Precision Machining Device For Sphere And Machining Method

Abstract

A precision machining device for a sphere and a machining method. The machining device comprises a cavity, an abrasive particle flow (10), and a circulation device; a workpiece (6) is placed in the cavity; the cavity is composed of two hollow hemispheres (7, 9); the two hemispheres (7, 9) are each provided with a main flow channel; the main flow channels are communicated with the cavity; one end of each of the main flow channels of the two hemispheres is connected to the circulation device; and the abrasive particle flow (10) is made to grind the workpiece (6) by means of the circulation device. The plurality of main flow channels are uniformly distributed in the hemispheres (7, 9), each main flow channel is provided with a plurality of branch flow channels communicated with the cavity, and the branch flow channels gradually shrink in the flow direction. According to the machining method, precise machining is achieved by means of different abrasive particle flow pressures on the surface of the workpiece, so that the shape precision of the workpiece can be effectively improved.

Description

The present disclosure relates to the field of special machining, and particularly to a sphere precision machining device and a machining method. BACKGROUND High-precision ball has high requirements on the shape accuracy, surface quality and consistency of the ball, which has a very critical impact on the production of high-end basic components such as high-precision linear guides, high-precision ball screws, high-performance bearings and high-precision optical devices. It will affect the overall accuracy of the precision components, and even cause damage to other components, ultimately affecting the service life of the overall equipment. SUMMARY In view of the deficiencies in the prior art, the present disclosure provides a sphere precision machining device and a machining method. By placing the workpiece in a sealed circular cavity and passing a stream of abrasive particles into the circular cavity. The circular cavity is equipped with a main flow channel for the circular flow of abrasive grain flow, the main flow channel is equipped with sub-branching channels, the abrasive grain flow is contacted with the workpiece through the sub-branching channels and the workpiece surface bumps are processed for precision grinding. The present disclosure achieves the above technical object by the following technical means. A sphere precision machining device comprising a cavity, an abrasive grain stream and a circulation device. The cavity holds the workpiece, the cavity comprising two hollow hemispheres. A main flow channel is provided in each of the two hemispheres, the main flow channel being in communication with the cavity. One end of the main flow path of each of the two hemispheres is connected to a circulating means by which a stream of abrasive grains is made to grind the workpiece. Further, a plurality of main flow channels are disposed homogeneously inside the hemisphere, each of the main flow channels being provided with a plurality of branch flow channels connected to the cavity, the branch flow channels tapering in a flow direction. Further, an axis of a branch runners is at an angle of 20° to 45° in the direction of the radius in which they are located. Further, a sealing assembly is provided between the mating surfaces of the two hemispheres for sealing. Further, control systems, vibration sensors and pressure sensors are also included, where a number of the vibration sensors are mounted on the inner wall of the cavity for detecting vibration signals generated by an abrasive grain flow, the pressure sensor is configured to detect the pressure of the abrasive grain flow output from the circulation device, the control system regulates the output pressure of the circulation device according to the vibration signal. A method of processing the sphere precision machining device as described, further including steps of: placing the workpiece into the cavity and install the hemisphere seal, pumping the abrasive stream into the cavity for grinding of the workpiece by means of a circulation device, detecting, by a number of vibration sensors, vibration signals generated by an abrasive grain flow, and regulating, by a control system, the output pressure of the circulation device according to the vibration signals, and after a grinding process is completed, taking out the workpiece to check whether the shape accuracy and surface quality meet the set requirements, if not, putting the workpiece back into the cavity for processing. Further, the control system regulates the output pressure of the circulation device in accordance with the vibration signal, specifically including: as an initial state, setting the output pressure of the circulation device to Po; after processing for a time ti, comparing, by the control system, the average value Sti of a number of vibration signals with a first set value according to the average value Su of the number of vibration signals, where when the average value Su is less than the first set value, completing the grinding processing; when the average value Sti is greater than the first set value, increasing, by the control system, the output pressure of the circulation device to Pi; after adjusting the