Processing method for hollow parts

Abstract

The present invention relates to the technical field of mechanical manufacturing, and particularly to a processing method for a hollow part. The processing method includes: arranging a positioning block parallel to the built-in parallel plane of the target hollow part outside the feed end of the processing die; based on the positioning block, completing the alignment of the preformed hollow part blank corresponding to the built-in parallel plane of the target hollow part; and processing the aligned preformed hollow part blank to obtain the built-in parallel plane. By arranging a positioning block parallel to the radial projection of the built-in parallel plane, the present invention realizes the visual positioning and correction of the plane to be processed; at the same time, by optimizing the positioning accuracy of the positioning block with an optoelectronic autocollimator, the positioning accuracy of the built-in parallel plane is further improved, and the processing accuracy is greatly improved compared with the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material manufacturing, and particularly relates to a processing method for a hollow part. Background Art

[0002] There is a wide demand for high-precision internally shaped hollow parts in the aviation field. Especially for a new generation of aviation materials represented by light alloys (such as magnesium-aluminum alloy), materials such as light alloys cannot be welded or the welding precision is difficult to control, and the casting process is difficult to meet the precision requirements for internal shaped structures. Currently, the production of light alloy hollow parts mainly relies on machine tool processing (turning, milling, etc.).

[0003] For the internally parallel planes parallel to the axis in high-precision hollow parts, a common processing method is: fixing the preformed hollow part blank and adjusting the coordinate position of the tool for processing; this method has defects such as poor precision and difficult calibration due to the long tool travel, complex calibration, and program control. Another common processing method: fixing the preformed hollow part blank on a rotary table, restricting the tool to a limited area, and sequentially placing different areas of the preformed hollow part blank within the limited processing area of the tool by rotating the rotary table; this method generally needs to determine the rotation angle of the rotary table with the help of the angle scale of the rotary table to complete the alignment of the plane to be processed. Currently, the indexing precision of a vertical rotary table in the prior art is 0.01°, but due to factors such as superposition of part deformation and cumulative errors in other directions during the processing, it is not easy to ensure the angular tolerance between combined planes, the risk of out-of-tolerance is relatively large, the yield rate is low, and it still cannot meet the requirements of high-precision processing. Currently, there is an urgent need in the market for a processing device and method for the internally parallel planes parallel to the axis in high-precision hollow parts. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a processing method for a hollow part to solve at least one of the problems such as low yield rate, low processing precision, and great influence by the precision of the machine tool itself in the prior art problems.

[0005] The object of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a processing method for a hollow part, including:

[0007] A positioning block parallel to the internally parallel plane of the target hollow part is arranged outside the feed end of the processing die;

[0008] Based on the positioning block, the preformed hollow part blank is aligned with the internally parallel plane of the target hollow part corresponding to the positioning block;

[0009] The preformed hollow part blank after alignment is processed to obtain the internally parallel plane.

[0010] Preferably, the processing of the preformed hollow part blank includes: restricting the machining range of the machining tool to a fixed area on one side of the center relative to the preformed hollow part blank.

[0011] Preferably, the rotation angle of the vertical rotary table fixedly connected to the preformed hollow part blank is adjusted to achieve the machining of different regions of the preformed hollow part blank.

[0012] Preferably, the positioning blocks parallel to the built-in parallel planes of the target hollow parts are set, including: determining the angle between the positioning blocks corresponding to the built-in parallel planes of the two target hollow parts according to the angle of the radial projection of the built-in parallel planes of the two target hollow parts, and sequentially setting each positioning block according to the angle of the positioning blocks.

[0013] Preferably, setting the positioning blocks parallel to the built-in parallel planes of the target hollow parts includes the following steps:

[0014] Taking the geometric center of the outer side of the feed end of the machining die as the origin, taking the radial plane of the machining die as the x'z' plane, constructing an x'y'z' three-axis coordinate system, and setting the first positioning block as the reference positioning block in the x'z' plane;

[0015] Obtaining the included angle α between the first positioning block and the second positioning block, and fixedly installing a multi-faceted prism in the central area of the horizontal rotary table; rotating the multi-faceted prism by α degrees, and setting the second positioning block in the x'z' plane area, wherein the included angles between the second positioning block and the x' axis and the z' axis are the same as those of the first positioning block;

[0016] Based on the included angle between the first positioning block and the Mth positioning block, rotating the multi-faceted prism by the included angle between the first positioning block and the Mth positioning block, and setting the Mth positioning block; M is a positive integer greater than or equal to 3.

[0017] Preferably, a pre-machining process of the preformed hollow part blank is also included between setting the positioning blocks parallel to the built-in parallel planes of the target hollow parts and aligning with the built-in parallel planes.

[0018] Preferably, the pre-machining process includes the following steps:

[0019] Establishing a reference line and obtaining the included angle α0 between the reference line and the first positioning block;

[0020] Fixing the preformed hollow part blank on the rotary table through the machining die, and obtaining the inclination angle α of the reference line with respect to the horizontal plane - , based on the included angle α0 and the angle α - Obtaining the rotation angle α of the rotary table required for aligning the first positioning block t1 ; based on α t1 Completing the preliminary alignment of the first built-in parallel plane; specifically, αt1 Satisfy: α t1 = α - + 90° - α0;

[0021] Machining with allowance for the mold to be machined that has completed the preliminary alignment of the first built-in parallel plane;

[0022] Based on α t1 and the angle α1 between the first target plane and the second target plane to obtain the rotation angle α of the rotary table required for the alignment of the second positioning block t2 Based on α t1 and the angle α2 between the first built-in parallel plane and the third built-in parallel plane to obtain the rotation angle α of the rotary table required for the alignment of the third positioning block t3 ..., based on α t and the angle α between the Nth built-in parallel plane and the first built-in parallel plane N to obtain the rotation angle α of the rotary table required for the alignment of the Nth positioning block tN .

[0023] Preferably, between the preprocessing process and the alignment of the built-in parallel plane, it also includes the heat treatment process of the preformed hollow part blank.

[0024] Preferably, the heat treatment of the preformed hollow part blank includes the following steps:

[0025] At 120 ± 10 °C, heat treatment for 2h to 6h, and then air-cooled to room temperature;

[0026] At - 50 ± 5 °C, process for 1h to 3h, and place at room temperature to rise;

[0027] At 120 ± 10 °C, heat treatment for 2h to 6h, and then air-cooled or furnace-cooled to room temperature.

[0028] Preferably, the machining program for obtaining the built-in parallel plane is generated by programming software based on the three-dimensional model of the preformed hollow part blank and the three-dimensional model of the machined part finished product.

[0029] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0030] (1) The present invention transmits the angular relationship of the radial projection of the axially parallel built-in parallel plane to the angular relationship of the corresponding positioning block by setting a positioning block parallel to the radial projection of the axially parallel built-in parallel plane of the target hollow part, thereby decomposing the processing of the axially parallel built-in parallel plane into two parts: aligning and positioning the axially parallel built-in parallel plane and cutting the axially parallel built-in parallel plane. Therefore, the present invention does not need to add a positioning function module when designing the processing program. Compared with the prior art, the workpiece to be processed is fixed and only the processing tool is used for cutting, which reduces the complexity of program design and the elongation of the processing tool, and improves the processing accuracy and reliability.

[0031] (2) The present invention converts the alignment of the axially parallel built-in parallel planes into the horizontal adjustment of the corresponding positioning blocks, and converts the positional relationship of the built-in parallel planes of the target hollow part that is abstract and invisible before processing into the angular relationship between the positioning blocks and between the positioning blocks and the horizontal plane. Before processing the built-in parallel planes, the built-in parallel planes of the target hollow part can be corrected by measuring and correcting the positioning blocks, thereby improving the processing accuracy.

[0032] (3) The present invention uses a rotating method for the preformed hollow part blank to realize processing of different areas of the preformed hollow part blank. The tool only needs to move within a local range on one side of the area to be processed, thereby reducing the tool processing stroke. Compared with the processing method in the prior art in which the processed part is fixed and the tool is moved to each processing area, the cumulative error caused by the increase in the tool stroke is reduced, thereby improving the accuracy.

