Variable cross-section external circle part turning processing inner hole external circle rotation reference structure and method

Abstract

The application discloses a variable cross-section external circle part turning inner hole external circle rotation reference structure and method, which comprises an external circle part with a variable cross-section structure, a circular process reference reserved on the variable cross-section structure of the external circle part, and the circular process reference comprises at least two circular rings arranged in sequence, a distance is kept between the adjacent circular rings, and each circular ring is divided into multiple sections by a cutting groove. When the variable cross-section external circle part is turned to form an inner hole, the circular process reference is used. The application can ensure rotation stability of the part during machining and can ensure that the inner hole of the part is not deformed after the circular process reference is removed.

Description

Technical Field

[0001] This invention relates to the machining of cylindrical parts, and in particular to an outer diameter rotation reference structure for machining the inner hole of a variable cross-section outer diameter part and a method for machining the variable cross-section outer diameter part. Background Technology

[0002] In aircraft landing gear struts, the outer cylinder is the primary load-bearing structural component, requiring extremely high precision in the machining of its inner bore. Furthermore, to reduce component weight, designers often incorporate a variable cross-section (non-circular cross-section with a gradually changing outer diameter) into the outer cylinder section, depending on the load distribution.1 Figure 1 As shown. Due to structural limitations, the outer cylinder is generally a thin-walled part. The inner bore of the outer cylinder is conventionally machined by turning and grinding. During machining, one end is held by a chuck, and the other end is supported by a center rest outside the outer cylinder to ensure smooth rotation of the part (the outer cylinder during machining). However, due to the variable cross-section structure of the outer cylinder's outer circle, the support part of the center rest also has a variable cross-section. To ensure smooth rotation of the part, a circular process datum must be designed on the outside of the outer cylinder. After the inner bore of the outer cylinder is machined, the process datum on the outside of the outer cylinder is removed.

[0003] The commonly used process standard is a circular ring B with a width of approximately 50mm to 100mm (e.g., Figure 2 As shown, the process reference is a complete circular ring (used to support the parts during machining). Since the outer cylinder is a thin-walled part, after the inner hole is machined to the final size, the process reference ring is removed by milling. Due to the influence of machining stress and internal stress, the inner hole is severely deformed, and the part is scrapped.

[0004] To ensure the machining accuracy of parts, it is necessary to study the structure of the process datum. This requires ensuring the stability of the parts during rotation and preventing the internal holes of the parts from deforming due to internal stress and machining stress after the process datum is removed. Summary of the Invention

[0005] The technical problem to be solved by this invention is that, in the case of existing external cylindrical turning reference structures for machining inner holes of variable cross-section external cylindrical parts, the inner hole is severely deformed after milling due to the influence of machining stress and internal stress. This invention provides an external cylindrical turning reference structure for machining inner holes of variable cross-section external cylindrical parts that can ensure the rotational stability of the part and also ensure that the inner hole of the part does not deform after removal, as well as a turning method for variable cross-section external cylindrical parts.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] An outer cylindrical rotary reference structure for machining inner holes of a variable cross-section outer cylindrical part includes an outer cylindrical part with a variable cross-section structure. A circular process reference is reserved on the variable cross-section structure of the outer cylindrical part. The circular process reference includes at least two rings arranged in sequence, with a distance between adjacent rings, and each ring is divided into multiple segments by a cutting groove.

[0008] Furthermore, the cutting grooves on each of the rings are arranged in an alternating manner to ensure that the outer circle of the workpiece is in contact with the center frame roller when it is at any rotation angle, thereby avoiding the impact of the transverse groove passing through the center frame roller and ensuring the machining of the inner hole of the part.

[0009] Furthermore, the width of the ring is 6mm-10mm, and the distance between adjacent rings is 8mm-12mm.

[0010] Furthermore, each of the aforementioned rings has 6-10 cutting grooves evenly distributed on it.

[0011] Based on the same inventive concept, the present invention also provides a method for turning a variable cross-section outer cylindrical part, which includes the following steps:

[0012] Step S1: Based on the material, shape, and structural characteristics of the workpiece being processed, the workpiece is clamped using zero-point positioning and special tooling to complete the rough machining of the shape, and the circular process datum is reserved on the variable cross-section outer circle.

