Machining method and clamp for thin-wall bushing part

Abstract

The invention discloses a thin-wall bushing part machining method and a clamp, the clamp comprises an upper pressing clamping plate and a lower pressing clamping plate, the upper pressing clamping plate comprises a first cylindrical surface, and the first cylindrical surface is half of a complete cylindrical surface; the lower pressing clamping plate comprises a positioning protrusion and a second cylindrical face, the positioning protrusion is cylindrical and located at one end of the second cylindrical face, the second cylindrical face is half of the complete cylindrical face, and the second cylindrical face of the lower pressing clamping plate and the first cylindrical face of the upper pressing clamping plate are oppositely spliced to form a complete cylindrical inner hole. The axis of the cylindrical inner hole is perpendicular to the axis of the positioning protrusion. During machining, a radial sphere hole is machined firstly, then the lower pressing clamping plate positioning protrusion is used for positioning, the upper pressing clamping plate and the lower pressing clamping plate are attached to the outer surface of a part, and external threads, a counter bore and an end face are machined after one-time clamping. The problems of clamping deformation and axial positioning machining of the thin-wall bushing type parts are solved.

Description

Technical Field

[0001] The invention belongs to the field of machining of aircraft engine parts, and in particular relates to a fixture design and a machining method for machining thin-walled and deep-inner-hole parts. Background Art

[0002] In the engine structure, the material used for thin-walled liner parts is a difficult-to-process GH99 high-temperature alloy material. Figure 1 Take the bushing shown as an example: the size requirement of the inner hole of the part is φA, the depth is B, the wall thickness is only about 1mm, and the size of the radial spherical hole at one end of the part to the bottom of the part is H.

[0003] Due to the structural characteristics of the part and the difficult processing characteristics of the material, the difficulty in processing the part is mainly due to the special structure, size and technical requirements of the thin-walled liner part. One end of the part is a thin-walled cylinder, and the other end has a radial spherical hole (the radial here refers to the radial direction of the thin-walled liner part, that is, perpendicular to the axial direction of the thin-walled liner part), and the thin-walled end is a countersunk hole with a depth of B, which requires high precision. The outer circle of the countersunk hole has a connecting thread, and the thread and end face have high technical requirements for the deep inner hole. For details of the structural dimensions of the part, see Figure 1 .

[0004] During the processing of the part, whether it is part clamping or part processing, large deformation will occur, and the size and technical conditions of the part are not easy to guarantee. To ensure the precise size and technical conditions of the part, one-time clamping processing on the CNC lathe can guarantee the precision requirements of the part, but the clamping of the CNC lathe is a hydraulic clamping structure with a large clamping force. The clamping deformation of the part and the positioning of the radial hole have always been the difficult problems that plague part processing. Summary of the invention

[0005] The present invention aims to provide a processing method and fixture for thin-walled liner parts, so as to solve the problems of deformation and axial positioning processing of thin-walled liner parts during clamping, improve the processing rigidity of thin-walled liner parts, prevent deformation of thin-walled liner parts, and at the same time, use the radial spherical holes on the thin-walled liner parts to limit the axial position of the parts, realize one-time clamping processing of deep and long countersunk holes, external threads and end faces, ensure that the parts meet the requirements of technical conditions and are suitable for batch processing.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A processing fixture for thin-walled liner parts, comprising:

[0008] An upper clamping plate, wherein the upper clamping plate comprises a first cylindrical surface, and the first cylindrical surface is half of a complete cylindrical surface;

[0009] The lower clamping card plate includes a positioning protrusion and a second cylindrical surface. The positioning protrusion is cylindrical and is located at one end of the second cylindrical surface. The second cylindrical surface is half of the complete cylindrical surface. The second cylindrical surface of the lower clamping card plate and the first cylindrical surface of the upper clamping card plate are spliced ​​facing each other to form a complete cylindrical inner hole. The axis of the cylindrical inner hole is perpendicular to the axis of the positioning protrusion.

[0010] further,

[0011] The outer surface of one end of the upper clamping clamp is also provided with an annular edge coaxial with the first cylindrical surface;

[0012] The outer surface of one end of the lower clamping plate away from the positioning protrusion is also provided with an annular edge coaxial with the second cylindrical surface.

[0013] A method for processing thin-walled liner parts, comprising the following steps:

[0014] Step 1: Using a bar as a blank, clamping the left end of the bar in the axial direction, turning the outer cylindrical surface of the bar to obtain two sections of outer cylindrical surfaces with different diameters, wherein the outer cylindrical surface with a larger diameter is used as a surface for external thread processing on thin-walled liner parts, and the outer cylindrical surface with a smaller diameter is used as a positioning surface for countersink processing on thin-walled liner parts;

[0015] Step 2: Clamp the right end of the bar in the axial direction and mill the left end of the bar in the axial direction to obtain a radial spherical hole on a thin-walled liner-like part;

[0016] Step 3, using the aforementioned processing fixture, wherein the first cylindrical surface of the upper clamping card plate is fitted on the positioning surface in step 1, and the positioning protrusion of the lower clamping card plate is inserted into the radial spherical hole in step 2, while ensuring that the second cylindrical surface is fitted on the positioning surface in step 1, and then the outer surfaces of the upper clamping card plate and the lower clamping card plate are clamped by a chuck;

[0017] Step 4: mill the right axial end of the bar. First, mill the external thread on the surface used for external thread processing on the thin-walled liner-type parts in step 1, then mill a countersink on the right axial end face of the bar, and finally mill the right axial end face of the bar.