[0033] (4) The present invention sets a positioning block parallel to the radial projection of the built-in axial parallel plane, and uses the parallel transmission law to convert the angular relationship of the built-in parallel plane of the target hollow part on the radial plane projection into the angular relationship between the positioning blocks; further, the present invention uses a photoelectric autocollimator to correct the angular relationship between the positioning blocks, which improves the accuracy compared to the angle scale provided by the vertical rotary table, thereby achieving precise positioning of the built-in parallel plane of the target hollow part.

[0034] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0036] Figure 1 Schematic assembly diagram of a hollow part with axially parallel internal planes and a processing die from a 45° top view perspective in an embodiment of the present invention;

[0037] Figure 2 Schematic diagram of a hollow part with axially parallel internal planes from a 45° top view perspective in an embodiment of the present invention;

[0038] Figure 3 Cross-sectional view of plane A - A of a hollow part with axially parallel internal planes in an embodiment of the present invention;

[0039] Figure 4 Cross-sectional view of plane A - A of a blank of a hollow part with axially parallel internal planes in an embodiment of the present invention;

[0040] Figure 5 Schematic assembly diagram of an unformed hollow part with axially parallel internal planes, an external pressing plate, and a positioning block from a 45° top view perspective in an embodiment of the present invention;

[0041] Figure 6 Schematic diagram of a processing device and its installation method for a hollow part with axially parallel internal planes in an embodiment of the present invention;

[0042] Figure 7 Flowchart of a processing method for a hollow part with axially parallel internal planes in an embodiment of the present invention;

[0043] Figure 8 Flowchart of a positioning method for axially parallel internal planes of a hollow part in an embodiment of the present invention.

[0044] Reference numerals:

[0045] External pressing plate 1; Tie rod 2; Bottom fixing part 3; Hollow part 4; Rotary table 5; Machine tool platform 6; Machine tool spindle 7, Machining tool 8; Positioning block 101; First positioning block 1011; Second positioning block 1012; Central hole 102; Edge solid area 103; Tie rod mounting hole 104; First positioning through - hole 105; Positioning pin 106; Second positioning hole 401; Axially parallel internal parallel planes 402; Internal parallel planes of the target hollow part 402'; First internal parallel plane 4021; Second internal parallel plane 4022; First target plane 4021'; Second target plane 4022'; Part body 403; Machining range of the machining tool 405. Detailed implementation manners

[0046] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0047] To clearly explain the technical solutions of the present invention, the following technical terms are further defined:

[0048] Alignment:

[0049] The present invention defines alignment as the state where the plane to be machined is parallel to the horizontal plane.

[0050] The included angle between two straight lines l1 and l2:

[0051] The angle turned when line l1 is rotated counterclockwise until it coincides with l2.

[0052] Currently, in the prior art, the indexing accuracy of a vertical rotary table is higher than 0.01°. Limited by the accuracy of the vertical rotary table, it is difficult to further improve the horizontal alignment accuracy of the plane to be machined. To solve the above problems, the present invention provides a processing device and a processing method for an internally parallel plane in the parallel axis direction of a high-precision hollow part that do not rely on the indexing accuracy of the rotary table.

[0053] The present invention provides a processing method for a hollow part, as Figure 7 shown, including the following steps:

[0054] Step 1: A positioning block parallel to the internally parallel plane of the target hollow part is arranged outside the feed end of the processing die;

[0055] Specifically, one end of the processing die is fixedly connected to the vertical rotary table, and the other end is the feed end. The included angle of the positioning blocks corresponding to the parallelism with the internally parallel planes of the two target hollow parts is confirmed according to the included angle of the radial projections of the internally parallel planes of the two target hollow parts, and each positioning block is arranged in sequence according to the included angle of the positioning blocks.

[0056] Specifically, as Figure 1As shown in the figure, the processing device includes: an external pressing plate 1, a pull rod 2, a bottom fixing member 3, a vertical rotary table 5, a machine tool platform 6, a machine tool spindle 7, and a processing tool 8; the external pressing plate 1 is located at one end of the pull rod, the bottom fixing member 3 is located at the other end of the pull rod 2, the external pressing plate 1 and the bottom fixing member 3 are fixedly connected through the pull rod 2, and a fixing area for clamping and fixing the preformed hollow part blank is provided between the external pressing plate 1 and the bottom fixing member 3; a positioning block 101 parallel to the built-in axial parallel plane of the preformed hollow part blank is provided at one end of the external pressing plate 1 away from the bottom fixing member 3; the vertical rotary table 5 is fixedly connected to the end of the bottom fixing member 3 facing away from the external pressing plate 1; one side of the machine tool platform 6 is movably connected to the vertical rotary table 5, and the other side of the machine tool platform 6 is movably connected to the machine tool spindle 7; the processing tool 8 is arranged at the end of the machine tool spindle 7 on the side close to the external pressing plate 1.

[0057] During implementation, a first positioning block 1011 is set as the reference positioning block, and the positioning blocks are set according to the angles of the remaining positioning blocks relative to the reference positioning block.

[0058] It should be noted that there are multiple installation positions for the positioning blocks that satisfy the angular relationship with the reference positioning block, and all the straight lines where the installation positions are located are parallel to each other and have the same angle with the reference positioning block; a installation position without obstacles is selected on the outer side of the external pressing plate 1 to set the positioning block, and the positioning block set at this installation position should not obstruct the other structures and functions on the same side of the external pressing plate 1. Based on this, the angle between any two positioning blocks provided on the external pressing plate 1 is the same as the angle between the projections of the corresponding built-in parallel planes in the radial plane; the angular relationship of the positioning blocks set by the above method corresponds to the angle between the projections of the axially parallel built-in parallel planes to be processed in the radial plane, and the inclination angle of the built-in parallel plane of the target hollow part relative to the horizontal plane is converted into the angle between the positioning block and the horizontal plane.

[0059] Step 2: Based on the positioning blocks, complete the alignment of the preformed hollow part blank with the built-in parallel plane of the target hollow part corresponding to the positioning blocks;

[0060] Specifically, adjust the rotation angle of the vertical rotary table until the positioning block is horizontal. Based on the principle of parallel transfer, it is possible to horizontally place the built-in parallel plane of the target hollow part corresponding to the positioning block within the processing range of the processing tool, and complete the alignment of the built-in parallel plane of the target hollow part; the processing range of the processing tool is restricted to a fixed area on one side of the center of the relative hollow part through program control.

[0061] Step 3: Process the aligned preformed hollow part blank to obtain the built-in parallel plane; specifically, based on the processing program, the processing tool processes and removes the surplus material from the inner wall to the outer wall of the preformed hollow part blank to obtain the built-in parallel plane of the target hollow part.

[0062] On the one hand, the built-in parallel planes parallel to the axis to be machined are abstract and invisible before machining is completed, while the positioning blocks are concretely visible. The advantage of using the positioning blocks for zero adjustment in the present invention is that, compared with the prior art, the present invention converts the zero adjustment of the built-in parallel planes parallel to the axis to be machined into the horizontal adjustment of the corresponding positioning blocks, and the positioning blocks can be measured and corrected before machining the built-in parallel planes, so as to realize the correction of the built-in parallel planes parallel to the axis to be machined and improve the machining accuracy.

[0063] On the other hand, the machining error of the tool is proportional to its stroke. Compared with the prior art, the present invention adopts the rotation mode of the preformed hollow part blank to machine different regions of the preformed hollow part blank. The tool only needs to move within a local range on one side of the region to be machined, reducing the machining stroke of the tool. Compared with the way that the tool accumulatively moves between each machining region in the prior art, the cumulative error caused by the increase of the tool stroke is reduced, and the accuracy is improved.

