Composite tube shell high-precision shape and position tolerance processing technology

Abstract

The present application relates to the technical field of slow wire mechanical processing, and provides a composite pipe shell high-precision shape and position tolerance processing technology, which comprises the following steps: processing a pre-hole in the composite pipe shell to release stress; measuring the coaxial degree shape and position tolerance of the composite pipe shell after pre-processing; hydrogen burning straightening of the composite pipe shell to eliminate stress; measuring the shape and position tolerance of the composite pipe shell after straightening, and recording the position change of the high and low point positions of the coaxial degree measurement on the pole shoe; and adjusting the center position of the composite pipe shell processing according to the recorded high and low point positions of the coaxial degree. Through the process mode of increasing the pre-processing inner diameter, measuring the shape and position tolerance, hydrogen burning straightening of the composite pipe shell, measuring the shape and position tolerance after straightening, and adjusting the processing center position during the composite pipe shell machining process, the composite pipe shell reaches high-precision shape and position tolerance precision, and the coaxial degree reaches Φ0.01mm.

Description

Technical Field

[0001] This invention relates to the field of wire EDM machining technology, specifically a high-precision form and position tolerance machining process for composite tube shells. Background Technology

[0002] Traveling wave tubes (TWTs), as amplifying devices for vacuum microwave power, possess advantages such as wide bandwidth, high gain, and high output power. The slow-wave system, as a crucial component of the TWT, plays a role in standing wave interaction and forming the electron beam trajectory channel structure. To meet the performance requirement of achieving an electron beam flux exceeding 98% in a certain wavelength band, an integrated composite tube-shell slow-wave structure was designed, such as... Figure 1 The diagram shows a composite tube shell structure in a traveling wave tube. Its characteristic is that the length-to-diameter ratio (L:ΦD1) is 45. The composite tube shell is usually assembled and welded from parts such as magnetic screen, pole shoe, and connecting ring. It is necessary to ensure that the coaxiality between the inner hole of the composite tube shell and the reference meets the requirement of φ0.01mm after the final processing is completed. In order to realize the processing of a one-piece composite tube shell with a large length-to-diameter ratio, it is necessary to improve the coaxiality form and position tolerance accuracy during the processing.

[0003] Currently, due to factors such as straightness differences exceeding 0.04mm in composite tube shell components, internal stress in the composite tube shell, and correction errors between the composite tube shell and tooling, the coaxiality of composite tube shells with a length-to-diameter ratio of 45 after one-time wire EDM machining is measured to be Φ0.06~Φ0.1mm. Therefore, this invention proposes a high-precision form and position tolerance machining process for composite tube shells. Through process paths such as pre-machining the inner diameter, measuring the form and position tolerance dimensions, hydrogen burning to straighten the composite tube shell, measuring the form and position tolerance after straightening, adjusting the center position of the composite tube shell, and finally machining, the problem of excessive coaxiality form and position tolerance caused by one-time machining can be solved, enabling the form and position tolerance of the integrated composite tube shell to achieve high precision and meet the final coaxiality requirement of Φ0.01mm. Summary of the Invention

[0004] This invention provides a high-precision form and position tolerance machining process for composite tube shells to solve the problem of excessive coaxiality form and position tolerances caused by one-time machining in the prior art.

[0005] The technical solution of this invention is as follows:

[0006] A high-precision form and position tolerance machining process for composite tube shells, comprising a magnetic shield, pole shoes, connecting rings, and adapters that make up the composite tube shell, is characterized by including the following steps:

[0007] S1: Pre-drilling holes inside the composite tube shell to release stress;

[0008] S2: Measure the coaxiality and form and position tolerances of the pre-processed composite tube shell;

[0009] S3: Hydrogen-burning straightens the composite tube shell, while simultaneously eliminating stress;

[0010] S4: Measure the form and position tolerances of the straightened composite tube shell and record the position changes of the high and low points of the coaxiality measurement on the pole shoe;

[0011] S5: Adjust the center position of the composite tube shell according to the recorded high and low points of coaxiality;

[0012] In S1, the composite tube shell is welded to the positioning core rod with ΦD as the positioning and clamping reference. The tooling center is corrected to ensure the uniformity of the reference surface, which is conducive to improving the coaxiality of the composite tube shell. Then, the ΦD1 dimension is processed by cutting twice with a slow wire EDM machine, and a 0.1-0.3mm allowance is left during processing to allow for subsequent position adjustment.

[0013] In S2, the composite tube shell is held in place by the pins at both ends of the coaxiality measuring instrument, and the outer contour surface of the pole shoe is measured with a dial indicator. The coaxiality measurement data is read by rotating the composite tube shell and recorded in the inspection card.

[0014] In S3, the mold used during the welding of the composite tube shell is used to straighten the composite tube shell in the hydrogen furnace. This can eliminate the welding stress inside the composite tube shell and achieve the straightening purpose using the mold.