[0018] As a clamping method for turning of cylindrical parts, inner hole positioning and clamping are generally used for processing. However, as for the processing of thin-walled liner parts, it is necessary to prevent the deformation of the parts due to clamping while ensuring the dimension H from the center of the radial spherical hole to the end face of the part. Therefore, the clamping method of inner hole tension is not feasible. However, as long as any part of the thin-walled liner parts is positioned, the parts will be deformed. The processing of such parts has always been a difficult problem in the industry. For the processing of parts, positioning and clamping are a process that must be performed, and the parts cannot be processed in a free state. For thin-walled liner parts, their structural rigidity is originally very poor, and no matter which order is adopted, the deformation of the parts is inevitable. Therefore, reducing the deformation is the primary consideration in the positioning and clamping design, that is, try to clamp and process all the countersunk holes, threads and end faces of thin-walled liner parts at one time, control the deformation to the minimum, and then cooperate with the order of processing parts and reasonable cutting parameters to obtain the processing effect with the minimum deformation.

[0019] Aiming at the processing of thin-walled liner parts, the present invention adopts a tensioning processing fixture design concept to achieve the positioning, fixing and clamping of the parts, enhance the rigidity of the parts, and also realize the one-time clamping processing of the external thread, countersunk hole and the countersunk hole end face.

[0020] According to the characteristics and precision requirements of thin-walled liner parts processing, the present invention has the following characteristics:

[0021] 1. Thin-walled liner parts are initially positioned on the fixture body and are in a free state without compression deformation.

[0022] 2. Use positioning protrusions to axially position thin-walled liner parts.

[0023] 3. Use the upper clamping plate and the lower clamping plate to fit the outer cylindrical surface of thin-walled liner parts to increase the thickness and rigidity while preventing the parts from being deformed due to the clamping force of the chuck jaws.

[0024] 4. The size from the center of the positioning protrusion to the end face of the pallet is fixed. During processing, the supporting surface (i.e., the outer surface) of the pallet is clamped with the three-jaw chuck to achieve reliable positioning of the parts.

[0025] Compared with the prior art, the present invention abandons the traditional inner hole tensioning clamping, and instead adopts a combined clamp to clamp from the outer cylindrical surface of thin-walled liner parts, and cooperates with the positioning protrusion on the clamp to perform axial limiting. Finally, after one-time clamping, the processing of the external thread, end face and countersunk hole is completed, the deformation is small, and the roundness meets the design requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a part diagram of a thin-walled liner part in the present invention;

[0027] Figure 2 It is a schematic diagram of a processing fixture of the present invention;

[0028] Figure 3 It is a schematic diagram of the state of the thin-walled liner parts clamped on the processing fixture in the present invention;

[0029] In the figure, 1-upper clamping plate, 2-lower clamping plate, 3-positioning protrusion, 4-clamping surface. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to common technical knowledge and customary means in the field are included in the scope of the present invention.

[0031] The present invention analyzes the main reasons for the deformation of thin-walled liner parts: the compression force of thin-walled liner parts in the clamping state and the internal stress of the parts during processing cause deformation due to stress release after the parts are released. After obtaining the main reasons for deformation, the present invention designs the following Figure 2 The processing fixture shown is suitable for thin-walled liner parts, and the processing fixture includes an upper clamping plate 1 and a lower clamping plate 2. The upper clamping plate 1 includes a first cylindrical surface, which is half of a complete cylindrical surface; the lower clamping plate 2 includes a positioning protrusion 3 and a second cylindrical surface, the positioning protrusion 3 is cylindrical and located at one end of the second cylindrical surface, the second cylindrical surface is half of a complete cylindrical surface, and the second cylindrical surface of the lower clamping plate 2 and the first cylindrical surface of the upper clamping plate 1 are spliced ​​together to form a complete cylindrical inner hole, and the axis of the cylindrical inner hole is perpendicular to the axis of the positioning protrusion 3. The outer surface of one end of the upper clamping plate 1 is also provided with an annular edge coaxial with the first cylindrical surface; the outer surface of the end of the lower clamping plate 2 away from the positioning protrusion 3 is also provided with an annular edge coaxial with the second cylindrical surface.

[0032] This set of processing fixtures adopts the combination of upper clamping plate 1 and lower clamping plate 2 to clamp the outer surface of thin-walled liner parts. The parts are located in the part positioning inner hole formed by the upper clamping plate 1 and the lower clamping plate 2. Among them, a radial (perpendicular to the axis of the countersunk hole) positioning protrusion 3 is designed at the end of the lower clamping plate 2. This positioning protrusion 3 is used to axially position the thin-walled liner parts. The size from the center of the positioning protrusion 3 to the end face of the clamp is fixed and in a tensioned state. During processing, the outer surface ( Figure 2 The clamping surface 4) in the chuck is fitted with the three-jaw chuck, so that thin-walled bushing parts can be reliably positioned without shaking.