[0064] Specifically, setting the positioning blocks of the built-in parallel planes parallel to the target hollow part on the outer side of the feed end of the machining die in step 1 includes the following steps:

[0065] S101: Taking the geometric center of the feed end of the machining die as the origin, taking the radial plane of the machining die as the x'z' plane, constructing an x'y'z' three-axis coordinate system, and setting the first positioning block 1011 in the x'z' plane as the reference positioning block;

[0066] Specifically, fixing the external pressing plate 1 coaxially with a group of first positioning through holes 105 that are centrosymmetric with respect to the geometric center of the external pressing plate 1 on the horizontal rotary table; taking the geometric center of the outer side surface of the feed end of the machining die as the origin, taking the center connection line of the first positioning through holes 105 in the initial position as the coordinate axis x' axis, establishing the coordinate axis z' axis in the plane of the horizontal rotary table in the initial position perpendicular to the x' axis direction, and taking the perpendicular line passing through the origin and perpendicular to the coordinate axes x' and z' as the y' axis; the first positioning block 1011 is arranged in the solid region outside the external pressing plate 1 perpendicular to the z' axis direction; it should be noted that the initial position is an arbitrarily selected position after the position of the external pressing plate 1 fixes the horizontal rotary table as the initial position. After constructing the coordinate system, the rotation of the horizontal rotary table has no influence on the coordinate system.

[0067] S102: Obtaining the included angle α between the first positioning block 1011 and the second positioning block 1012, and fixedly installing a multi-face prism in the central region of the horizontal rotary table; rotating the multi-face prism by α degrees, and setting the second positioning block 1012 in the x'z' plane, wherein the included angles between the second positioning block 1012 and the x' axis and the z' axis are the same as those of the first positioning block 1011; specifically, arranging the second positioning block 1012 in the solid region outside the external pressing plate 1 perpendicular to the z' axis direction;

[0068] S103: Rotate the multi-sided prism by the angle between the first positioning block and the M-th positioning block, and set the M-th positioning block based on the angle between the first positioning block and the M-th positioning block; M is a positive integer greater than or equal to 3.

[0069] It should be noted that S101 - S103 are implemented on a horizontal rotary table, which is different from the vertical rotary table described in steps 1 - 3: the rotation plane of the horizontal rotary table is set horizontally and is the table of a horizontal machining center; the rotation plane of the vertical rotary table is set perpendicular to the horizontal plane.

[0070] It should be noted that in order to ensure the consistency of the angular relationship relative to the first positioning block, the second positioning block, the third positioning block,..., the M-th positioning block are set in S102 and S103, and the rotation direction of the multi-sided prism is the same.

[0071] Specifically, in order to correct the positioning accuracy of the positioning block in the direction perpendicular to the z-axis, the first positioning block 1011 is set in the direction perpendicular to the z'-axis in S101, the second positioning block 1012 is set in the direction perpendicular to the z'-axis in S102, and the third positioning block,..., the M-th positioning block are set in S103, including using a dial indicator to correct the positioning accuracy of the positioning block in the direction perpendicular to the z-axis.

[0072] Specifically, it includes the following steps:

[0073] S1011: Set the positioning block in the direction perpendicular to the z'-axis;

[0074] S1012: Mount a dial indicator on the machine tool spindle and let the spindle translate along the x-axis, and fine-tune the angle of the positioning block according to the reading until the change in the reading of the dial indicator pointer is less than the threshold value when the dial indicator probe slides from one end to the other end on the positioning block, and it is determined that the positioning block is strictly perpendicular to the z'-axis.

[0075] It should be noted that in S1011, the positioning block can be set perpendicular to the z'-axis by visual judgment or angle measurement with an angle gauge; however, the positioning accuracy of the positioning block set by these two methods cannot meet the requirements of precision machining; therefore, it is necessary to further correct the perpendicular relationship between the positioning block and the z'-axis.

[0076] During implementation, in S1012, by mounting a dial indicator on the machine tool spindle, it is possible to achieve parallel movement along the x'-axis of the dial indicator coordinate axis, and the displacement probe of the dial indicator contacts a side to be measured of the positioning block; if the side to be measured is not parallel to the x'-axis of the coordinate axis, there is a displacement change of the displacement probe of the dial indicator on the side to be measured, resulting in a change in the reading of the dial indicator; if the side to be measured is parallel to the x'-axis of the coordinate axis, the change in the reading of the dial indicator cannot be detected or is 0.

[0077] Specifically, the side to be measured is: the side of the positioning block parallel to the y'-axis of the coordinate axis.

[0078] Specifically, the change in the indication of the dial indicator pointer is introduced to evaluate the parallelism between the side to be measured and the x'-axis of the coordinate axis: if η is less than 1%, it is determined that the alignment is completed; the change in the indication η satisfies: η = S max -S min , where S max is the maximum value of the indication of the dial indicator pointer, and S min is the minimum value of the indication of the dial indicator pointer.

[0079] Specifically, in S102, the included angle between the first positioning block 1011 and the second positioning block 1012 is the same as the included angle between the projections of the first target plane 4021' and the second target plane 4022' on the radial plane; among them, the first target plane 4021' is parallel to the first positioning block 1011; the second target plane 4022' is parallel to the second positioning block 1012.

[0080] Specifically, in S102, the multi-faceted prism rotates by α degrees, including precision correction of the rotation angle of the multi-faceted prism through an optoelectronic autocollimator.

[0081] Specifically, the optoelectronic autocollimator can measure the deflection angle between its emitted light and the received reflected light signal, and the measurement accuracy is higher than 0.8″; by adjusting the included angle between the optoelectronic autocollimator and the reflecting surface of the multi-faceted prism, when the indication of the optoelectronic autocollimator is 0, the reflecting surface of the multi-faceted prism is perpendicular to the emitted light direction of the optoelectronic autocollimator.

[0082] Specifically, in S102, the side surfaces of the multi-faceted prism are rectangular reflecting surfaces of the same size perpendicular to the horizontal plane.

[0083] Specifically, in S102, the number of faces N of the multi-faceted prism needs to be selected according to k = α / (360 / N), where k is a positive integer; among them, 360 / N is the central angle corresponding to a single reflecting surface of the multi-faceted prism. In order to match the correction of the reflecting surface of the multi-faceted prism by the optoelectronic autocollimator, the rotation of the multi-faceted prism takes the central angle corresponding to a single reflecting surface as the basic unit of rotation; in the case where it is less than one basic unit (k is not an integer), the value of N should be adjusted until k is a positive integer, the number of reflecting surfaces of the multi-faceted prism is determined, and a suitable multi-faceted prism is obtained.

[0084] Specifically, in S102, the multi-faceted prism rotates by α degrees. Based on the central angle corresponding to the reflecting surface of the multi-faceted prism, the multi-faceted prism is approximately rotated by α degrees, and the rotation angle of the multi-faceted prism is corrected through an optoelectronic autocollimator.

[0085] Specifically, it includes the following steps:

[0086] S1021: Set the optoelectronic autocollimator parallel to the plane where the x'-axis and z'-axis of the coordinate axis are located; select the position of the multi-faceted prism before it rotates by α degrees as the initial position, adjust the included angle of the optoelectronic autocollimator relative to the x'-axis so that the indication of the optoelectronic autocollimator on any reflecting surface of the multi-faceted prism is 0, and fix the optoelectronic autocollimator;

[0087] S1022: Rotate the polyhedron by k reflective surfaces, fine-tune the rotation angle of the polyhedron so that the photoelectric autocollimator reading is 0, and fix the polyhedron to complete the calibration; wherein k satisfies: k=α×N / 360, k is a positive integer, and N is the number of reflective surfaces of the polyhedron.

[0088] It should be noted that when the reading of the photoelectric autocollimator in S1022 is 0, the direction of the emitted light from the photoelectric autocollimator and the reflection surface of the polyhedron after rotating k reflection surfaces from the initial position are strictly perpendicular, with an accuracy greater than 0.08", which has higher positioning accuracy than the angle scale of the horizontal rotary table.

[0089] In the prior art, the positioning of the built-in parallel plane of the target hollow part is based on the rotation angle scale of the vertical rotary table on the processing machine tool, and thus the positioning accuracy of the built-in parallel plane of the target hollow part is affected by the rotation angle accuracy of the vertical rotary table; compared with the prior art: on the one hand, the present invention sets a positioning block parallel to the radial projection of the built-in axial parallel plane to be processed, and utilizes the parallel transfer law to convert the angular relationship of the built-in parallel plane of the target hollow part on the radial plane projection into the angular relationship between the positioning blocks; further, the present invention utilizes a photoelectric autocollimator to correct the angular relationship between the positioning blocks, which improves the accuracy compared to the angle scale of the vertical rotary table, and realizes the precise positioning of the built-in parallel plane of the target hollow part.