[0015] In S4, the outer contour surface of the pole shoe is measured again with a dial indicator, the composite tube shell is rotated to read the coaxiality measurement data, and the positions of the highest and lowest points of coaxiality on the outer circle contour of the pole shoe are marked during the measurement to provide adjustment reference for subsequent operations.

[0016] In S5, the composite tube shell is welded to the positioning core rod with ΦD as the positioning and clamping reference, the tooling center is corrected, and the position B, where the coaxiality high point exists, is adjusted in the same direction according to the measurement results in S4.

[0017] Preferably, the wire EDM machine in S1 uses a wire with a diameter of 0.1 mm, the wire material is molybdenum wire, and the feed speed is 0.002-0.003 mm.

[0018] Preferably, in step S2, the dial indicator head gently contacts the surface being measured, compressing the head by 1-2 mm, and the composite tube shell is rotated 2-3 times, with the average value recorded.

[0019] Preferably, the temperature inside the hydrogen furnace in S3 is 450℃~480℃.

[0020] Preferably, the mold in S3 includes a welding upper mold and a welding lower mold.

[0021] Preferably, in step S5, the adjustment distance Δ is 1 / 2 × coaxiality dimension.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention solves the problem of excessive coaxiality in the machining of composite tube shells by employing a method of pre-machining the inner diameter, measuring the coaxiality after pre-machining, straightening the composite tube shell by hydrogen burning, measuring the coaxiality after straightening, and adjusting the position of the machining center. This ensures that the overall coaxiality of the composite tube shell reaches Φ0.01mm, meeting the design requirements. This method plays a crucial role in subsequent operations such as the alignment and assembly of the collecting electrode components, the alignment and assembly of the electron gun components, and the alignment and assembly of the high-frequency internal clamping rod and the spiral. Under the premise of high-precision assembly requirements for traveling wave tubes, the process path in this invention can effectively improve the overall performance of the traveling wave tube. Attached Figure Description

[0024] Figure 1 This is a structural diagram of the composite tube shell of the present invention;

[0025] Figure 2 This is a schematic diagram illustrating the measurement of coaxiality of pre-machined holes according to the present invention;

[0026] Figure 3 This is a schematic diagram of the straightening composite tube shell of the present invention;

[0027] Figure 4 This is a schematic diagram illustrating the measurement of coaxiality deviation points according to the present invention;

[0028] Figure 5 This is a flowchart of the process of the present invention.

[0029] In the picture:

[0030] 1. Ejector shoe; 2. Ejector pin; 3. Dial indicator; 4. Upper mold (welded); 5. Lower mold (welded). Detailed Implementation

[0031] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0032] Example 1:

[0033] A high-precision form and position tolerance machining process for composite tube shells includes the following steps:

[0034] Step 1: Pre-drill holes inside the composite tube shell to release stress; such as Figure 1 As shown, the composite tube shell is welded to the positioning core rod with ΦD as the positioning and clamping reference. The tooling center is corrected to ensure the uniformity of the reference surface, which is conducive to improving the coaxiality of the composite tube shell. Then, the ΦD1 dimension is processed by cutting twice with a slow wire EDM machine, and a radial allowance of 0.1-0.3mm is left during processing to leave machining allowance for subsequent position adjustment.

[0035] Step 2: Measure the coaxiality and geometric tolerances of the pre-machined composite tube shell; such as... Figure 2 As shown, with ΦD1 as the reference axis, the two pins 2 of the coaxiality measuring instrument are pressed against the two ends of the pre-hole of the composite tube shell, and the dial indicator 3 is gently touched to the outer contour surface of the pole shoe 1, so that the dial indicator has a compression of 1-2mm. The composite tube shell is slowly rotated 2-3 times and the coaxiality measurement data is read and recorded in the inspection card. The above steps are repeated to measure at different positions of the workpiece to obtain multiple data points and calculate the average value.

[0036] Step 3: Straighten the composite tube shell by burning hydrogen, and simultaneously eliminate stress; such as Figure 3 As shown, the composite tube shell is straightened in a hydrogen furnace at 450℃~480℃ using the molds used during welding. The composite tube shell is placed in the hydrogen furnace for preheating. The preheating temperature should be lower than the phase transformation temperature of the material to avoid excessive thermal stress. During preheating, the deformation of the composite tube shell is carefully observed to prepare for subsequent straightening operations. After the composite tube shell is preheated to a suitable temperature, the upper welding mold 4 and the lower welding mold 5 are quickly installed onto the tube shell, ensuring a tight fit between the molds and the composite tube shell to avoid new deformation. The straightening process utilizes the supporting force of the molds and... Due to the thermoplasticity of the composite tube shell material, the composite tube shell is straightened. During the straightening process, the force should be applied gradually to avoid applying excessive force at once, which could cause the tube shell to crack. After straightening, the composite tube shell is kept at a certain temperature in the hydrogen furnace for a period of time to allow the internal structure of the composite tube shell to fully stabilize. After the heat preservation is completed, the composite tube shell is removed from the hydrogen furnace and allowed to cool naturally or under controlled cooling. During the cooling process, rapid temperature changes should be avoided to prevent the generation of new thermal stress. This process can eliminate the welding stress inside the composite tube shell and achieve the purpose of straightening using molds.