[0033] pass Figure 2The processing fixture design in the process solves the two difficult problems of poor rigidity and unreliable positioning in the processing of thin-walled liner parts. At present, the traditional solution is to use open bushings for clamping to reduce the clamping deformation of parts. However, the diameters of both ends of thin-walled liner parts are larger than the middle, and there are strict dimensional requirements for the end face of the thin-walled liner parts to the center of the radial spherical hole at the other end. The use of general open bushings cannot meet the requirements of part processing. This is because the processing batch size of thin-walled liner parts is large, and the efficiency of piece-by-piece tool setting is very low.

[0034] When processing thin-walled liner parts, follow the steps below:

[0035] Step 1: Using a bar as a blank, clamping the left end of the bar in the axial direction, turning the outer cylindrical surface of the bar to obtain two sections of outer cylindrical surfaces with different diameters, wherein the outer cylindrical surface with a larger diameter is used as a surface for external thread processing on thin-walled liner parts, and the outer cylindrical surface with a smaller diameter is used as a positioning surface for countersink processing on thin-walled liner parts;

[0036] Step 2: Clamp the right end of the bar in the axial direction and mill the left end of the bar in the axial direction to obtain a radial spherical hole on a thin-walled liner-like part;

[0037] Step 3, using the aforementioned processing fixture, wherein the first cylindrical surface of the upper clamping card plate 1 is fitted on the positioning surface in step 1, and the positioning protrusion 3 of the lower clamping card plate 2 is inserted into the radial spherical hole in step 2, while ensuring that the second cylindrical surface is fitted on the positioning surface in step 1, and then the outer surfaces of the upper clamping card plate 1 and the lower clamping card plate 2 are clamped by a chuck;

[0038] Step 4: Mill the right end of the bar axial direction. First, mill the external thread on the surface of the thin-walled liner part used for external thread processing in step 1 ( Figure 1 M22), and then mill a countersink on the right end face of the bar (to ensure Figure 1 The middle diameter φA and depth B), finally milling the right end face of the bar axial direction (to ensure Figure 1 Dimension H).

[0039] The present invention adopts Figure 3 The clamping and fixing method shown in the figure can not only ensure the final size of the thin-walled liner parts in this state, but also meet the requirement of non-deformation during processing of the parts. Through the milling test of thin-walled liner parts, the roundness change of the reference outer circle of the parts after processing is only 0.002mm to 0.003mm. It can be seen that the processing fixture design of the present invention is feasible and significantly reduces the deformation of the parts during processing. It has a high promotion and reference value for similar thin-walled parts processing.

[0040] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For the ordinary technical personnel in the field, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A processing fixture for thin-walled liner parts, characterized in that: include: An upper pressing clamping plate (1), the upper pressing clamping plate (1) comprising a first cylindrical surface, the first cylindrical surface being half of a complete cylindrical surface; The lower clamping card plate (2) comprises a positioning protrusion (3) and a second cylindrical surface, the positioning protrusion (3) is cylindrical and is located at one end of the second cylindrical surface, the second cylindrical surface is half of the complete cylindrical surface, and the second cylindrical surface of the lower clamping card plate (2) and the first cylindrical surface of the upper clamping card plate (1) are spliced ​​together to form a complete cylindrical inner hole, and the axis of the cylindrical inner hole is perpendicular to the axis of the positioning protrusion (3).

2. A processing fixture for thin-walled liner parts according to claim 1, characterized in that: The outer surface of one end of the upper clamping clamp (1) is also provided with an annular edge coaxial with the first cylindrical surface; An outer surface of one end of the lower clamping plate (2) away from the positioning protrusion (3) is also provided with an annular edge coaxial with the second cylindrical surface.

3. A method for processing thin-walled liner parts, characterized in that: The following steps are involved: Step 1: Using a bar as a blank, clamping the left end of the bar in the axial direction, turning the outer cylindrical surface of the bar to obtain two sections of outer cylindrical surfaces with different diameters, wherein the outer cylindrical surface with a larger diameter is used as a surface for external thread processing on thin-walled liner parts, and the outer cylindrical surface with a smaller diameter is used as a positioning surface for countersink processing on thin-walled liner parts; Step 2: Clamp the right end of the bar in the axial direction and mill the left end of the bar in the axial direction to obtain a radial spherical hole on a thin-walled liner-like part; Step three, using the processing fixture described in claim 1, wherein the first cylindrical surface of the upper clamping clamp (1) is fitted on the positioning surface in step one, and the positioning protrusion (3) of the lower clamping clamp (2) is inserted into the radial spherical hole in step two, while ensuring that the second cylindrical surface is fitted on the positioning surface in step one, and then a chuck is used to clamp the outer surfaces of the upper clamping clamp (1) and the lower clamping clamp (2); Step 4: mill the right axial end of the bar. First, mill the external thread on the surface used for external thread processing on the thin-walled liner-type parts in step 1, then mill a countersink on the right axial end face of the bar, and finally mill the right axial end face of the bar.

Images