Workpiece machining positioning fixture and method

Abstract

The application discloses a workpiece machining positioning clamp and method, the clamp comprises a base, concentric positioning device and axial positioning device; the base is horizontally arranged, the concentric positioning device is embedded in the mounting groove of the base, and the clamping working end of the concentric positioning device extends upwards; the workpiece to be machined is provided with a through central hole in the axial direction, and the lower part of the central hole forms a limiting hole; the workpiece is horizontally placed on the base, the clamping working end of the concentric positioning device is in abutment with the hole wall of the limiting hole of the workpiece; the axial positioning device is arranged in the axial direction along the central hole of the workpiece, the outer wall of the upper section of the axial positioning device is in abutment with the inner wall of the central hole of the workpiece, the lower part of the axial positioning device is connected and fixed with the concentric positioning device, and the lower end of the axial positioning device is connected with the locking member arranged in the cavity of the base. The application has the beneficial effects that the concentric positioning device is used to abut against the limiting hole of the workpiece, and the axial positioning device is used to abut against the central hole of the workpiece, so that the problem of insufficient positioning precision of the existing clamp when the complex curved surface and the thin-walled asymmetric structure of the centrifugal impeller are machined is solved.

Description

Technical Field

[0001] This invention relates to the field of parts clamping technology, specifically to a workpiece machining positioning fixture and method. Background Technology

[0002] Fixtures are the bridge connecting workpieces and machine tools, playing a crucial role in parts machining. They ensure machining accuracy and quality through precise positioning and stable clamping, while improving efficiency and shortening cycle time through rapid clamping and multi-station machining. General-purpose fixtures offer advantages such as wide applicability, low cost, and high flexibility, making them suitable for small-batch, multi-variety, or simple machining scenarios. However, they suffer from limited positioning accuracy, low clamping efficiency, insufficient specificity, and difficulty in integration with automated equipment, failing to meet the demands of high-precision, complex parts or mass production. For example, existing general-purpose fixtures have significant shortcomings in centrifugal impeller machining: their reliance on external diameter or end face positioning is ill-suited to the complex curved surfaces, asymmetrical structures, and thin-walled features of impellers, leading to insufficient positioning accuracy, uneven clamping force distribution causing deformation, and the accumulation of repeated positioning errors during multi-face machining, which can increase critical dimensional errors. Furthermore, it is difficult to ensure datum consistency during offline inspection.

[0003] Therefore, there is an urgent need for a new fixture and method to solve the problems of insufficient positioning accuracy and low clamping efficiency in the five-axis milling of centrifugal impellers in the existing technology, so as to realize reliable positioning and rapid automatic clamping of workpieces during the machining process. Summary of the Invention

[0004] The purpose of this invention is to provide a workpiece machining positioning fixture and method to address the shortcomings of existing technologies, thereby solving the problem of insufficient positioning accuracy in existing technologies.

[0005] The technical solution adopted in this invention is: a workpiece machining positioning fixture, comprising a base, a concentric positioning device and an axial positioning device; The base is horizontally arranged, and its upper surface has a mounting groove for assembling the concentric positioning device; the bottom of the base is provided with a cavity. The concentric positioning device is embedded in the mounting groove of the base, with the clamping working end of the concentric positioning device extending upwards; A through-hole is opened in the workpiece along the axial direction, and the lower part of the through-hole extends radially outward to form a limiting hole; the workpiece is placed horizontally on the upper end face of the base, and the clamping working end of the concentric positioning device is pressed against the wall of the limiting hole of the workpiece. The axial positioning device is arranged axially through the center hole of the workpiece; the upper outer wall of the axial positioning device is tightly fitted with the inner wall of the center hole of the workpiece to achieve matching and limiting; the lower part of the axial positioning device is connected and fixed to the concentric positioning device; the lower end of the axial positioning device is connected to the locking member provided in the cavity of the base.

[0006] According to the above scheme, the concentric positioning device includes a housing, a slide rail, a slider, a positioning column, a rotary drive mechanism, and a transmission assembly; The box body has a hollow structure and is formed by a chassis and a box cover assembled on top of the chassis. The box cover is provided with a box surface positioning keyway that is adapted to the lower end of the axial positioning device, and a strip hole that is adapted to the movement trajectory of the positioning column. At least three slide rails are evenly spaced around the center of the chassis, with each slide rail extending in the same direction as the radial direction of the chassis. A slider is slidably mounted on a single slide rail, and the slider is fastened to the bottom end of the positioning post. The rotary drive mechanism is located at the center of the chassis, and the drive end of the rotary drive mechanism is connected to the input side of the transmission component. The transmission component has output ends that are evenly distributed along the circumference and correspond one-to-one with the number of sliders. Each output end of the transmission component is connected to the corresponding slider.