[0090] During implementation, the side of the bottom fixing member 3 in step 2 away from the pull rod 2 is fixedly connected to the vertical rotary table, thereby realizing the rotation of the preformed hollow part blank along the axis, adjusting the positioning block to horizontal, thereby realizing the alignment of the built-in parallel plane of the target hollow part corresponding to the positioning block.

[0091] Furthermore, in order to improve the accuracy of the positioning block timing, step 2 includes using a dial indicator to calibrate the positioning block position, which specifically includes the following steps:

[0092] S201: adjusting the rotation angle of the horizontal rotary table to which the positioning block is fixedly connected, and setting the positioning block approximately horizontally;

[0093] S202: A dial indicator is mounted on the machine tool spindle, and the machine tool spindle is moved along the projection line of the x'-axis on the horizontal plane, and the angle of the positioning block is fine-tuned according to the number indicated by the percentage pointer, until the dial indicator pointer reading changes below a threshold when the dial indicator needle slides from one end to the other end on the positioning block, and the positioning block is determined to be strictly horizontal.

[0094] It should be noted that in S201, the positioning block can be set approximately horizontally by visual judgment or by measuring the angle with an angle gauge. However, the positioning accuracy of the positioning block set by these two methods cannot meet the requirements of precision machining. Therefore, it is necessary to further correct the vertical relationship of the positioning block relative to the z-axis.

[0095] During implementation, the displacement probe of the dial indicator is used to measure the relative displacement of the side to be measured with respect to the dial indicator. By mounting the dial indicator on the machine tool spindle, it can be moved parallel to the x'-axis along the radial plane, and the displacement probe of the dial indicator contacts one of the sides to be measured (the top or bottom side) of the positioning block. If the side to be measured is not parallel to the projection line, there will be a displacement change of the displacement probe on the side to be measured, resulting in a change in the reading of the dial indicator. If the side to be measured is parallel to the projection line, no change or a zero change in the reading of the dial indicator can be detected.

[0096] Specifically, the change in the reading of the dial indicator pointer is introduced to evaluate the horizontal degree of the positioning block: if η is less than 1%, it is determined that the alignment is completed; the change in the reading η satisfies: η = S max -S min , where S max is the maximum value of the reading of the dial indicator pointer, and S min is the minimum value of the reading of the dial indicator pointer.

[0097] Preferably, the ratio of the length of the positioning block to its width or height is greater than 2. Increasing the ratio of the length of the positioning block to its width or height is beneficial to obtaining a larger height difference at both ends of the top of the positioning block, enabling the dial indicator to have a larger change in reading and obtaining a more sensitive signal.

[0098] Compared with the prior art, the present invention realizes the alignment of the internal parallel plane of the target hollow part by setting a positioning block parallel to the internal parallel plane of the target hollow part, and avoids the limitation of the angle scale accuracy of the vertical rotary table on the positioning accuracy of the internal parallel plane of the target hollow part. Further, the present invention corrects the position accuracy of the positioning block in the state to be aligned by using a dial indicator, greatly improving the positioning accuracy compared with the prior art, from 0.01° to 0.08″.

[0099] Optionally, the machining program in step 3 can be generated by programming software based on the three-dimensional models of the preformed hollow part blank and the machined part finished product.

[0100] Specifically, the machine tool machining is based on the x, y, z three-axis space coordinate system set by itself, where the x-axis is set parallel to the horizontal plane, the z-axis is set parallel to the axial direction of the machined part, and the y-axis is set perpendicular to the horizontal plane; the machine tool machining performs cutting processing on each point in the F(x, y, z) machining area within the preformed hollow part blank that has completed the alignment operation of the internal plane to be machined.

[0101] During implementation, the machining range of the machining tool 8 is restricted to a fixed area on one side of the center relative to the preformed hollow part blank through program control; correspondingly, the rotation angle of the vertical rotary table 5 is adjusted to machine different areas of the hollow part 4.

[0102] It should be noted that the control program of the machine tool does not include an identification module for the position of the preformed hollow part blank. Therefore, before machining the corresponding built-in plane to be machined on the hollow part 4, it is necessary to align the built-in plane to be machined on the preformed hollow part blank.

[0103] Specifically, step 3 of machining parts using the machine tool includes the following steps:

[0104] S301: Construct a three-dimensional model of the preformed hollow part blank and a three-dimensional model of the finished machined part in the machine tool control system;

[0105] S302: Generate a machining program by the machine tool control system based on the three-dimensional model of the preformed hollow part blank and the three-dimensional model of the finished machined part;

[0106] S303: Machine the aligned part based on the machining program to obtain a finished part with corresponding built-in parallel planes.

[0107] Specifically, in S301, a three-dimensional model of the preformed hollow part blank and a three-dimensional model of the finished machined part are constructed using the x, y, z three-axis spatial coordinate system set by the machine tool itself, where the x-axis is set parallel to the horizontal plane, the y-axis is set parallel to the axial direction of the machined part, and the z-axis is set perpendicular to the horizontal plane; in S302, the machine tool control system compares the three-dimensional model of the preformed hollow part blank and the three-dimensional model of the finished machined part to confirm the machining area F(x, y, z) and generate a machining program.

[0108] In this field, for part machining, it is often machined in two or more times: on the one hand, to prevent local overheating during long-term machining, tool and material expansion and deformation, and reference position drift, which affect machining accuracy; on the other hand, different machining accuracies have different requirements for tools, and finish machining causes greater tool wear, reducing the service life of the tool.

[0109] Preferably, between step 1 and step 2, there is also a pre-machining process for the preformed hollow part blank to further improve the above technical problems, including the following steps:

[0110] S104: Set up a reference line and obtain the included angle α0 between the reference line and the first positioning block; specifically, select a group of first positioning through holes 105 that are centrosymmetric, use the center connection line of the two as the reference line of the first positioning block, and obtain the included angle α0 between the reference line and the first positioning block;

[0111] S105: Fix the preformed hollow part blank to the rotary table through the processing die, and obtain the inclination angle α between the reference line and the horizontal plane. - , based on the included angle α0 and the angle α - Obtain the rotation angle α of the rotary table required for aligning the first positioning block. t1 ; Based on α t1 Complete the preliminary alignment of the first built-in parallel plane; specifically, α t1 satisfies: α t1 = α - + 90° - α0;

[0112] S106: Perform machining on the machining die to be processed that has completed the preliminary alignment of the first built-in parallel plane with a machining allowance of 0.2 mm to 0.6 mm.

[0113] S107: Based on α t1 and the included angle α1 between the first target plane and the second target plane, obtain the rotation angle α of the rotary table required for aligning the second positioning block. t2 , based on α t1 and the included angle α2 between the first built-in parallel plane and the third built-in parallel plane, obtain the rotation angle α of the rotary table required for aligning the third positioning block. t3 , …, based on α t and the included angle α between the Nth built-in parallel plane and the first built-in parallel plane. N Obtain the rotation angle α of the rotary table required for aligning the Nth positioning block. tN ; Specifically, the rotation angle α of the rotary table required for aligning the Nth positioning block. tN satisfies: α tN = α t1 + α N ; Based on α t2 , …, α tN Complete the preliminary alignment of the second built-in parallel plane, …, the Nth built-in parallel plane; perform machining on the preformed hollow part blank that has completed the preliminary alignment of the second built-in parallel plane, …, the Nth built-in parallel plane with a machining allowance of 0.2 mm to 0.6 mm.

[0114] Preferably, in order to ensure the positioning accuracy, obtain the included angle α0 between the reference line and the first positioning block through an optoelectronic autocollimator.

[0115] In the present invention, a preprocessing process is provided for the built-in parallel plane of the target hollow part before precision machining, which can remove the designed raw material allowance in the preformed hollow part blank, reduce the tool burden during precision machining, avoid problems such as tool overheating and raw material aging caused by too long precision machining time, and help improve the machining accuracy and extend the tool service life.