[0037] Step 4: Measure the form and position tolerances of the straightened composite tube shell and record the changes in the high and low points of the coaxiality measurement on pole shoe 1; gently touch the outer contour surface of pole shoe 1 with the dial indicator 3 again, slowly rotate the tube shell 2-3 times and read the coaxiality measurement data. Unlike S2, it is necessary to mark the positions of the highest and lowest points of coaxiality on the outer circle contour of pole shoe 1 during the measurement. This method is to provide an adjustment reference for subsequent operations.

[0038] Step 5: Based on the recorded high and low points of coaxiality, adjust the center position of the processed composite tube shell; for example... Figure 4 As shown, the positioning and clamping method is consistent with that in S1, with Figure 1Using ΦD as the reference axis, the center position of the tooling is corrected. Based on the measurement results in S4, the coaxiality error is calculated. The coaxiality is adjusted in the same direction at position B where the high point of coaxiality exists. The adjustment distance Δ is 1 / 2 × the coaxiality dimension. For example, if the overall coaxiality of the composite tube shell is Φ0.03mm at position B, then the adjustment Δ is 0.015mm at position B. The adjusted position is used as the center position for processing the composite tube shell. Through this process, the form and position tolerance accuracy of the composite tube shell can be effectively improved to meet the design requirement of Φ0.01mm.

[0039] like Figure 1-5 As shown, this embodiment solves the problem of excessive coaxiality in the processing of composite tube shells by pre-processing the inner diameter, measuring the coaxiality after pre-processing, straightening the composite tube shell by hydrogen burning, measuring the coaxiality after straightening, and adjusting the position of the processing center. This makes the overall coaxiality of the tube shell reach Φ0.01mm, which meets the design requirements.

[0040] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-precision form and position tolerance machining process for composite tube shells, comprising pole shoes (1) constituting the composite tube shell, characterized in that: Includes the following steps: S1: Pre-drilling holes inside the composite tube shell to release stress; S2: Measure the coaxiality and form and position tolerances of the pre-processed composite tube shell; S3: Hydrogen-burning straightens the composite tube shell, while simultaneously eliminating stress; S4: Measure the form and position tolerances of the straightened composite tube shell and record the position changes of the high and low points of the coaxiality measurement on the pole shoe (1); S5: Adjust the center position of the composite tube shell according to the recorded high and low points of coaxiality; S1 includes: welding the composite tube shell to the positioning core rod with ΦD as the positioning and clamping reference, correcting the tooling center, ensuring the uniformity of the reference surface, which is conducive to improving the coaxiality of the composite tube shell, and then processing the ΦD1 dimension by cutting twice with a slow wire EDM machine, and leaving a radial allowance of 0.1-0.3mm during processing to leave a machining allowance for subsequent position adjustment. The S2 includes: using the pins (2) at both ends of the coaxiality measuring instrument to hold the composite tube shell, using the dial indicator (3) to measure the outer contour surface of the pole shoe (1), rotating the composite tube shell to read the coaxiality measurement data, and recording it in the inspection card; The S3 includes: using the mold used during the welding of the composite tube shell to perform straightening treatment of the composite tube shell in the hydrogen furnace, which can both eliminate the welding stress inside the composite tube shell and achieve the purpose of straightening using the mold. The S4 includes: measuring the outer contour surface of the pole shoe (1) again with a dial indicator (3), rotating the composite tube shell to read the coaxiality measurement data, and marking the positions of the highest and lowest points of coaxiality on the outer contour of the pole shoe (1) during the measurement, so as to provide adjustment reference for subsequent operations; S5 includes: welding the composite tube shell to the positioning core rod with ΦD as the positioning and clamping reference, correcting the tooling center, and adjusting it in the same direction at position B where the coaxiality high point exists, according to the measurement results in S4.

2. The high-precision form and position tolerance machining process for composite tube shells as described in claim 1, characterized in that: The slow wire EDM machine in S1 uses 0.1mm wire, the wire material is molybdenum wire, and the feed speed is 0.002-0.003mm.

3. The high-precision form and position tolerance machining process for composite tube shells as described in claim 1, characterized in that: In S2, the dial indicator (3) lightly touches the surface being measured, so that the dial indicator has a compression of 1-2 mm. Rotate the composite tube shell 2-3 times and record the average value.

4. The high-precision form and position tolerance machining process for composite tube shells as described in claim 1, characterized in that: The temperature inside the hydrogen furnace in S3 is 450℃~480℃.

5. The high-precision form and position tolerance machining process for composite tube shells as described in claim 1, characterized in that: The mold in S3 includes a welding upper mold (4) and a welding lower mold (5).

6. The high-precision form and position tolerance machining process for composite tube shells as described in claim 1, characterized in that: In S5, the adjusted distance Δ value is 1 / 2 × coaxiality dimension.

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