[0007] According to the above scheme, the rotary drive mechanism adopts a drive motor; the transmission assembly includes a driving gear, a driven gear, a rotating connecting block, and multiple transmission rods; the driving gear is assembled at the output end of the drive motor, and the central axis of the driving gear is coaxially and fixedly connected to the motor shaft of the drive motor; the driven gear is installed on the side of the driving gear and meshes with the driving gear for transmission; the driven gear is located on the outer circumferential surface of the hollow cylinder, the upper end surface of the hollow cylinder is rigidly fixed to the center of the bottom surface of the rotating connecting block, the bottom of the hollow cylinder passes through the chassis and is fixedly connected to the rotating disk below the chassis, and the rotating disk is rotatably connected to the chassis through bearings; the outer edge of the rotating connecting block has connection positions evenly arranged circumferentially, corresponding one-to-one with the number of sliders, and each connection position is hinged to a transmission rod, the end of the transmission rod away from the rotating connecting block is connected to the corresponding slider.

[0008] According to the above scheme, the axial positioning device includes a boss threaded shaft and an expansion mechanism; the expansion mechanism consists of an upper rotating part, a lower sliding part, and multiple linkage arms; The upper rotating part is threadedly engaged with the boss threaded shaft, and the lower sliding part is slidably fitted onto the outer circumference of the boss threaded shaft; a positioning key is fixedly provided at the bottom end of the lower sliding part, and the positioning key is matched with the positioning keyway of the box surface opened on the upper end face of the box cover.

[0009] According to the above scheme, a single boom consists of an upper boom and a lower boom connected by a hinge, and the connection part of the two forms a connecting bend section; the upper end of the upper boom is hinged to the outer wall of the upper rotating component, and the lower end of the lower boom is hinged to the outer wall of the lower sliding component; the connecting bend section presses outward against the inner wall of the center hole of the workpiece.

[0010] According to the above scheme, the workpiece and the upper surface of the base are provided with corresponding pin holes.

[0011] According to the above scheme, both the rotating connecting block and the rotating disk are provided with through holes for the lower end of the axial positioning device to pass through.

[0012] According to the above scheme, the lower end of the hollow cylinder is provided with threaded holes at intervals around the circumference, which are adapted to the screws. The hollow cylinder is fixed on the rotating disk by connecting the threaded holes of the rotating disk and the threaded holes of the hollow cylinder with screws; the rotating disk is located below the chassis.

[0013] This invention also employs a workpiece machining clamping method, which utilizes the workpiece machining positioning fixture described above; characterized in that the method includes the following steps: Step 1: Assemble the concentric positioning device of the workpiece machining positioning fixture into the base, retract all sliders to the minimum limit stroke, place the workpiece to be processed, and complete the preparation before clamping. Step 2: After the workpiece is placed in place, the drive motor of the concentric positioning device starts, driving multiple sets of sliders to expand radially in sync, and each positioning column moves radially outward in sync, pressing against the wall of the limiting hole at the bottom of the workpiece to complete the concentric centering of the workpiece. Step 3: Use an axial positioning device to provide axial support and positioning for the workpiece; first, adjust the expansion mechanism fitted outside the boss threaded shaft to the fully retracted state, and insert the entire axial positioning device into the center hole of the workpiece; the positioning key at the bottom of the expansion mechanism is embedded in the positioning keyway on the surface of the cover, and the lower sliding part cannot slide axially. The rotating boss threaded shaft, the upper rotating part and the boss threaded shaft form a threaded pair transmission, and the upper rotating part is locked by the lower sliding part. The upper rotating part feeds downward along the boss threaded shaft. The distance between the upper rotating part and the lower sliding part decreases, and the upper and lower moving arms are squeezed to swing outward around the hinge point until the connecting bending section of the upper and lower moving arms synchronously presses against the inner wall of the center hole of the workpiece, forming uniform support for the center hole of the workpiece. Step 4: Continue to rotate the threaded shaft of the boss downwards until the expansion mechanism stops. Then, tighten the lower locking nut to lock all axial degrees of freedom of the workpiece. At the same time, the milling cutting load is shared by the connecting bending section. The workpiece is clamped and the machining process is started. Step 5: After the workpiece is processed, remove the clamps.