[0013] Step S2: Using the circular process datum obtained in step S1 for positioning, complete the rough machining of the inner hole of the workpiece.

[0014] Step S3: Perform heat treatment on the workpiece;

[0015] Step S4: Using a five-axis machining center, clamp the workpiece to be machined with a tooling and machine the circular process datum again;

[0016] Step S5: Clamp one workpiece on the lathe, use a dial indicator to correct the runout of the workpiece, ensuring that the runout of the workpiece is no more than 0.03mm, and complete the finishing of the inner hole of the workpiece.

[0017] Step S6: Using a five-axis machining center, with tooling positioned and clamped, perform finishing on the workpiece and remove the reserved circular process datum.

[0018] Step S7: The fitter grinds the tool marks at the circular process reference position and polishes the surface of the workpiece;

[0019] Step S8: Workpiece is put into storage.

[0020] This invention establishes a circular process reference by pre-reserving at least two rings with a width of 6mm-10mm (with an interval of 8mm-12mm between the rings) on the outer circle of the variable cross-section of the workpiece before heat treatment. This ensures the rotational stability of the workpiece during processing. At the same time, the two rings are cut off by 6-10 cutting grooves parallel to the ring axis, releasing the effects of processing stress and internal stress. After the circular process reference is removed, the inner hole of the part is guaranteed not to deform.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. The circular process reference structure of the present invention is simple, can effectively support the rotation of the outer circle on the central frame, and has a small allowance to be removed.

[0023] 2. The present invention effectively releases the internal stress after the ring is cut by cutting groove, and avoids the deformation of the inner hole of the part after the circular process reference is removed.

[0024] 3. The cutting grooves on the circular process reference ring of the present invention are arranged in a staggered pattern, which can effectively contact the center frame when the workpiece is at any rotation angle, thus avoiding the impact when the cutting grooves pass through the center frame.

[0025] 4. Experimental verification shows that when machining the inner hole of a part using a traditional cylindrical process datum with a width of approximately 50mm to 100mm, the inner hole diameter deforms by 0.27mm after machining, rendering the product unusable. However, when machining the workpiece using the segmented circular process datum designed in this invention, and then removing the circular process datum by reciprocating milling, after measuring the inner hole at 6 points across three segments, the inner hole diameter deformation is only 0.01-0.03mm. Considering measurement errors, this meets the machining requirements (experimental results are as follows). Figure 5 (As shown). Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The diagram shows the structure of the outer cylinder of the aircraft landing gear buffer strut, where (a) is a structural diagram of the outer cylinder including the variable cross-section section 1, (b) is a partial enlarged view of the variable cross-section section, and (c) is a cross-sectional view of (b) along line A-A.

[0028] Figure 2 This is a schematic diagram of the circular process reference used in conventional processes.

[0029] Figure 3 The diagram shows the structure of the circular process reference on the outer cylinder of the aircraft landing gear buffer strut of the present invention, wherein (a) is the overall structure diagram and (b) is a partial enlarged view of point 2 in (a).

[0030] Figure 4 This is a three-dimensional structural diagram of the circular process reference of the present invention.

[0031] Figure 5 The diagram shows the measurement results of the inner hole after the workpiece is machined. (a) is a schematic diagram of the milling method when removing the circular process datum, (b) is a schematic diagram of the selected position when measuring the inner hole, (c) is a cross-sectional view at A-A, (d) is a cross-sectional view at B-B and a schematic diagram of the diameter measurement points selected on the same circumference, (e) is a cross-sectional view at C-C, and (f) is the actual measurement data of each selected point. Detailed Implementation

[0032] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0033] For ease of description, the relative positions of the components, such as top, bottom, left, right, etc., are described according to the layout direction of the accompanying drawings and do not limit the structure of this patent.