pressure and processing for a time t2, when the average value S12 is greater than the first set value and the average value St2 is less than the average value St2, reducing, by the control system, the output pressure of the circulation device to P2, where Pi>P2>Po, until the average value Sti is less than the first set value. Beneficial effects of the present disclosure are: 1. The sphere precision machining device and the machining method described in the present disclosure achieve precision machining of a high-precision sphere by sealing two hemispheres. The axes of abrasive flow inlet hole and abrasive flow return hole are designed to make an angle of 20°-45° to the radius direction where they are located, so that the abrasive flow drives the workpiece to rotate in counterclockwise direction. Precision machining using the difference in abrasive flow pressure on the surface of the workpiece can effectively improve the shape accuracy of the workpiece. 2. The sphere precision machining device and the machining method described in the present disclosure use changes in vibration signals to detect the machining state of the workpiece. At the beginning of machining, due to the uneven surface of the workpiece, the pressure on the raised part of the workpiece is high, the cutting effect of the abrasive flow on the raised part is increased, and the vibration in the machining unit will be high. When all the projections on the workpiece are removed, the workpiece gradually turns into a precise sphere shape and the vibration inside the machining unit gradually decreases. The control system decides whether the machining of the workpiece is completed or not based on the judgement of the vibration signal. The use of this inspection method effectively reduces the number of actual measurements of the workpiece during machining and improves productivity. BRIEF DESCRIPTION OF THE DRAWINGS In order to illustrate more clearly the technical solutions in the embodiments or prior art of the present disclosure, the accompanying drawings, which are to be used in the description of the embodiments or prior art, will be briefly described below. The accompanying drawings in the following description are some embodiments of the present disclosure. It will be obvious to a person of ordinary skill in the art that other drawings can be obtained from these drawings without creative labour. FIG. 1 shows a sectional view of the sphere precision machining device described in the present disclosure. FIG. 2 shows an exploded view of the sphere precision machining device described in the present disclosure. FIG. 3 shows a flow chart of a processing method of the sphere precision machining device described in the present disclosure. In the figures: 1-bolt connector, 2-positioning pin, 3-serrated sealing structure, 4-abrasive grain flow inlet, 5- vibration sensor, 6-workpiece, 7-first hemisphere, 8-abrasive grain flow inlet hole, 9-second hemisphere, 10-abrasive stream, 11-abrasive stream return hole, 12-control system, 13-signal line, 14-pipe fitting thread, 15-connecting pipe, 16-sealing washer, 17-abrasive stream outlet, 18-pressure pump, 19-abrasive stream conveying pipe, 20-abrasive stream recycling device, 21-pressure valve, 22-workpiece protruding place, 23-workpiece flat place. DETAILED DESCRIPTION OF THE EMBODIMENTS The present disclosure is further described below in connection with the accompanying drawings and specific embodiments, but the scope of protection of the present disclosure is not limited thereto. Embodiments of the present disclosure are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar labels throughout indicate the same or similar elements or elements having the same or similar functions. The following embodiments described by reference to the accompanying drawings are exemplary and are intended for use in explaining the present disclosure and are not to be construed as a limitation of the invention. In the description of the present disclosure, it is to be understood that the terms "centre", "longitudinal", "transverse", "length", "width", "thickness", "top", "bottom", "axial", "radial", "vertical", "horizontal", "inner", "outer" and the like indicate orientation or positional relationships based on those shown in the accompanying drawings, and are only for the purpose of facilitating the description of the present disclosure and of simplifying the description and are not indicative of, or implied to indicate, that a device or element referred to must be of a particular orientation, be constructed and operated with a particular orientation and are not to be construed as limitations to the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with the terms "first", "second" may expressly or implicitly include one or more such features. In the description of the present disclosure, "more than one" means two or more, unless otherwise expressly and specifically limited. In the present disclosure, unless otherwise expressly provided and limited, the terms "mounted", "connected", "connected", "fixed", etc. are to be understood in a broad sense. "and the like are to be understood in a broad sense, for example, as a fixed connection, a detachable connection, or a connection in one piece; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present disclosure may be understood on a case-by-case basis. As shown