[0014] According to the above scheme, the specific method of step five is as follows: loosen the locking nut in the inner cavity of the base in the reverse direction, rotate the threaded shaft of the boss in the reverse direction to move the upper rotating part upward, and retract each set of moving arms inward to release the support of the inner hole of the workpiece; drive the motor to rotate in the reverse direction, driving all the sliders and positioning pins to retract along the slide rail to the minimum stroke; take the processed workpiece out from above the fixture.

[0015] The beneficial effects of this invention are as follows: 1. This invention designs a concentric positioning device and an axial positioning device. The concentric positioning device tightens the workpiece limiting hole, and the axial positioning device expands the workpiece center hole, replacing the traditional general-purpose fixture's single outer circle or end face positioning mode. This completely solves the problems of positioning datum deviation and insufficient positioning accuracy of existing fixtures when machining complex curved surfaces and thin-walled asymmetrical structures of centrifugal impellers. It effectively avoids radial offset and end face wobbling problems during workpiece machining, and ensures the machining accuracy of key dimensions in five-axis milling of impellers.

[0016] 2. The concentric positioning device in this invention adopts a radial expansion positioning structure with circumferentially uniformly arranged slide rails and sliders in conjunction with positioning columns. The transmission components realize the synchronous linkage of multiple sets of positioning columns, which can achieve circumferential uniform force clamping and positioning of the workpiece limit hole. Compared with the traditional single-point and single-side clamping method of fixtures, the clamping force is evenly distributed, which can effectively avoid the processing deformation caused by uneven force on thin-walled impeller workpieces. At the same time, the circumferentially uniform positioning structure can accurately constrain the circumferential rotational freedom of the workpiece, further improving the positioning stability and concentricity accuracy of the workpiece after clamping.

[0017] 3. In this invention, an automated transmission structure with drive motor, gear meshing, and transmission rod linkage is used to realize the synchronous radial expansion and contraction of multiple sets of positioning columns. There is no need for manual calibration of the positioning position one by one. The workpiece can be concentrically centered, which greatly improves the workpiece clamping efficiency, ensures the positioning uniformity of batch workpiece clamping, and is suitable for the production needs of batch five-axis milling of impellers.

[0018] 4. The axial positioning device in this invention adopts an expansion mechanism structure with threaded transmission and keyway limiting. The expansion range of the boom can be precisely adjusted through the thread to achieve adaptive expansion support for the center hole of the workpiece. It can be adapted to the clamping of impeller workpieces with different hole diameters, solving the problems of poor adaptability of traditional special fixtures and insufficient support stability of general fixtures. Attached Figure Description

[0019] Figure 1 This is the assembly front view of Example 1.

[0020] Figure 2 This is a cross-sectional view of assembly AA in Example 1.

[0021] Figure 3This is a schematic diagram of the overall structure of the concentric positioning device in Example 1 (the slider is at its maximum limit position).

[0022] Figure 4 This is a schematic diagram of the chassis structure of the concentric positioning device in Embodiment 1.

[0023] Figure 5 This is a schematic diagram of the slider of the concentric positioning device in the first embodiment being in its minimum position.

[0024] Figure 6 This is a schematic diagram showing the disassembled concentric positioning device in Embodiment 1.

[0025] Figure 7 This is a schematic diagram of the connection between the box cover and the positioning pin in Example 1.

[0026] Figure 8 This is a schematic diagram showing the connection between the hollow cylinder, the driven gear, and the rotating connecting block in Example 1.

[0027] Figure 9 This is a schematic diagram of the axial positioning device in Embodiment 1.

[0028] Figure 10 This is a schematic diagram of the expansion mechanism of the axial positioning device in Embodiment 1.

[0029] Figure 11 This is a schematic diagram of the bottom of the workpiece after positioning in Example 2.

[0030] Figure 12 This is a cross-sectional view of the workpiece positioning state in Example 2.