[0034] Please see Figure 3 , Figure 4 An embodiment of the outer cylindrical turning reference structure for machining inner holes of variable cross-section outer cylindrical parts according to the present invention includes an outer cylindrical part 3 with a variable cross-section structure 2, wherein a circular process reference 4 is reserved on the variable cross-section structure 2 of the outer cylindrical part 3. The circular process reference 4 includes at least two sequentially arranged rings 41, with a distance between adjacent rings 41, and each ring 41 is evenly distributed with 6-10 cutting grooves 42, so that each ring 41 is divided into multiple segments by multiple cutting grooves 42. The width of the rings 41 is 6mm-10mm, and the distance between adjacent rings 41 is 8mm-12mm.

[0035] The cutting grooves 42 on each of the rings 41 are staggered to ensure that the outer circle of the workpiece is in contact with the center frame roller when it is at any rotation angle, thus avoiding the impact of the cutting grooves 42 when passing the center frame roller and ensuring the processing of the inner hole of the part.

[0036] The method for machining variable cross-section outer cylindrical parts using the circular process reference 4 of the present invention includes the following steps:

[0037] Step S1: Based on considerations of the material, shape, and structural characteristics of the workpiece being processed, the process design generally uses zero-point positioning + special tooling to clamp the workpiece, complete the rough machining of the shape, and leave a circular process datum on the variable cross-section outer circle.

[0038] Step S2: Using the machined circular process datum for positioning, complete the rough machining of the inner hole;

[0039] Step S3: Perform heat treatment on the workpiece;

[0040] Step S4: Use a five-axis machining center to machine the workpiece, clamp the workpiece in the tooling, and then machine the circular process datum.

[0041] Step S5: Clamp one piece on the lathe, use a dial indicator to correct the runout of the workpiece, ensuring that the runout of the workpiece is no more than 0.03mm, and finish machine the inner hole of the part (turning / grinding);

[0042] Step S6: Use a five-axis machining center to machine the workpiece. Position and clamp the workpiece in the tooling, perform finishing on the workpiece and remove the circular process datum reserved on the outer circle.

[0043] Step S7: The fitter grinds the tool marks at the circular process reference position and polishes the surface of the workpiece;

[0044] Step S7: Table processing / Workpiece entry.

[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A rotary reference structure for machining inner holes of a variable cross-section outer cylindrical part, comprising an outer cylindrical part with a variable cross-section structure, wherein a circular process reference is reserved on the variable cross-section structure of the outer cylindrical part, characterized in that: The circular process reference includes at least two sequentially arranged rings, with a distance between adjacent rings, and each ring is divided into multiple segments by a cutting groove.

2. The outer diameter rotation reference structure for turning inner holes of variable cross-section outer diameter parts according to claim 1, characterized in that, The cutting grooves on each of the rings are arranged in an alternating pattern.

3. The outer diameter rotation reference structure for turning inner holes of variable cross-section outer diameter parts according to claim 1, characterized in that, The width of the ring is 6mm-10mm, and the distance between adjacent rings is 8mm-12mm.

4. The outer diameter rotation reference structure for turning inner holes of variable cross-section outer diameter parts according to claim 1, characterized in that, Each of the aforementioned rings has 6-10 cutting grooves evenly distributed on it.

5. A method for turning a variable cross-section outer cylindrical part, characterized in that... Includes the following steps: Step S1: Based on the material, shape, and structural characteristics of the workpiece being processed, the workpiece is clamped using zero-point positioning and special tooling to complete the rough machining of the shape, and a circular process datum as described in any one of claims 1-4 is reserved on the variable cross-section outer circle. Step S2: Using the circular process datum obtained in step S1 for positioning, complete the rough machining of the inner hole of the workpiece. Step S3: Perform heat treatment on the workpiece; Step S4: Using a five-axis machining center, clamp the workpiece to be machined with a tooling and machine the circular process datum again; Step S5: Clamp one workpiece on the lathe, use a dial indicator to correct the runout of the workpiece, ensuring that the runout of the workpiece is no more than 0.03mm, and complete the finishing of the inner hole of the workpiece. Step S6: Using a five-axis machining center, with tooling positioned and clamped, perform finishing on the workpiece and remove the reserved circular process datum. Step S7: The fitter grinds the tool marks at the circular process reference position and polishes the surface of the workpiece; Step S8: Workpiece is put into storage.

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