[0116] Compared with the prior art, the present invention uses the angle scale of the rotary table in the pre-machining process, which can achieve alignment more quickly while meeting the machining accuracy, thereby improving the machining efficiency.

[0117] Specifically, S106-S107 utilizes the above-mentioned machine tool to process parts, and the tool in S106, S107 and step 3 is a carbide tool that meets the following requirements: diameter 12mm-20mm, chamfer radius 1mm-3mm, and tool speed 800r / min-1500r / min.

[0118] Specifically, the hollow parts can be made of one or more of carbon steel, stainless steel, titanium alloy, aluminum alloy, and aluminum-magnesium alloy.

[0119] Preferably, a heat treatment process of the preformed hollow part blank is also included between the pre-processing process and step 2 to further reduce the residual stress of the pre-processing process, and the following steps are performed in sequence:

[0120] S108: heat treatment at 120±10℃ for 2h~6h, then air cooling to room temperature;

[0121] S109: Treat at -50±5℃ for 1h~3h, then let it warm up at room temperature;

[0122] S110: Heat treatment at 120±10℃ for 2h~6h, then air cool or cool in the furnace to room temperature.

[0123] The thermal stress continuously generated in the process of positive temperature-negative temperature-positive temperature is superimposed on the original residual stress, exceeding the yield strength of the material and causing plastic deformation, thereby reducing the original residual stress and further improving the plasticity and machinability of the cylindrical material.

[0124] On the other hand, the present invention discloses a processing mold for a hollow part, such as Figure 1 As shown: it includes an external pressing plate 1, a pull rod 2 and a bottom fixing piece 3, the external pressing plate 1 is located at one end of the pull rod, the bottom fixing piece 3 is located at the other end of the pull rod 2, the external pressing plate 1 and the bottom fixing piece 3 are fixedly connected by the pull rod 2, and a fixing area for clamping and fixing the preformed hollow part blank is provided between the external pressing plate 1 and the bottom fixing piece 3; the external pressing plate 1 is provided with a positioning block 101 parallel to the built-in axial parallel plane of the preformed hollow part blank at one end (i.e., the outer end face) away from the bottom fixing piece 3, and a center hole 102 for the entry and exit of the processing tool 8 is provided in the center of the external pressing plate 1, and the positioning block 101 is arranged in a solid area 103 on the outer peripheral edge of the center hole 102.

[0125] Specifically, Figure 2 As shown, the molded hollow part 4 is a hollow part whose inner side wall is provided with a built-in parallel plane 402 parallel to the axial direction. Figure 3Cross-sectional view of the formed hollow part 4 in the radial section (plane A-A) passing through the center of the built-in parallel planes 402 parallel to the axis: The multiple axially parallel built-in parallel planes 402 are not parallel to each other. Figure 4 Cross-sectional view of the raw blank of the hollow part 4 in the radial section (plane A-A): The raw blank of the hollow part 4 is a cylindrically symmetric part centered on the axis.

[0126] As Figure 1 shown: The inner wall of the hollow part 4 is provided with a first built-in parallel plane 4021 and a second built-in parallel plane 4022; the first built-in parallel plane 4021 and the second built-in parallel plane 4022 are not parallel to each other.

[0127] On the outer end face of the external pressure plate 1 of the processing die for the above-mentioned hollow part, a first positioning block 1011 and a second positioning block 1012 are provided; the first positioning block 1011 is parallel to the first built-in parallel plane 4021, and the second positioning block 1012 is parallel to the second built-in parallel plane 4022.

[0128] There is one or more positioning blocks 101, which correspond one-to-one to the built-in parallel planes 402' of the target hollow part.

[0129] Figure 5 Shown is the state where the first built-in parallel plane 4021 and the second built-in parallel plane 4022 are not yet machined: On the side wall of the preformed hollow part blank, there are a first target plane 4021' and a second target plane 4022'; the first target plane 4021' at the dashed line is obtained by machining to obtain Figure 1 the first built-in parallel plane 4021 in Figure 1 the second built-in parallel plane 4022; the first positioning block 1011 is parallel to the first target plane 4021', and the second positioning block 1012 is parallel to the second target plane 4022'; through parallel transfer, the included angle between the first built-in parallel plane 4021 and the second built-in parallel plane 4022 is the same as the included angle between the first target plane 4021' and the second target plane 4022'.

[0130] Specifically, as Figure 5 shown, since the built-in parallel planes 402' of the target hollow part are axially parallel, their projections on the end face along the axis are straight line segments; the positioning block 101 is set to be parallel to the projection of the built-in parallel plane 402' of the target hollow part on the end face along the axis.

[0131] During implementation, the positioning block 101 is set to be strip-shaped and fixed to the outer end face of the external pressing plate 1; the radial cross-section of the positioning block is set to be circular or quadrilateral; according to the principle of parallel transmission, by measuring the horizontal state of the positioning block 101, it is more convenient and accurate to judge the horizontal state of the built-in parallel plane of the target hollow part corresponding to the positioning block 101; moreover, since the tool is perpendicular to the horizontal plane, by adjusting the positioning block 101 to be horizontal, the alignment of the built-in parallel plane of the corresponding target hollow part can be achieved.

[0132] Compared with the prior art, in the present invention, by setting a positioning block parallel to the radial projection of the built-in parallel plane of the target hollow part, the inclination angle of the built-in parallel plane of the target hollow part relative to the horizontal plane is converted into the included angle between the positioning block and the horizontal plane. Among them, the built-in parallel plane of the target hollow part is abstract and invisible before the processing is completed, while the positioning block is specifically visible. The advantage of doing this is that: the positioning block can be measured and corrected before processing the built-in parallel plane, so as to realize the correction of the built-in parallel plane of the target hollow part and improve the processing accuracy.

[0133] Furthermore, the positioning block 101 is fixed to the body of the external pressing plate 1; the ratio of the length of the positioning block to its width or height is greater than 2; when detecting the horizontal state of the positioning block 101, using the relatively large ratio of the length of the positioning block to its width or height is beneficial to obtaining more sensitive signals at both ends of the top of the positioning block, which is beneficial to further improving the alignment accuracy of the built-in parallel plane corresponding to the positioning block 101.

[0134] Specifically, multiple positioning blocks are corrected for the angular relationship between their radial projections by an optoelectronic autocollimator, and the rotary table corrects and positions the multiple positioning blocks 101; specifically, the external pressing plate 1 is fixed to the rotary table, and based on the included angle of the radial projection of the built-in parallel plane of the target hollow part, the rotary table is rotated to determine the installation position of the positioning block.

[0135] For the case of machining multiple axially parallel built-in parallel planes, multiple positioning blocks 101 corresponding one-to-one parallel to the projections of the built-in parallel planes in the radial plane need to be provided on the external pressing plate 1; according to the principle of parallel transmission, the included angle between the projections of any two axially parallel built-in parallel planes in the radial plane is the same as the included angle between the corresponding positioning blocks 101 in the radial plane.

[0136] During implementation, the first positioning block 101 is set as the reference positioning block, and the remaining positioning blocks are set according to the angle with the reference positioning block. It should be noted that the positioning blocks can be set on multiple parallel lines that satisfy the angular relationship with the reference positioning block. At the same time, there are multiple feasible installation positions for the positioning blocks to translate on the same parallel line. Therefore, an installation position where the positioning blocks can be set without obstruction needs to be selected on the outer side of the outer pressing plate 1. The positioning blocks set at this installation position should not obstruct the setting of the remaining structures and functions on the same side of the outer pressing plate 1. Based on this, the included angle between any two positioning blocks set on the outer pressing plate 1 is the same as the included angle between the corresponding axially parallel built-in parallel planes projected onto the radial plane; the angular relationship of the positioning blocks set by the above method corresponds to the included angle of the axially parallel built-in parallel planes to be machined projected onto the radial plane. Based on the axially parallel built-in parallel planes obtained after alignment using the above positioning blocks, the angular relationship of their projections onto the radial plane is consistent with the design expectation.