[0031] In the diagram: 1. Chassis; 2. Positioning pin; 3. Single-column slider; 4. Single-column slider threaded hole; 5. Single-column slider threaded sleeve; 6. Upper transmission rod rear threaded hole; 7. Upper connection rear bolt; 8. Upper transmission rod; 9. Upper transmission rod front threaded hole; 10. Upper connection front bolt; 11. Cover; 12. Lower connection front bolt; 13. Rotating connecting block; 14. Lower transmission rod; 15. Lower connection rear bolt; 16. Double-column slider front threaded sleeve; 17. Double-column slider rear threaded sleeve; 18. Double-column slider; 19. Slide rail; 20. Drive gear; 21. Drive motor; 22. Rotating disk; 23. Screw; 24. Rotating connecting block threaded hole; 25. Driven gear; 26. 1. Hollow cylinder bottom threaded hole; 27. Boss threaded shaft; 28. Shaft end clamping block; 29. ​​Locating key; 30. Expansion mechanism; 31. Upper moving arm; 32. Lower moving arm; 33. Lower sliding part; 34. Upper rotating part; 35. Workpiece; 36. Center hole; 37. Limiting hole; 38. Base; 39. Mounting groove; 40. Locking nut; 41. Box surface locating keyway; 42. Workpiece pin hole; 43. Locating pin; 44. Base pin hole; 45. Concentric positioning device; 46. Axial positioning device; 47. Lower transmission rod front threaded hole; 48. Lower transmission rod rear threaded hole; 49. Rotating disk threaded hole; 50. Motor pressure sensor; 51. Motor resistance detection module; 52. Hollow cylinder. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] In the description of the embodiments of this application, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0035] In the embodiments of this application, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples. Additionally, the term "a plurality of" indicates two or more.

[0037] The automatic positioning fixture provided by this invention can be used for circumferential, radial and axial positioning and clamping of workpieces 35 such as centrifugal impellers.

[0038] like Figure 1 and Figure 2 The workpiece machining positioning fixture shown includes a base 38, a concentric positioning device 45 and an axial positioning device 46. The base 38 is horizontally arranged, and its upper end face has an installation groove 39 for assembling the concentric positioning device 45; the bottom of the base 38 is provided with a cavity. The concentric positioning device 45 is embedded in the mounting groove 39 of the base 38, with the clamping working end of the concentric positioning device 45 extending upwards. The workpiece 35 to be processed has a through central hole 36 along the axial direction. The lower part of the central hole 36 extends radially outward to form a limiting hole 37. The workpiece 35 is placed horizontally on the upper surface of the base 38. The clamping working end of the concentric positioning device 45 can be pressed against the wall of the limiting hole 37 of the workpiece 35. The axial positioning device 46 is arranged axially through the center hole 36 of the workpiece 35; the upper outer wall of the axial positioning device 46 is tightly fitted with the inner wall of the center hole 36 of the workpiece 35 to achieve matching and limiting; the lower part of the axial positioning device 46 is connected and fixed to the concentric positioning device 45; the lower end of the axial positioning device 46 is connected to the locking member provided in the cavity of the base 38.

[0039] In this invention, the centering constraint of the workpiece 35 is completed synchronously by the concentric positioning device 45, so that the center of the inner hole of the workpiece 35 is completely aligned with the rotation center of the fixture. The axial positioning device 46 realizes the axial clamping and positioning of the workpiece 35, and achieves precise clamping of the workpiece 35 in all dimensions.

[0040] Preferably, such as Figures 3-8 As shown, the concentric positioning device 45 includes a housing, a slide rail 19, a slider, a positioning column 2, a rotary drive mechanism, and a transmission assembly; The box body has a hollow structure and is formed by the chassis 1 and the box cover 11 that can be detachably assembled on the top of the chassis 1. The box cover 11 is provided with a box surface positioning keyway 41 adapted to the lower end of the axial positioning device 46, and a strip hole adapted to the movement trajectory of the positioning column 12. At least three slide rails 19 are evenly spaced around the center of the chassis 1, with each slide rail 19 extending in the same direction as the radial direction of the chassis 1. A slider is slidably mounted on a single slide rail 19, and the slider is fastened to the bottom end of the positioning post 2. The rotary drive mechanism is located at the center of the chassis 1, and the drive end of the rotary drive mechanism is connected to the input side of the transmission component. The transmission component has output ends that are evenly distributed along the circumference and correspond one-to-one with the number of sliders. Each output end of the transmission component is connected to the corresponding slider.

