grinding of complex curved surfaces with different geometrical shapes.

Description

Technical Field

[0001] This invention relates to the field of landing gear parts processing technology, and in particular to a grinding method for titanium alloy curved HVOF coating and a locking arm. Background Technology

[0002] The lower landing gear lock is equipped with a locking arm, such as Figure 1 As shown, one side of the locking arm 1 has a curved surface 11 (radius R90mm) and a first hole 12 (radius φ89mm) concentric with the curved surface 11. Two sets of the first hole 12 and the curved surface 11 are provided. The other side of the locking arm 1 is provided with a second hole 13.

[0003] The locking arm 1 is made of titanium alloy and has a complex curved surface 11. The surface of the curved surface 11 is coated with an HVOF coating [High Velocity Oxy-Fuel]. After coating, it needs to be ground to achieve the designed HVOF coating thickness. If traditional grinding equipment is used, it is impossible to grind the curved surface 11. Summary of the Invention

[0004] The purpose of this invention is to provide a grinding method and locking arm for HVOF coating on curved titanium alloy surfaces, which can meet the grinding requirements of complex curved surfaces with HVOF coating that cannot be achieved by conventional grinding machines, and is applicable to grinding HVOF coating on complex curved surfaces with different geometric shapes.

[0005] The technical solution of this invention is: a grinding method for HVOF coating on curved titanium alloy surfaces, comprising the following steps:

[0006] Step 1, CNC milling:

[0007] Obtain the dimensions of the curved surface on the part after HVOF spraying and the thickness of the HVOF coating on the curved surface. Calculate the dimensions of the curved surface on the part before spraying, where the dimensions before spraying = dimensions after HVOF spraying - HVOF coating thickness. Use a milling machine to machine the curved surface with the center of the curved surface on the part as the origin until it matches the calculated dimensions before spraying.

[0008] Step 2, Measurement:

[0009] Multiple measurement points are formed on the curved surface. The size of each measurement point is measured. The measurement results are compared with the pre-spraying size calculated in step one. If they match, proceed to step three. If they do not match, repeat step one.

[0010] Step 3, HVOF spraying

[0011] Spray the curved surfaces on the parts until the HVOF coating thickness obtained in step one is achieved;

[0012] Step 4, Grinding

[0013] A vertical machining center was used, with the machine tool speed and grinding parameters set. A grinding wheel was installed on the milling machine, and the origin of step one was selected as the reference point to grind the curved surface.

[0014] Step 5, Online Grinding Measurement

[0015] During the grinding process, online measurements are taken at each measurement point formed in step four. The measured dimensions are subtracted from the dimensions before spraying in step one to calculate the HVOF coating thickness. The calculated HVOF coating thickness is then compared with the obtained HVOF coating thickness. If the two are consistent, grinding is stopped, and the processing is completed.

[0016] Preferably, in step one, the surface is first semi-finished using a wave milling cutter, leaving a certain finishing allowance during machining; then the surface is finished using a polished milling cutter, and the surface dimensions are controlled by radius compensation.

[0017] Preferably, two sets of measurement points are set in the thickness direction of the part, and each set has multiple measurement points on the arc of the curved surface; the two sets of measurement points are measured by a straight line segment, and the measurement points on the arc are measured by bisecting the angle.

[0018] Preferably, the machine tool rotation speed is greater than 15000 r / min.

[0019] Preferably, in step four, a tool holder compatible with the milling machine is selected, and a screw-weighted tool holder is used to adjust the dynamic balance to G2.5.

[0020] Preferably, the grinding parameters are as follows: for rough grinding, the grinding wheel linear speed is 16-26 m / s, the feed rate is 900-1300 mm / min, and the cutting width is 1 / 4-1 / 8 of the grinding wheel width; for fine grinding, the grinding wheel linear speed is 16-26 m / s, the feed rate is 700-1200 mm / min, and the cutting width is 1 / 6-1 / 10 of the grinding wheel width.

[0021] Preferably, in step four, grinding is performed using radius compensation, and the offset value is gradually reduced by 0.03 mm per layer until the final size is achieved.

[0022] The present invention also provides a locking arm having a curved surface, the curved surface being processed by the grinding method described above for titanium alloy curved surface HVOF coating.