[0137] Specifically, as Figure 1 shown: The machining tool can freely enter and exit the central hole 102, so it can meet the machining of the interior of the preformed hollow part blank; the outer side of the edge solid region 103 is used to fix the positioning block 1, and the inner side is press-fitted and connected to the hollow part 4.

[0138] Furthermore, in order to realize the firm connection between the bottom fixing part 3 and the outer pressing plate 1, the processing mold is provided with a movable connection structure for adjusting the pressing degree of the outer pressing plate 1 and the bottom fixing part 3 on the hollow part 4, such as Figure 1 shown, the movable connection structure includes: a pull rod mounting hole 104 provided at the edge of the body of the outer pressing plate 1; a pull rod 2 with a thread at one end and fixedly connected to the bottom fixing part 3 at the other end, and a nut matching the thread; and it is press-fitted and connected to the edge solid region 103 through the nut. The thread setting enables the pull rod 2 to adjust the tightening degree of the bottom fixing part 3 and the outer pressing plate 1, and adjust the end surface pressing strength of the preformed hollow part blank.

[0139] Preferably, the pull rod mounting holes 104 are symmetrically arranged about the center of the outer pressing plate 1, and the pull rods 2 corresponding to the number of pull rod mounting holes 104 pass through the pull rod mounting holes 104 and are fixedly connected to the edge solid region 103, applying force evenly in all directions relative to the centers of the edge solid region 103 and the bottom fixing part 3.

[0140] At the same time, in order to further improve the fastening degree between the preformed hollow part blank and the mold and prevent relative sliding, as Figure 3 shown, the edge solid region 103 is provided with a plurality of first positioning through holes 105; as Figure 4As shown in the figure, a second positioning hole 401 is provided on one side of the preformed hollow part blank connected to the external pressing plate 1; one end of the first positioning through hole 105 is axially movably connected to the preformed hollow part blank; the preformed hollow part blank can be radially rotationally locked by mating connection with the first positioning through hole 105 and the second positioning hole 401 through a positioning pin 106, preventing relative radial sliding and ensuring stability and precision during processing.

[0141] Specifically, the second positioning hole 401 is a concave hole with one end open, and the positioning pin 106 passes through the first positioning through hole 105 and is fixed in the second positioning hole 401.

[0142] On the other hand, the present invention discloses a processing device for hollow parts, which further includes, in addition to the above-mentioned processing die: a vertical rotary table 5, the vertical rotary table 5 is fixedly connected to the other end of the bottom fixing member 3 facing away from the external pressing plate 1, and the vertical rotary table 5 is movably connected to one side of the machine tool platform 6; the other side of the machine tool platform 6 is movably connected to a machine tool spindle 7, and the end of the machine tool spindle 7 close to the external pressing plate 1 is connected with a processing tool 8.

[0143] During implementation, the processing range of the processing tool 8 is limited to a fixed area on one side of the center of the preformed hollow part blank through program control; correspondingly, the rotation angle of the vertical rotary table 5 is adjusted so that different areas of the preformed hollow part blank enter the fixed area where the processing tool 8 is located during processing, realizing the processing of different areas of the preformed hollow part blank.

[0144] It should be noted that the control program of the machine tool does not include an identification module for identifying the position of the preformed hollow part blank. Therefore, before obtaining the corresponding target hollow part by processing the preformed hollow part blank, it is necessary to complete the alignment of the built-in plane to be processed of the preformed hollow part blank.

[0145] Compared with the prior art, the present invention completes the transmission of the angular relationship of the radial projection of the built-in parallel plane of the target hollow part to the angular relationship of the corresponding positioning block by setting a positioning block parallel to the radial projection of the built-in parallel plane of the target hollow part. Therefore, the processing of the built-in parallel plane of the target hollow part can be decomposed into two parts: the alignment and positioning of the built-in parallel plane of the target hollow part and the processing of the built-in parallel plane of the target hollow part; thus, when designing the processing program of the present invention, it is not necessary to add a positioning function module. Compared with the prior art where the workpiece to be processed is fixed and only the cutting method of the processing tool is used, the complexity of the program design and the stroke of the processing tool are reduced, and the processing precision and reliability are improved.

[0146] In order to illustrate the technical progress of the present invention, the following embodiments are further disclosed:

[0147] Embodiment 1

[0148] This embodiment discloses a processing method for a hollow part, as Figure 7 shown, including the following steps:

[0149] Step 1: Set positioning blocks parallel to the built-in parallel planes of the target hollow parts on the outer side of the feed end of the processing die;

[0150] Specifically, one end of the processing die is fixedly connected to the vertical rotary table, and the other end is the feed end. Determine the angle between the positioning blocks corresponding to the built-in parallel planes of the two target hollow parts according to the angle of the radial projection of the built-in parallel planes of the two target hollow parts, and sequentially set each positioning block according to the angle of the positioning blocks;

[0151] Step 2: Based on the positioning blocks, complete the alignment of the preformed hollow part blank fixed on the vertical rotary table with the built-in parallel planes of the target hollow parts corresponding to the positioning blocks.

[0152] Step 3: Process the aligned preformed hollow part blank to obtain the built-in parallel planes.

[0153] Specifically, setting the positioning blocks parallel to the built-in parallel planes of the target hollow parts in Step 1 includes the following steps:

[0154] S101: Coaxially fix the external pressing plate 1 to the horizontal rotary table with a group of first positioning through holes 105 that are centrosymmetric with respect to the geometric center of the external pressing plate 1; take the geometric center of the outer side surface of the feed end of the processing die as the origin, take the center connection line of the first positioning through holes 105 in the initial position as the x'-axis, establish the coordinate axis z'-axis in the plane of the horizontal rotary table in the initial position perpendicular to the x'-axis direction, and take the perpendicular line passing through the origin and perpendicular to the coordinate axes x' and z' as the y'-axis; a first positioning block 1011 is arranged in the vertical z'-axis direction in the solid area outside the external pressing plate 1;

[0155] S102: Obtain the angle between the first positioning block 1011 and the second positioning block 1012 as 60°; a multi-faceted prism is fixedly arranged in the central area of the horizontal rotary table surface; rotate the multi-faceted prism by 60°, and arrange a second positioning block 1012 in the vertical z'-axis direction in the solid area outside the external pressing plate 1;

[0156] S103: Based on the angle between the first positioning block and the third positioning block (90°) and the angle between the first positioning block and the fourth positioning block (120°), sequentially set the third positioning block and the fourth positioning block according to the method of S102.

[0157] Furthermore, to improve the positioning accuracy of the positioning blocks on the external pressing plate 1, it is necessary to correct the positional relationship of the first positioning block 1011, the second positioning block 1012, the third positioning block 1013, and the fourth positioning block 1014 relative to the z'-axis, including the following steps:

[0158] S1011: Set the positioning block perpendicular to the z'-axis direction by visual judgment.

[0159] S1012: By mounting a dial indicator on the machine tool spindle, parallel movement along the x'-axis of the dial indicator coordinate axis can be achieved. The displacement probe of the dial indicator contacts a side to be measured of the positioning block. Calculate the change in the reading of the dial indicator pointer, and adjust the angle of the positioning block until η is less than 1%, then it is judged that the alignment is completed.

[0160] Furthermore, to improve the positioning accuracy of the positioning block on the external pressing plate 1, it is necessary to correct the rotation accuracy when the multi-faceted prism rotates by α degrees in S102, including the following steps:

[0161] S1021: Set the photo-electric auto-collimator parallel to the plane where the x'-axis and z'-axis are located. Select the initial position when the first positioning block 1011 in S101 is set perpendicular to the z'-axis direction, and adjust the angle of the photo-electric auto-collimator relative to the x'-axis so that the reading of the photo-electric auto-collimator on any reflecting surface of the multi-faceted prism is 0, and then fix the photo-electric auto-collimator.