[0041] In this invention, the upper end of the positioning post 2 protrudes through the strip hole on the box cover 11; the rotary drive mechanism drives the transmission assembly to rotate, and the transmission assembly drives each slider to slide radially synchronously along the corresponding slide rail 19. The slider drives the positioning post 2 to synchronously feed radially until multiple positioning posts 2 synchronously press against the wall of the bottom limiting hole 37 of the workpiece 35, thereby achieving concentric positioning of the workpiece 35. The maximum and minimum limit positions of the slider are as follows: Figure 3 and Figure 5 As shown.

[0042] Preferably, the rotary drive mechanism is a drive motor 21 with an integrated electromagnetic brake.

[0043] Preferably, the transmission assembly includes a driving gear 20, a driven gear 25, a rotating connecting block 13, and multiple transmission rods; the driving gear 20 is mounted on the output end of the drive motor 21, and the central shaft of the driving gear 20 is coaxially and rigidly connected to the motor shaft of the drive motor 21; the driven gear 25 is located on the side of the driving gear 20 and meshes with the driving gear 20 for transmission; the driven gear 25 is located on the outer circumferential surface of the hollow cylinder 52, the upper end face of the hollow cylinder 52 is rigidly fixed to the center of the bottom surface of the rotating connecting block 13, the bottom of the hollow cylinder 52 passes through the chassis 1 and is fixedly connected to the rotating disk 22 below the chassis 1, and the rotating disk 22 is rotatably connected to the chassis 1 through a bearing; the outer edge of the rotating connecting block 13 has connection positions evenly arranged circumferentially, corresponding one-to-one with the number of sliders, and each connection position is hinged to a transmission rod, the end of the transmission rod away from the rotating connecting block 13 is connected to the corresponding slider.

[0044] In this invention, the ends of each transmission rod connected to the slider constitute the output end of the transmission assembly; the drive motor 21 outputs torque to drive the drive gear 20 to rotate, and the drive gear 20 meshes with the driven gear 25 to rotate synchronously, and the driven gear 25 drives the rotating connecting block 13 to rotate around the central axis as a whole; the rotating connecting block 13 pushes and pulls each slider synchronously through multiple transmission rods, driving the slider and the positioning column 2 to make radial synchronous feeding movements along the slide rail 19.

[0045] In this invention, both the rotating connecting block 13 and the rotating disk 22 are provided with through holes for the lower end of the axial positioning device 46 to pass through.

[0046] Preferably, such as Figure 9 and Figure 10 As shown, the axial positioning device 46 includes a boss threaded shaft 27 and an expansion mechanism 30; the expansion mechanism 30 includes an upper rotating member 34, a lower sliding member 33 and multiple linkage arms.

[0047] The upper rotating part 34 is threadedly engaged with the boss threaded shaft 27, and the lower sliding part 33 is slidably fitted on the outer periphery of the boss threaded shaft 27; a positioning key 29 is fixedly provided at the bottom end of the lower sliding part 33, and the positioning key 29 is matched with the box surface positioning keyway 41 opened on the upper end surface of the box cover 11 to limit the circumferential rotation of the lower sliding part 33.

[0048] Preferably, a single boom consists of an upper boom 31 and a lower boom 32 connected by a hinge, with the connection point forming a connecting bend section; the upper end of the upper boom 31 is hinged to the outer wall of the upper rotating member 34, and the lower end of the lower boom 32 is hinged to the outer wall of the lower sliding member 33; the connecting bend section of the upper boom 31 and the lower boom 32 can press outward against the inner wall of the center hole 36 of the workpiece 35.

[0049] In this invention, the rotating boss threaded shaft 27 drives the upper rotating component 34 to move axially up and down via the threaded pair; the lower sliding component 33 is restricted from axial movement by the positioning key 29 and the positioning keyway 41 on the box surface, and the axial distance between the upper rotating component 34 and the lower sliding component 33 changes, causing multiple sets of booms to swing outward and simultaneously tighten the center hole 36 of the workpiece 35; after the upper rotating component 34 is locked in place, the boss threaded shaft 27 is continuously screwed down to pass through the concentric positioning device 45 (passing through the box cover 11, the rotating connecting block 13, the hollow cylinder 52 and the rotating disk 22 in sequence), and is tightly fitted with the locking nut 40 (i.e. the aforementioned locking component) in the cavity of the base 38; the locking nut 40 is hidden inside the cavity of the base 38 and is not exposed, and the workpiece 35 is reliably positioned axially by means of the threaded locking force.