[0023] Compared with related technologies, the beneficial effects of the present invention are as follows:

[0024] I. This invention rationally designs the machining and measurement process flow for complex curved surfaces of titanium alloys, such as rationally selecting milling and grinding parameters, compiling CNC programs for HVOF coating milling and grinding, and completing HVOF coating grinding according to the process arrangement; this process method can meet the HVOF coating grinding of complex curved surfaces of products that cannot be achieved by conventional grinding machines, and is applicable to HVOF coating grinding of complex curved surfaces with different geometric shapes.

[0025] II. This invention achieves grinding of complex curved surfaces HVOF coatings by rationally selecting processing equipment, designing process processing schemes, selecting grinding process parameters, and compiling CNC programs for grinding complex curved surfaces. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the lock arm after processing;

[0027] Figure 2 A schematic diagram of the HVOF coating surface;

[0028] Figure 3 This is a schematic diagram of the locking arm machining process;

[0029] Figure 4 For along Figure 3 AA section view diagram;

[0030] Figure 5 A schematic diagram showing the arrangement of measurement points on the straight segment of the lock arm;

[0031] Figure 6 This is a schematic diagram showing the arrangement of measurement points on the curved surface of the lock arm.

[0032] In the attached diagram: 1. Locking arm; 11. Curved surface; 12. First hole; 13. Second hole; 14. End face; 15. Measuring point. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" used below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0034] The grinding method for HVOF coating on curved titanium alloy surfaces provided in this embodiment includes the following steps:

[0035] S1, CNC milling:

[0036] Obtain the dimensions of the curved surface after HVOF spraying and the thickness of the HVOF coating on the curved surface (60um-100um). The above dimensions are design dimensions. Figure 1As shown. Calculate the dimensions of the curved surface on the part before spraying, where the dimensions before spraying = dimensions after HVOF spraying - HVOF coating thickness. See Table 1 for specific calculated dimensions.

[0037] Table 1 Comparison of HVOF Dimensions Before and After Coating

[0038]

[0039] Select a vertical milling machine and machine surface 11 with the center of the first hole 12 as the origin. First, use a φ50 wave milling cutter to semi-finish the surface, leaving a 0.3mm finishing allowance during machining, and compile a vertical milling program. Then, use a φ50 finish milling cutter to finish the surface, controlling the high-precision dimensions of complex surfaces (such as...) through radius compensation. Figure 3 (As shown). When machining the inner contour of a part, the tool center must be offset inward by a tool radius value; when machining the outer contour of a part, the tool center must be offset outward by a tool radius value. This function, which allows the CNC device to automatically generate the tool center trajectory in real time based on a program programmed according to the part contour and preset offset parameters, is called the tool radius compensation function.

[0040] The vertical milling process is as follows:

[0041] like Figure 3 The machining procedure for surface 11 on the left side shown:

[0042] %

[0043] N0010 G40 G17 G90 G71

[0044] N0020 G91 G28 Z0.0

[0045] N0030 T00 M06

[0046] N0040 G00 G90 X-119.2315 Y15.8846 S12000 M03

[0047] N0050 G43 Z75. H00

[0048] N0060 Z-47.

[0049] N0070 G01 Z-50. F500. M08

[0050] N0080 G41 X-122.0691 Y.853

[0051] N0090 G17 G03 X-83.0153 Y17.4303 I11.2382 J27.8155

[0052] N0100 G01 X-72.79 Y42.7389

[0053] N0110 G02 X-19.5073 Y87.8605 I69.5388 J-28.0955

[0054] N0120 X47.2665 Y76.589 I19.5073 J-87.8605

[0055] N0130 G03 X51.8597 Y73.9202 I52.5183 J85.0989

[0056] N0140 G02 X62.0567 Y64.7971 I-14.3775 J-26.3303

[0057] N0150 G01 X82.8935 Y35.0391

[0058] N0160 G03 X124.6754 Y27.6718 I24.5746 J17.2073

[0059] N0170 G40

[0060] N0180 G01 X118.5292 Y41.6798

[0061] N0190 Z-47.

[0062] N0200 G00 Z75.

[0063] N0210 M02

[0064] %

[0065] like Figure 3 The machining procedure for surface 11 on the right side shown:

[0066] %

[0067] N0010 G40 G17 G90 G71

[0068] N0020 G91 G28 Z0.0

[0069] N0030 T00 M06

[0070] N0040 G00 G90 X-118.5292 Y41.6798 S12000 M03

[0071] N0050 G43 Z75. H00

[0072] N0060 Z-47.