in FIG. 1 and FIG. 2, the sphere precision machining device described in the present disclosure comprises a circular cavity, an abrasive grain stream 10 and a circulation device. The the circular cavity is configured to hold the workpiece 6 to be machined. The the circular cavity comprises two hollow hemispheres, a first hemisphere 7 and a second hemisphere 9, which being connected to each other by means of a sealing device. The the sealing means comprises a locating pin 2, a bolted connector 1 and a serrated sealing structure 3 located at the union of the first hemisphere 7 and the second hemisphere 9. Locating the connection between the first hemisphere 7 and the second hemisphere 9 by means of the locating pin 2, the locating pin 2 being a conical pin, which ensures the precision of the positioning of the first hemisphere 7 and the second hemisphere 9 and ensures that the first hemisphere 7 and the second hemisphere 9 form a precision spherical space. The serrated sealing structure 3 ensures that no leakage occurs when the first hemisphere 7 is connected to the second hemisphere 9. Finally, a sufficiently high connection strength is ensured by means of the bolting member 1 when the first hemisphere 7 is connected to the second hemisphere 9. The first hemisphere 7 is provided with a grit stream inlet 8 and the second hemisphere 9 is provided with a grit stream outlet 17. The first hemispherical body 7 is provided with a first main flow channel, the first main flow channel being connected to the abrasive grain flow inlet 8 and the cavity, respectively. The second hemisphere 9 is provided with a second main flow channel, the second main flow channel being connected to the abrasive grain flow outlet 17 and the cavity. The abrasive grain stream 10 forms a circulation loop between the abrasive grain stream inlet 4, the circular cavity and the abrasive grain stream outlet 17 by means of a circulation device. The first main flow path and the second main flow path are not connected to each other, and each of the first main flow paths is provided with a number of abrasive grain flow inlet holes 8 connected to the cavity. The abrasive grain flow inlet hole 8 tapers in the flow direction. Each the second main flow path is provided with a number of abrasive flow return holes 11 connected to the cavity, the abrasive flow return holes 11 tapering in the flow direction. In the embodiment the abrasive grain flow inlet aperture 8 and the abrasive grain flow return aperture 11 are conical apertures, respectively. The abrasive grain flow inlet holes 4 and abrasive grain flow return holes 11 can direct the flow direction of the abrasive grain flow 10. The axis of each of the abrasive flow inlet holes 4 and abrasive flow return holes 11 form an angle of 20° to 45° in the direction of the radius in which they are located. Such a setting enables the abrasive grain stream 10 to drive the workpiece 6 to make a counterclockwise rotation, thereby removing the workpiece projections 22 of the workpiece 6 by precision machining of the workpiece projections 22 on the surface of the workpiece 6 by the abrasive grain stream 10. The axes of both the preferred abrasive flow inlet aperture 4 and the abrasive flow return aperture 11 form an angle of 35° with the radius direction in which they are located. The circulating means comprising an abrasive stream delivery pipe 19, a pressure pump 18, an abrasive stream recovery device 20 and a pressure valve 21. The abrasive grain stream outlet 17 of the second hemispherical body 9 is connected to an abrasive grain stream recovery device 20 via an abrasive grain stream delivery pipe 19. The abrasive grain stream recovery device 20 being connected to the inlet of a pressure pump 18. The abrasive stream recovery unit 20 is configured to recover the filtered abrasive stream 10. The pressure pump 18 outlet being connected to the abrasive grain stream inlet 4 of the first hemisphere 7. The abrasive grain stream outlet 17 is fitted with a pressure valve 21 for determining the pressure of the abrasive grain stream 10. The abrasive stream 10 flowing from the abrasive stream outlet 17 passes through a pressure valve 18 into an abrasive stream recovery device 20. The abrasive stream recovery device 20 recycles and filters the abrasive stream 10 and continues to be conveyed by the pressure pump 18 to the abrasive stream inlet 8. The abrasive grain stream 10 circulates in the circular cavity under the action of the pressure pump 18 and continuously performs precision machining on the surface of the workpiece 6. The abrasive grain stream inlet 4 and abrasive grain stream outlet 17 are provided with duct seals. The pipe sealing means comprising a pipe fitting thread 14, a connecting pipe 15 and a sealing washer 16. Taking the grit stream outlet 17 as an example, the pipe fitting thread 14 is provided on the grit stream outlet 17, the connecting pipe 15 is threaded onto the grit stream outlet 17, and a sealing washer 16 is passed between the connecting pipe 15 and the grit stream outlet 17 for improving sealing performance. The circulation system is also connected to a control system 12, wherein the control system 12 can determine the value of the flow pressure of the abrasive grain stream 10 according to the machining allowance of the workpiece 6 to be machined, prior to the commencement of