[0050] Preferably, the workpiece 35 to be processed and the upper surface of the base 38 are provided with pin holes that correspond to each other and are adapted to the positioning pins 43.

[0051] In this invention, the positioning pin 43 is used for the initial circumferential positioning of the workpiece 35 and the base 38, and the final concentric centering of the workpiece 35 is completed by the concentric positioning device 45; the positioning pin 43 can be removed after the workpiece 35 is processed.

[0052] Example 1 This embodiment relates to a workpiece machining positioning fixture, mainly used for positioning and clamping a centrifugal impeller workpiece 35 during milling. In addition to the structure described above, this embodiment also includes the following configuration.

[0053] In this embodiment, the upper surface of the base 38 is used as the horizontal reference plane; the side closer to the base 38 is the bottom, and the side farther from the base 38 is the top; the side closer to the central axis of the fixture is the inner side, and the side farther from the central axis is the outer side.

[0054] In this embodiment, reference Figure 3 , 45, 6. Four slide rails 19 are evenly arranged circumferentially on the chassis 1, corresponding to four sliders, four transmission rods, and four positioning pins 2; the four structures are arranged symmetrically in two groups. Among the four transmission rods, two are upper transmission rods 8. One end of each upper transmission rod 8 is connected to the upper part of the rotating connecting block 13 through a corresponding upper connecting front bolt 10, and the other end of each upper transmission rod 8 is connected to the corresponding slider through a corresponding upper connecting rear bolt 7. The slider is a double-column slider 18, and the upper connecting rear bolt 7 is specifically connected to the double-column slider front threaded sleeve 16 on the double-column slider 18. The upper transmission rod 8 has an upper transmission rod front threaded hole 9 that matches the upper connecting front bolt 10, and an upper transmission rod rear threaded hole 6 that matches the upper connecting rear bolt 7. The other two transmission rods are lower transmission rods 14. One end of each lower transmission rod 14 is connected to the lower part of the rotating connecting block 13 via a corresponding lower connecting front bolt 12. The other end of each lower transmission rod 14 is connected to a corresponding slider via a corresponding lower connecting rear bolt 15. The slider is a single-column slider 3, and the single-column slider 3 has a single-column slider threaded hole 4 that matches the lower connecting rear bolt 15. The lower transmission rod 14 has a lower transmission rod front threaded hole 47 that matches the lower connecting front bolt 12, and a lower transmission rod rear threaded hole 48 that matches the lower connecting rear bolt 15. The rotating connecting block 13 has four rotating connecting block threaded holes 24, which are respectively matched with the upper connecting front bolt 10 and the lower connecting front bolt 12.

[0055] In this embodiment, each slider is provided with a threaded sleeve, and each slider is connected to the corresponding positioning post 2 through the threaded sleeve. Among them, the threaded sleeve 5 is provided on the single-post slider 3, and the threaded sleeve 17 is provided on the double-post slider 18.

[0056] In this embodiment, reference Figure 8 The hollow cylinder 52 has circumferentially spaced threaded holes 26 at the bottom end of the hollow cylinder that are adapted to the screws 23. The screws 23 connect the threaded holes 49 of the rotating disk and the threaded holes 26 at the bottom end of the hollow cylinder to fix the hollow cylinder 52 on the rotating disk 22. The rotating disk 22 is located below the chassis 1 and is rotatably connected to the chassis 1 through bearings. The rotating connecting block 13, the hollow cylinder 52, the driven gear 25 and the rotating disk 22 rotate synchronously.

[0057] In this embodiment, the pin hole at the lower part of the workpiece 35 is the workpiece pin hole 42, and the pin hole at the upper end face of the base 38 is the base pin hole 44.

[0058] In this embodiment, the upper end of the boss threaded shaft 27 is integrally formed with a fixed shaft end clamping block 28, and the outer diameter of the shaft end clamping block 28 is larger than the inner diameter of the upper opening of the center hole 36 of the workpiece 35. When the boss threaded shaft 27 is screwed, the shaft end clamping block 28 can be held to apply torque. At the same time, the shaft end clamping block 28 can form an axial limit block on the upper end of the workpiece 35 to prevent the workpiece from moving upward and getting out of the fixture during the milling process.