[0073] N0070 G01 Z-50. F500. M08

[0074] N0080 G41 X-124.6754 Y27.6718

[0075] N0090 G17 G03 X-82.8935 Y35.0391 I17.2073 J24.5746

[0076] N0100 G01 X-62.0567 Y64.7971

[0077] N0110 G02 X-51.8597 Y73.9202 I24.5746 J-17.2073

[0078] N0120 G03 X-47.2665 Y76.589 I-47.9251 J87.7678

[0079] N0130 G02 X88.8566 Y-14.3008 I47.2665 J-76.589

[0080] N0140 G03 X113.7085 Y-48.6866 I29.6189 J-4.7669

[0081] N0150 G40

[0082] N0160 G01 X119.0538 Y-34.3538

[0083] N0170 Z-47.

[0084] N0180 G00 Z75.

[0085] N0190 M02

[0086] %

[0087] S2, Measurement

[0088] like Figure 5 , Figure 6 As shown, multiple measuring points 15 are formed on the curved surface 11. Two sets of measuring points 15 are arranged in the thickness direction of the locking arm 1, and each set of measuring points 15 is within 10 mm of the adjacent end face 14. Each set of measuring points 15 has multiple measuring points 15 on the arc of the curved surface 11.

[0089] The dimensions of each curved surface were measured using a ball-end micrometer to monitor the dimensions before spraying. Measurements were taken along straight lines between two sets of measurement points, and along angle bisectors for measurement points on arcs. The dimensions of each curved surface at each measurement point are recorded in Table 2.

[0090] Table 2 Surface Milling Dimension Record Sheet

[0091]

[0092] S3, HVOF spraying

[0093] The coating is applied using a combination of the UniCoatPro supersonic thermal spraying device and the WokaStar 601 SZ HVOF Spray Gun, ensuring a final coating thickness of 60-100µm.

[0094] S4, Grinding

[0095] S4.1 Grinding Machine Selection

[0096] An electric spindle vertical machining center is selected because the grinding accuracy and surface roughness requirements are high, and the machine tool speed should be greater than 15000 r / min.

[0097] S4.2 Grinding wheel selection and dynamic balancing settings

[0098] Select an HSKA63 high-speed tool holder compatible with the machine tool. Due to the high precision requirements for workpiece surface quality, the dynamic balance of the grinding wheel must be ensured to guarantee workpiece machining accuracy and efficiency. Therefore, a screw-weighted tool holder is selected, and the dynamic balance is adjusted to G2.5. This ensures the final product meets the requirements for high dimensional accuracy and high surface roughness.

[0099] S4.3 Grinding wheel selection

[0100] Grinding wheel diameter: ∅50

[0101] Abrasive: Diamond

[0102] Adhesive: Resin

[0103] Grinding wheel hardness grades: H, L, M, N, P, or R

[0104] Grinding wheel grit size: 50#-120#

[0105] S4.4 Grinding Parameter Selection

[0106] Grinding parameters are shown in Table 3.

[0107] Table 3: Grinding parameters

[0108]

[0109] S4.5, Compile the CNC program for grinding the HVOF coating on the curved surface and implement the machining.

[0110] The machining origin is the same as during milling, with the center of the first hole 12 as the origin, and the curved surface is machined. For example... Figure 3 , Figure 4 As shown, the Z-direction straightening is the end face of the first hole 12, forming a height difference of 57.5 mm. The Y-direction straightening is the center-to-center distance between the two second holes 13, which is 320 mm. Straightening refers to aligning the origin point. If the alignment point is horizontal, the center-to-center distance between the two second holes 13 is 320 mm. If the alignment point is not horizontal, the center-to-center distance between the two second holes 13 will be greater than 320 mm.

[0111] The CNC program for grinding is the same as that for milling. It uses radius compensation R90+0.2 to gradually reduce the offset value by 0.03mm per layer until the final size is achieved.

[0112] like Figure 2 As shown in the figure, 101 is the curved surface after HVOF spraying, 102 is the curved surface after HVOF coating grinding, and 103 is the grinding wheel used for HVOF coating grinding.

[0113] S5, during the grinding process, an online measurement method more accurate than the ball-end micrometer method is used to measure the grinding dimensions (measurement point distribution is as follows). Figure 5 , Figure 6 As shown in the diagram, after each finishing grinding operation, the dimensions are measured online using a Renishaw side head, with the first hole 12 as the origin, according to the points in step two. The dimensions are measured after each finishing grinding operation and calculated together with the dimensions of the milled substrate to obtain the coating thickness. This ensures the final processed dimensions and coating thickness.