the precision machining work. While the precision machining work is in progress, the control system 12 is further connected to vibration sensors 5 provided on the inner walls of the first hemisphere 7 and the second hemisphere 9. The vibration sensor 5 is connected to the control system 12 by means of a signal line 13, and according to the different vibration signals of the abrasive grain stream 10 at the workpiece protrusion 22 and the workpiece levelling 23, the completion of the precision machining of the workpiece 6 is judged by the smoothness of the signals transmitted from the vibration sensor 5, and thus the value of the flow pressure of the abrasive grain stream 10 is adjusted by means of the control system 12. The control system 12 regulates the output pressure of the circulation device according to the vibration signal. If the workpiece 6 has completed the precision machining, the control system 12 automatically and gradually reduces the value of the flow pressure of the abrasive grain stream 10 to 0 by means of the pressure pump 18. In addition, the abrasive grains of the abrasive grain stream 10 can be processed in a wide range of metallic and non-metallic spheres by determining the material, grain size, etc. of the abrasive grain stream 10 according to the material and properties of the workpiece 6. Taking high-precision bearing steel balls as an example, the method of the ball precision machining device described in the present disclosure, as shown in FIG. 3, comprises the following steps: According to the requirements of the processed high-precision bearing steel balls, 4000# grain size AI2O3 abrasive grains are selected, and the abrasive grain flow pressure is 0.04-0.1 MPa. The first setting value of 0.01 mm / s is determined according to the material properties. The workpiece 6 to be processed and the entire unit are cleaned. The workpiece 6 is placed into the circular cavity and the connection between the first hemisphere 7 and the second hemisphere 9 is positioned by means of the positioning pin 2. The serrated sealing structure 3 ensures that no leakage occurs when the first hemisphere 7 and the second hemisphere 9 are connected. The bolted connector 1 ensures that the first hemisphere 7 and the second hemisphere 9 can have a sufficiently high connection strength when connected. Bolt tightening torque: 3.5 N*m. An abrasive grain stream 10 is passed into the circular cavity and the circulation device is switched on so that the abrasive grain stream 10 can flow continuously in the circular cavity to perform precision machining of the workpiece 6. The initial state sets the circulation device output pressure Po to 0.04 MPa. A number of vibration sensors 5 detect vibration signals generated by the abrasive grain stream 10, and the control system adjusts the output pressure of the circulation device according to the vibration signals, specifically: After a processing time of 20 minutes, the control system 12 compares the average value Sti of a number of vibration signals with a first set value, the first set value being taken as 0.01 mm / s, and when the average value Su is less than 0.01 mm / s, the grinding process is completed. When the average value Sti is greater than 0.01 mm / s, the control system 12 increases the output pressure of the circulating means to Pi = 0.06 MPa. After 20 minutes time of processing after adjusting the pressure, when the average value St2 is greater than 0.01 mm / s and the average value St2 is less than the average value Sti, then the control system reduces the output pressure of the circulating device to P2=0.05 MPa and Pi>P2>Po, until the average value Sti is less than the first set value. And as shown in Table 1, the control system 12 determines the size of the output pressure of the adjusting circulation device based on the average value S of the vibration signal. After the grinding process is completed, the workpiece 6 is taken out to detect whether the shape accuracy and surface quality meet the set requirements, if not, it is put back into the cavity for processing. Open the first hemisphere 7 and the second hemisphere 9, take out the workpiece, measure the workpiece 6, and if the accuracy of the workpiece 6 does not meet the requirements, continue to put it into the circular cavity for machining. Table 1 Average value of vibration signals (mm / s) Pressure pump values (MPa) <0.01 No adjustment required 0.01-0.02 0.05 0.02-0.03 0.06 0.03-0.04 0.07 0.04-0.05 0.08 0.06-0.07 0.09 >0.07 0.1 It should be understood that although this specification is described in accordance with various embodiments, not each embodiment contains only one independent technical solution, and this description of the specification is only for the sake of clarity, and the person skilled in the art should take the specification as a whole, and the technical solutions in the various embodiments can be combined appropriately to form other embodiments that can be understood by the person skilled in the art. The above listed series of detailed description is only for the feasible embodiments of the present disclosure, they are not intended to limit the scope of protection of the present disclosure, all not out of the spirit of the art of the present disclosure equivalent embodiments or changes should be included in the scope of protection of the present disclosure.