[0059] In this embodiment, the drive motor 21 is equipped with a motor pressure sensor 50 and a motor resistance detection module 51.

[0060] In this embodiment, the axial positioning device 46 is designed with at least three booms, which are installed at circumferential intervals.

[0061] Example 2 This embodiment discloses a workpiece machining clamping method, specifically a centrifugal impeller milling clamping and positioning method, which is implemented using the workpiece machining positioning fixture described in Embodiment 1; the method includes the following steps: Step 1: Assemble the concentric positioning device 45 of the workpiece machining positioning fixture into the base 38, retract all sliders to the minimum limit stroke, place the workpiece 35 to be processed, and complete the preparation before clamping.

[0062] In step one of this embodiment, the concentric positioning device 45 is fixedly installed in the mounting groove 39 of the base 38; when the equipment is not started, all sliders and positioning pins 2 are stopped at the minimum limit retraction position of the slide rail 19, as shown in the figure. Figure 5 As shown, the centrifugal impeller to be processed is placed stably on the upper surface of the base 38, and the two are initially circumferentially positioned by the positioning pin 43, thus completing the loading and positioning of the workpiece 35.

[0063] Step 2: After the workpiece 35 is placed in place, the drive motor 21 of the concentric positioning device 45 starts, driving multiple sets of sliders to expand radially in sync. Each positioning post 2 moves radially outward in sync, pressing against the wall of the limiting hole 37 at the bottom of the workpiece 35, thus completing the concentric centering of the workpiece 35 and restricting the radial offset and circumferential rotation of the workpiece 35.

[0064] In step two of the present invention, the drive motor 21 is equipped with an electromagnetic brake and a motor pressure sensor 50. After the centrifugal impeller is placed in place, the motor pressure sensor 50 detects the change in gravity load and sends a start signal, and the drive motor 21 starts. The motor shaft of the drive motor 21 drives the active gear 20 and the driven gear 25 to mesh and transmit power, and then drives the rotating connecting block 13 to rotate around the central axis. Rotating the connecting block 13 drives each transmission rod to swing synchronously. The transmission rod is connected to the slider. The slider is slidably mounted on the slide rail 19 and, under the pushing and pulling action of the transmission rod, performs synchronous radial concentric expansion motion along the slide rail 19. Multiple positioning pins 2 are respectively assembled on the corresponding sliders, and expand outwards synchronously with the sliders, and simultaneously press against the wall of the limiting hole 37 at the bottom of the centrifugal impeller, completing the concentric centering of the centrifugal impeller, so that the inner hole center of the centrifugal impeller is completely aligned with the rotation center of the fixture. After multiple positioning pins 2 move outward synchronously and contact the wall of the limiting hole 37 of the workpiece 35, the motor resistance detection module 51 collects the working current of the drive motor 21 in real time; preset two-level current thresholds, and when the current threshold corresponding to the preset clamping force is reached, it is determined that the centering is in place; if the current exceeds the overload protection threshold, the relay instantly cuts off the power supply circuit of the drive motor 21; the built-in electromagnetic brake of the drive motor 21 synchronously loses power and locks the motor output shaft, locking the rotation position of the drive gear 20 and the driven gear 25, and continuously maintaining the radial and circumferential constraints of the positioning pins 2 on the workpiece 35 to prevent the slider from retracting and loosening during the processing.

[0065] Step 3: Insert the retracted axial positioning device 46 into the center hole 36 of the workpiece 35. The keyway 41 on the box surface engages to lock the lower sliding member 33 at the lower end of the axial positioning device 46. Rotate the threaded shaft 27 of the boss to drive the outward expansion of the moving arm to press against the wall of the center hole 36 of the workpiece 35, thereby achieving the inner hole support and limit of the workpiece 35. Figure 11 As shown.