[0114] Coating thickness = Grinding dimension after spraying - Dimension after substrate milling. Then compare the calculated HVOF coating thickness with the obtained HVOF coating thickness. If they match, stop grinding; processing is complete. Record the dimensions after grinding in Table 4.

[0115] Table 4. Dimensional Measurement Record after HVOF Coating and Grinding

[0116]

[0117] like Figure 1 As shown, the present invention also provides a locking arm 1, which has a curved surface 11, and the curved surface 11 is processed by the grinding method of the above-mentioned titanium alloy curved surface HVOF coating.

[0118] This invention utilizes a vertical milling machine to rough and finish mill the substrate dimensions before HVOF coating. A ball-end micrometer is cleverly selected to measure the dimensions of each point on the machined curved surface before HVOF coating. After HVOF coating, a vertical machining center with an electric spindle and a speed greater than 15000 r / min is selected. Using diamond grinding wheels and appropriate process parameters, the HVOF coating layer is ground in layers. Measurements are taken using a Renishaw online measuring head. This method of simultaneous grinding and measurement ensures the required dimensions and accuracy after grinding, as well as the coating thickness.

[0119] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A grinding method for HVOF coating on curved titanium alloy surfaces, characterized in that, Includes the following steps: Step 1, CNC milling: Obtain the dimensions of the curved surface on the part after HVOF spraying and the thickness of the HVOF coating on the curved surface. Calculate the dimensions of the curved surface on the part before spraying, where the dimensions before spraying = dimensions after HVOF spraying - HVOF coating thickness. Use a milling machine to machine the curved surface with the center of the curved surface on the part as the origin until it matches the calculated dimensions before spraying. Step 2, Measurement: Multiple measurement points are formed on the curved surface. The size of each measurement point is measured. The measurement results are compared with the pre-spraying size calculated in step one. If they match, proceed to step three. If they do not match, repeat step one. Step 3, HVOF spraying Spray the curved surfaces on the parts until the HVOF coating thickness obtained in step one is achieved; Step 4, Grinding A vertical machining center is used, with the machine tool speed and grinding parameters set as follows: For rough grinding, the grinding wheel linear speed is 16-26 m / s, the feed rate is 900-1300 mm / min, and the cutting width is 1 / 4-1 / 8 of the grinding wheel width; for finish grinding, the grinding wheel linear speed is 16-26 m / s, the feed rate is 700-1200 mm / min, and the cutting width is 1 / 6-1 / 10 of the grinding wheel width. The grinding wheel is installed on the milling machine, and the origin from step one is selected as the reference point for grinding the curved surface. Grinding is performed using radius compensation, and the offset value is gradually reduced until the final dimensions are achieved. Step 5, Online Grinding Measurement During the grinding process, online measurements are taken at each measurement point formed in step four. The measured dimensions are subtracted from the dimensions before spraying in step one to calculate the HVOF coating thickness. The calculated HVOF coating thickness is then compared with the obtained HVOF coating thickness. If the two are consistent, grinding is stopped, and the processing is completed. Two sets of measurement points are set in the thickness direction of the part. Each set of measurement points has multiple measurement points on the arc of the curved surface. The two sets of measurement points are measured by straight line segments, and the measurement points on the arc are measured by bisecting the angle.

2. The grinding method for the HVOF coating on the curved surface of titanium alloy according to claim 1, characterized in that, In step one, the surface is first semi-finished using a wave milling cutter, leaving a certain finishing allowance during machining; then the surface is finished using a polished end mill, and the surface dimensions are controlled by radius compensation.

3. The grinding method for the HVOF coating on the curved surface of titanium alloy according to claim 1, characterized in that, The machine tool speed is greater than 15000 r / min.

4. The grinding method for the HVOF coating on the curved surface of titanium alloy according to claim 1, characterized in that, In step four, select a tool holder that is compatible with the milling machine and use a screw counterweight tool holder to adjust the dynamic balance to G2.

5.

5. The grinding method for the HVOF coating on the curved surface of titanium alloy according to claim 1, characterized in that, In step four, grinding is performed using radius compensation, and the offset value is gradually reduced by 0.03 mm per layer until the final size is achieved.

6. A locking arm having a curved surface, characterized in that, The curved surface is processed by the grinding method of the titanium alloy curved surface HVOF coating as described in any one of claims 1-5.

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