Claims

What is claimed is:

1. A sphere precision machining device, comprising a cavity, an abrasive grain stream (10), and a circulation device, wherein the cavity holds a workpiece (6), the cavity consists of two hollow hemispheres (7, 9), and the two hemispheres (7, 9) are each provided with a main flow channel, the main flow channel being connected to the cavity; one end of the main flow path of each of the two hemispheres (7, 9) is connected to a circulating device, and by means of the circulating device, a stream of abrasive grains (10) grinds the workpiece (6); and a plurality of main flow channels are disposed homogeneously inside the hemispheres (7, 9), and each of the main flow channels is provided with a plurality of branched flow channels connecting to the cavities, the branched flow channels being tapered in a flow direction.

2. The sphere precision machining device according to claim 2, characterized in that an axis of a branched runner is at an angle of 20° to 45° to a radius direction in which it is located, so that the workpiece (6) is rotated counterclockwise by the impact of the abrasive grain stream (10).

3. The sphere precision machining device according to claim 1, characterized in that a sealing assembly is provided for sealing between the docking surfaces of the two hemispheres (7, 9).

4. The sphere precision machining device according to claim 1, further comprising a control system, a vibration sensor (5), and a pressure sensor;a number of the vibration sensors (5) are mounted on the inner wall of the cavity for detecting vibration signals generated by an abrasive grain flow (10);the pressure sensor is configured to detect the pressure of the abrasive grain stream (10) at the output of the circulation device; andthe control system regulates the output pressure of the circulation device in accordance with the vibration signal.

5. A processing method of the sphere precision machining device according to any one of claims 1 to 5, further comprising steps of:placing the workpiece (6) into the cavity and installing the hemispheres (7, 9) in a sealed manner;pumping the abrasive grain stream (10) to the cavity grinding workpiece (6) by means of a circulation device;detecting, by a number of vibration sensors (5), vibration signals generated by an abrasive grain flow (10), and regulating, by a control system, the output pressure of the circulation device accordingto the vibration signals; andafter a grinding process is completed, taking out the workpiece (6) to check whether the shape accuracy and surface quality meet the set requirements, if not, putting the workpiece back into the cavity for processing.