[0162] S1022: For the second positioning block 1012, the number of reflecting surfaces N of the multi-faceted prism satisfies N = k×360 / α = 6k, where k is a positive integer. Therefore, considering the processing difficulty and cost of the multi-faceted prism, a six-sided prism, a twelve-sided prism, or an eighteen-sided prism can be selected. Rotate the multi-faceted prism by k reflecting surfaces (the corresponding k values for the six-sided prism, twelve-sided prism, and eighteen-sided prism are 1, 2, and 3), finely adjust the rotation angle of the multi-faceted prism so that the reading of the photo-electric auto-collimator is 0, and fix the rotation angle of the multi-faceted prism to complete the correction of the second positioning block. Use the same method to complete the correction of the third positioning block and the fourth positioning block.

[0163] Furthermore, to improve the accuracy of the positioning block during alignment, step 2 includes using a dial indicator to correct the position accuracy of the positioning block, specifically including the following steps:

[0164] S201: Adjust the rotation angle of the horizontal rotary table, and set the positioning block approximately horizontally by visual judgment.

[0165] S202: Mount a dial indicator on the machine tool spindle and move the spindle left and right along the projection line of the radial plane of the preformed hollow part blank in the horizontal plane, and finely adjust the angle of the positioning block according to the reading of the dial indicator until the change η in the reading of the dial indicator pointer is less than 1% when the dial indicator needle slides from one end to the other end on the positioning block, and it is determined that the positioning block is strictly horizontal.

[0166] The ratio of the length of the positioning block to its width or height is set to 5, and the width and height are the same. Increasing the ratio of the length of the positioning block to its width or height is beneficial to obtaining a larger height difference at both ends of the top of the positioning block, enabling the dial indicator to have a larger reading change and obtaining a more sensitive signal.

[0167] There is also a pre - processing process for the pre - formed hollow part blank between Step 1 and Step 2;

[0168] Specifically, the pre - processing process for the pre - formed hollow part blank includes the following steps:

[0169] S104: Select a set of first positioning through - holes 105 that are centrosymmetric, take the center - connecting line of the two as the reference line of the first positioning block, and obtain the included angle α0 between the reference line and the first positioning block;

[0170] S105: Fix the pre - formed hollow part blank on the rotary worktable through a processing die, and obtain the inclination angle α of the reference line with respect to the horizontal plane. - , based on the included angle α0 and the angle α - Obtain the rotation angle α of the rotary worktable required for aligning the first positioning block; t1 ; Based on α t1 Complete the preliminary alignment of the first built - in parallel plane; specifically, α t1 Satisfies: α t1 =α - +90° - α0;

[0171] S106: Machine the processing die that has completed the preliminary alignment of the first built - in parallel plane with a 0.2 - mm allowance left;

[0172] S107: Based on α t1 and the included angle α1 between the first target plane and the second target plane, obtain the rotation angle α of the rotary worktable required for aligning the second positioning block; t2 , based on α t1 and the included angle α2 between the first built - in parallel plane and the third built - in parallel plane, obtain the rotation angle α of the rotary worktable required for aligning the third positioning block; t3 , …, based on α t and the included angle α between the Nth built - in parallel plane and the first built - in parallel plane N Obtain the rotation angle α of the rotary worktable required for aligning the Nth positioning block; tN Specifically, the rotation angle α of the rotary worktable required for aligning the Nth positioning block tN , satisfies: α tN =α t1 +α N ; Based on α t2 , …, α tN Complete the preliminary alignment of the second built - in parallel plane, …, the Nth built - in parallel plane; Machine the pre - formed hollow part blank that has completed the preliminary alignment of the second built - in parallel plane, …, the Nth built - in parallel plane with a 0.2 - mm allowance left.

[0173] Preferably, in order to ensure positioning accuracy, the angle α0 between the reference line and the first positioning block is obtained by a photoelectric autocollimator.

[0174] This embodiment sets up a pre-machining process and performs pre-machining under the premise of meeting the accuracy requirements, thereby improving the problems of reference drift, tool overheating and raw material aging and deformation caused by too long finishing time, which helps to improve machining accuracy and extend tool life.

[0175] The present invention provides a pre-machining process for the built-in parallel plane of the target hollow part before fine machining, which can remove the raw material surplus designed in the preformed hollow part blank, reduce the burden of the tool during precise machining, avoid tool overheating and raw material aging problems caused by too long fine machining time, and help improve machining accuracy and extend tool life.

[0176] Compared with the prior art, the present invention uses the angle scale of the rotary table in the pre-machining process, which can achieve alignment more quickly while meeting the machining accuracy, thereby improving the machining efficiency.

[0177] Specifically, the tool used for processing in S106 and step 3 is a carbide tool that meets the following requirements: diameter 16 mm, chamfer radius 2 mm, and tool speed 1000 r / min.

[0178] Specifically, the hollow part is made of titanium alloy.

[0179] Preferably, a heat treatment process of the preformed hollow part blank is also included between the pre-processing process and step 2 to further reduce the residual stress of the pre-processing process, and the following steps are performed in sequence:

[0180] S108: heat treatment at 120°C for 6 hours, followed by air cooling to room temperature;

[0181] S109: Treat at -50°C for 2 h, then allow to warm up at room temperature;

[0182] S110: Heat treatment at 120℃ for 6h, then air cooling or furnace cooling to room temperature.

[0183] Specifically, step 3 and S106-S107 use a machine tool to process parts, including the following steps:

[0184] S301: Using the x, y, and z three-axis spatial coordinate system set by the machine tool itself, wherein the x-axis is set parallel to the horizontal plane, the y-axis is set parallel to the axial direction of the processed part, and the z-axis is set perpendicular to the horizontal plane, a three-dimensional model of the preformed hollow part blank and a three-dimensional model of the processed part finished product are constructed;

[0185] S302: The machine tool control system compares the three-dimensional model of the preformed hollow part blank with the three-dimensional model of the finished part to obtain the area to be processed F (x, y, z), and generates a processing program;

[0186] S303: Process the aligned part from the inside to the outside based on the machining program to obtain a finished part with corresponding built-in parallel planes.

[0187] Embodiment 2

[0188] This embodiment discloses a positioning method for the built-in axial parallel planes of a hollow part. As Figure 8 shown, it includes steps 1 to 2 of Embodiment 1 and all steps and specific implementation manners of S101 - S110, S1011 - S1012, S1021 - S1022, S201 - S202. In this embodiment, by setting positioning blocks parallel to the built-in parallel planes of the target hollow part, the angular relationship of the projection of the built-in parallel planes of the target hollow part in the radial plane is converted into the angular relationship between the positioning blocks, realizing the positioning of the relative position relationship between the built-in parallel planes of the target hollow part. At the same time, the inclination angle of the built-in parallel planes of the target hollow part relative to the horizontal plane is converted into the included angle between the positioning blocks and the horizontal plane, and the alignment of the built-in parallel planes of the target hollow part is achieved by confirming the position accuracy of the positioning blocks, thereby realizing the positioning of the absolute position relationship between the built-in parallel planes of the target hollow part relative to the horizontal plane.

[0189] Embodiment 3

[0190] This embodiment discloses a processing mold for a hollow part, which is used for the above-mentioned processing method. As Figure 1 shown: An external pressing plate 1 is provided at one axial end of the processing mold, and a bottom fixing member 3 is provided at the other end; a fixing area for clamping and fixing the hollow part 4 is provided between the external pressing plate 1 and the bottom fixing member 3 and is fixedly connected by a pull rod 2; a positioning block 101 parallel to the built-in parallel planes of the target hollow part is provided on the side of the external pressing plate 1 away from the bottom fixing member 3.

[0191] Figure 2 Shows a 45° top-down view of the formed hollow part 4; Figure 3 Shows a cross-sectional view of the radial section (A - A plane) where the centers of the axially parallel built-in parallel planes 402 are located; As Figure 2 And Figure 3 shown: Multiple axially parallel built-in parallel planes 402 are not parallel to each other. Figure 4 Shows a cross-sectional view of the raw material blank of the hollow part 4 in the radial section (A - A plane), as Figure 3 And Figure 4 shown: The hollow part 4 is obtained by machining the part body 403 from the inside to the outside.