6. The processing method of the sphere precision machining device according to claim 5, characterized in that the control system adjusts the output pressure of the circulation device according to the vibration signal, further comprising:as an initial state, setting the output pressure of the circulation device to Po;after processing for a time ti, comparing, by the control system, the average value Sti of a number of vibration signals with a first set value according to the average value Su of the number of vibration signals, and when the average value Sti is less than the first set value, completing the grinding process; andwhen the average value Sti is greater than the first set value, increasing, by the control system, the output pressure of the circulation device to Pi; after adjusting the pressure and processing for a time t2, when the average value Sc is greater than the first set value and the average value St2 is less than the average value St2, reducing, by the control system, the output pressure of the circulation device to P2, wherein Pi>P2>Po, until the average value Sti is less than the first set value.INTERNATIONAL SEARCH REPORT International application No. PCT / CN2023 / 091248A. CLASSIFICATION OF SUBJECT MATTER B24B31 / 116(2006.01)i; B24B31 / 112(2006.01)i According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC:B24B31 B24B11 Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) CNTXT, DWPI, ENTXT, VEN, WPABSC, CJFD: JgJttJW, S®, MJt, WW, WM 3JE, 0$?, Mil, IBjK, spher+, ball, mill, grain?, abrasive?, polish+, grind+, antrum, cavity, hollow, channel C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. A CN 109986455 A (THE BOEING COMPANY) 09 July 2019 (2019-07-09) description, paragraphs 16-63, and figures 1-7 1-6 A CN 102170999 A (NTN TOYO BEARING CO., LTD.) 31 August 2011 (2011-08-31) entire document 1-6 A CN 105108632 A (ZHEJIANG UNIVERSITY OF TECHNOLOGY) 02 December 2015 (2015-12-02) entire document 1-6 A CN 108161754 A (ZHEJIANG UNIVERSITY OF TECHNOLOGY) 15 June 2018 (2018-06-15) entire document 1-6 A CN 206305962 U (SHENYANG AEROSPACE XINGUANG GROUP CO., LTD.) 07 July 2017 (2017-07-07) entire document 1-6 A JP 2008238360 A (UNIVERSITY OF YAMANASHI) 09 October 2008 (2008-10-09) entire document 1-6 | Z | Further documents are listed in the continuation of Box C. | J | See patent family annex. * Special categories of cited documents: “A” document defining the general state of the art which is not considered to be of particular relevance ■‘D” document cited by the applicant in the international application “E” earlier application or patent but published on or after the international filing date “L” document which may throw doubts on priority claim(s) or which is cited to establish the publication date of another citation or other special reason (as specified) “O” document referring to an oral disclosure, use, exhibition or other means “P” document published prior to the international filing date but later than the priority date claimed “T” later document published after the international filing date or priority date and not in conflict with the application but cited to understand the principle or theory underlying the invention “X” document of particular relevance; the claimed invention cannot be considered novel or cannot be considered to involve an inventive step when the document is taken alone “Y” document of particular relevance; the claimed invention cannot be considered to involve an inventive step when the document is combined with one or more other such documents, such combination being obvious to a person skilled in the ait document member of the same patent family Date of the actual completion of the international search Date of mailing of the international search report 22 December 2023 04 January 2024 Name and mailing address of the ISA / CN Authorized officer China National Intellectual Property Administration (ISA / CN) China No. 6, Xitucheng Road, Jimenqiao, Haidian District, Beijing 100088 Telephone No.INTERNATIONAL SEARCH REPORT International application No. PCT / CN2023 / 091248c.DOCUMENTS CONSIDERED TO BE RELEVANTCategory* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. A JP H02190251 A (TOSHIBA CORP.) 26 July 1990 (1990-07-26) entire document 1-6 A US 2008271380 Al (NATIONAL CENTRAL UNIVERSITY) 06 November 2008 (2008-11-06) entire document 1-6INTERNATIONAL SEARCH REPORT Information on patent family members International application No. PCT / CN2023 / 091248Patent document cited in search report Publication date (day / month / year) Patent family member) s) Publication date (day / month / year) CN 109986455 A 09 July 2019 JP 2019171558 A 10 October 2019 JP 7226989 B2 21 February 2023 US 2019202023 Al 04 July 2019 US 11577355 B2 14 February 2023 EP 3505298 A2 03 July 2019 EP 3505298 A3 11 March 2020 EP 3505298 Bl 17 November 2021 CN 102170999 A 31 August 2011 WO 2010038646 Al 08 April 2010 US 2011177760 Al 21 July 2011 US 9089947 B2 28 July 2015 JP 2010089170 A 22 April 2010 JP 5334040 B2 06 November 2013 EP 2351630 Al 03 August 2011 EP 2351630 A4 07 November 2012 EP 2351630 Bl 24 July 2013 CN 105108632 A 02 December 2015 None CN 108161754 A 15 June 2018 None CN 206305962 U 07 July 2017 None JP 2008238360 A 09 October 2008 JP 4982857 B2 25 July 2012 JP H02190251 A 26 July 1990 None US 2008271380 Al 06 November 2008 TW 200843903 A 16 November 2008 TWI 318911 B 01 January 2010 US 7814679 B2 19 October 2010 US 2008271382 Al 06 November 2008

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