[0192] As Figure 5As shown in the figure: The positioning block 101 is a cuboid, which is fixed to the external pressing plate 1 through the axial side surface. By measuring the horizontal state of the positioning block 101, it is more convenient and accurate to judge the horizontal state of the built-in parallel plane of the target hollow part corresponding to the positioning block 101. By adjusting the positioning block 101 to be horizontal, the alignment of the built-in parallel plane of the corresponding target hollow part is realized. At the same time, the positioning block can be measured and corrected before machining the built-in parallel plane, so as to correct the built-in parallel plane of the target hollow part and improve the machining accuracy.

[0193] As Figure 5 shown in the figure: There are four positioning blocks 101, with the same size. The ratio of the length to the width or height of the positioning block is 5. The larger ratio of the length to the width or height is beneficial to obtaining more sensitive signals at both ends of the top of the positioning block, which is beneficial to further improving the alignment accuracy of the built-in parallel plane corresponding to the positioning block.

[0194] At the same time, the angular relationship between the radial projections of multiple positioning blocks is corrected by an optoelectronic autocollimator, and multiple positioning blocks 101 are corrected and positioned on the external pressing plate 1 through a rotary table. For multiple axially parallel built-in parallel planes to be machined, positioning blocks 101 corresponding to the projections of the built-in parallel planes parallel to the radial plane need to be set on the external pressing plate 1. According to the principle of parallel transmission, the included angle between the projections of any two built-in parallel planes in the radial plane is the same as the included angle between the corresponding positioning blocks 101.

[0195] As Figure 1 shown in the figure, the external pressing plate 1 is provided with an edge solid area 103 on the outer periphery of the central hole 102, and the edge solid area 103 is provided with pull rod mounting holes 104 that are centrosymmetric with respect to the center of the external pressing plate 1. At the same time, the pull rod 2 is provided with threads, and is press-fitted and connected to the edge solid area 103 through nuts to realize the fastening connection of the bottom fixing part 3 and the external pressing plate 1. Multiple pull rods 2 are fixedly connected to the edge solid area 103 through the pull rod mounting holes 104, and force is applied evenly in all directions relative to the centers of the edge solid area 103 and the bottom fixing part 3.

[0196] As Figure 3 shown in the figure, the edge solid area 103 is provided with multiple first positioning through holes 105; as Figure 4 shown in the figure, the side of the hollow part 4 connected to the external pressing plate 1 is provided with a second positioning hole 401; the matching connection of the positioning pin 106 with the first positioning through hole 105 and the second positioning hole 401 can prevent relative radial sliding and ensure the stability and accuracy during machining.

[0197] The second positioning hole 401 is a concave hole with one end open, and the positioning pin 106 passes through the first positioning through hole 105 and is fixed in the second positioning hole 401.

[0198] Embodiment 4

[0199] This embodiment discloses a processing device for a hollow part, including the processing die described in Embodiment 3, which is used for the above-mentioned processing method. For example, Figure 6 as shown, it further includes: a vertical rotary table 5, one end of the vertical rotary table 5 is fixedly connected to the other end of the bottom fixing member 3 facing away from the external pressing plate 1, and the other end of the vertical rotary table 5 is movably connected to one side of the machine tool platform 6; the other side of the machine tool platform 6 is movably connected to a machine tool spindle 7, and the end of the machine tool spindle 7 close to the external pressing plate 1 is connected to a processing tool 8.

[0200] During implementation, a central hole 102 for the entry and exit of the processing tool 8 is provided at the center of the external pressing plate 1; the processing range of the processing tool 8 is limited to a fixed area on one side of the center of the relative hollow part 4 through program control; correspondingly, the rotation angle of the vertical rotary table 5 is adjusted so that different areas of the hollow part 4 enter the fixed area where the processing tool 8 is located during processing, meeting the processing requirements of different areas of the hollow part 4.

[0201] It should be noted that the control program of the machine tool does not include an identification module for the position of the hollow part 4. Therefore, before processing the corresponding internal plane to be processed on the hollow part 4, the internal plane to be processed of the hollow part 4 needs to be aligned.

[0202] As an example, Figure 6 as shown, the processing range of the processing tool 8 is limited to the bottom area of the hollow part 4 through program control; the rotation angle of the rotary table 5 relative to the machine tool platform 6 is adjusted to make the first positioning block 1011 horizontal, realizing the alignment of the first target plane 4021', and at the same time, the first target plane 4021' is placed within the processing range 405 of the processing tool 8.

[0203] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A processing method for a hollow part with axially parallel planes inside, characterized in that, Including the following steps: A positioning block parallel to the built-in axial parallel plane of the target hollow part is arranged outside the feed end of the processing die; Pre-process the preformed hollow part blank: Establish a reference line and obtain the included angle α0 between the reference line and the first positioning block; Fix the preformed hollow part blank on the rotary table through the processing die to obtain the inclination angle α of the reference line with respect to the horizontal plane - , based on the included angle α0 and the angle α - Obtain the rotation angle α of the rotary table required for the alignment of the first positioning block t1 ; Based on α t1 Complete the preliminary alignment of the first built-in parallel plane; among them, α t1 Satisfies: α t1 =α - +90° - α0; Perform machining with a margin on the machining die that has completed the preliminary alignment of the first built-in parallel plane; Based on α t1 and the included angle α1 between the first target plane and the second target plane, obtain the rotation angle α of the rotary table required for aligning the second positioning block t2 ; based on α t1 and the included angle α2 between the first built-in axial parallel plane and the third axial parallel built-in parallel plane, obtain the rotation angle α of the rotary table required for aligning the third positioning block t3 , …, based on α t and the included angle α between the Nth built-in parallel plane and the first built-in axial parallel plane N obtain the rotation angle α of the rotary table required for aligning the Nth positioning block tN ; Based on the positioning block, complete the alignment of the built-in axial parallel plane of the preformed hollow part blank to the target hollow part; Machine the aligned preformed hollow part blank to obtain the built-in axial parallel plane; Setting a positioning block parallel to the built-in axial parallel plane of the target hollow part includes: confirming the included angle of the positioning block corresponding to the built-in axial parallel plane parallel to the two target hollow parts according to the included angle of the radial projection of the built-in axial parallel plane of the two target hollow parts, and sequentially setting each positioning block according to the included angle of the positioning block.

2. The processing method according to claim 1, characterized in that, The machining of the preformed hollow part blank includes: restricting the machining range of the machining tool to a fixed area on one side of the center of the preformed hollow part blank.

3. The processing method according to claim 2, characterized in that, Adjust the rotation angle of the vertical rotary table fixedly connected to the preformed hollow part blank to achieve machining of different regions of the preformed hollow part blank.

4. The processing method according to claim 1, wherein Setting a positioning block parallel to the built-in axial parallel plane of the target hollow part includes the following steps: Taking the geometric center of the outer side surface of the feed end of the processing die as the origin, taking the radial plane of the processing die as the x'z' plane, constructing an x'y'z' three-axis coordinate system, and setting a first positioning block as the reference positioning block in the x'z' plane; Obtain the included angle α between the first positioning block and the second positioning block. A multi-faceted prism is fixedly arranged in the central area of the horizontal rotary table; rotate the multi-faceted prism by α degrees, and set the second positioning block in the area in the x'z' plane, where the included angles of the second positioning block with the x' axis and the z' axis are the same as those of the first positioning block; Based on the included angle between the first positioning block and the Mth positioning block, rotate the multi-faceted prism by the included angle between the first positioning block and the Mth positioning block, and set the Mth positioning block; M is a positive integer greater than or equal to 3.

5. The processing method according to claim 1, characterized in that, Between the pre-processing process and the alignment of the built-in parallel plane, it also includes a heat treatment process for the preformed hollow part blank.

6. The processing method according to claim 5, characterized in that, The heat treatment of the preformed hollow part blank includes the following steps: At 120 ± 10 °C, heat treat for 2 h to 6 h, and then air cool to room temperature; At -50 ± 5 °C, process for 1 h to 3 h, and place it at room temperature to rise; At 120 ± 10 °C, heat treat for 2 h to 6 h, and then air cool or cool in the furnace to room temperature.

7. The processing method according to claim 1, wherein Obtain the machining program for the built-in parallel plane, which is generated by programming software based on the three-dimensional model of the preformed hollow part blank and the three-dimensional model of the machined part finished product.

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