[0066] In step three of this embodiment, after the centrifugal impeller is concentrically centered, the centrifugal impeller is axially supported and positioned using the axial positioning device 46. First, the expansion mechanism 30, which is fitted outside the boss threaded shaft 27, is adjusted to a fully retracted state. Then, the axial positioning device 46 is inserted into the center hole 36 of the centrifugal impeller. The positioning key 29 at the bottom of the expansion mechanism 30 is embedded in the box surface positioning keyway 41 on the surface of the box cover 11, which constrains the lower sliding member 33 so that it cannot slide axially. The rotating boss threaded shaft 27 forms a threaded pair transmission with the upper rotating part 34 and the boss threaded shaft 27. Under the locking action of the lower sliding part 33, the upper rotating part 34 feeds downward along the boss threaded shaft 27. The distance between the upper rotating part 34 and the lower sliding part 33 decreases, squeezing each set of upper moving arms 31 and lower moving arms 32 to swing outward around the hinge point until the connecting bent section of the upper and lower moving arms synchronously presses against the inner wall of the central hole 36 of the centrifugal impeller, forming uniform support for the central hole 36 of the centrifugal impeller.

[0067] Step 4: Continue rotating the threaded shaft 27 of the boss downwards until the expansion mechanism 30 stops. Then, tighten the lower locking nut 40 to lock all axial degrees of freedom of the workpiece 35. At the same time, the milling cutting load is shared by the connecting bent section. The workpiece 35 is now clamped. Figure 12 As shown; then restart the workpiece 35 machining process.

[0068] In step four of this embodiment, the boss threaded shaft 27 continues to rotate. The connecting bent section of the boom has abutted against the central hole 36 of the centrifugal impeller, generating resistance, and the expansion mechanism 30 no longer expands outward. The torque of continuous twisting is converted into axial feed driving force, pushing the boss threaded shaft 27 to move downward as a whole. After the boss threaded shaft 27 moves down to pass through the concentric positioning device 45 and enter the lower cavity of the base 38, the boss threaded shaft 27 is locked on the side of the base 38 with a locking nut 40, which completely restricts the up and down movement of the centrifugal impeller and completes the axial positioning. During the processing, the connecting bent section continuously presses against the inner wall of the central hole 36 of the workpiece 35. The entire axial positioning device 46 can share part of the milling cutting load, reduce processing vibration, and improve the stability of impeller milling.

[0069] In this invention, after the aforementioned two processes of concentric centering and axial expansion locking, the concentric positioning device 45 is concentrically centered with the fixture from the lower part of the workpiece 35, the axial positioning device 46 achieves axial clamping and auxiliary support from the central inner hole of the workpiece 35, and the positioning pin 43 achieves circumferential limiting; the two sets of positioning devices and the positioning pin 43 cooperate with each other to completely restrict all degrees of freedom of movement of the workpiece 35; during processing, the boom of the expansion mechanism 30 forms rigid support for the inner hole, shares the cutting impact force, reduces the vibration of the workpiece 35, and realizes rapid, high-precision and stable clamping of the centrifugal impeller. After clamping, milling can be carried out.

[0070] Step 5: After the workpiece 35 is processed, remove the clamp.

[0071] In step five of this embodiment, after the workpiece 35 is processed, the locking nut 40 inside the base 38 is loosened in the reverse direction, and the threaded shaft 27 of the boss is rotated in the reverse direction, causing the upper rotating part 34 to move upward, and each set of moving arms retracts inward to release the support on the inner hole of the workpiece 35; the drive motor 21 is controlled to rotate in the reverse direction, driving all the sliders and positioning pins 2 to retract to the minimum stroke along the slide rail 19; the processed workpiece 35 is taken out from above the fixture, the positioning pin 43 is pulled out, and the complete processing and clamping cycle is completed.

[0072] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0073] Finally, it should be noted that the above are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A workpiece machining positioning fixture, characterized in that, Includes a base, a concentric positioning device, and an axial positioning device; The base is horizontally arranged, and its upper surface has a mounting groove for assembling the concentric positioning device; the bottom of the base is provided with a cavity. The concentric positioning device is embedded in the mounting groove of the base, with the clamping working end of the concentric positioning device extending upwards; A through-hole is opened in the workpiece along the axial direction, and the lower part of the through-hole extends radially outward to form a limiting hole; the workpiece is placed horizontally on the upper end face of the base, and the clamping working end of the concentric positioning device is pressed against the wall of the limiting hole of the workpiece. The axial positioning device is arranged axially through the center hole of the workpiece; the upper outer wall of the axial positioning device is tightly fitted with the inner wall of the center hole of the workpiece to achieve matching and limiting; the lower part of the axial positioning device is connected and fixed to the concentric positioning device; the lower end of the axial positioning device is connected to the locking member provided in the cavity of the base.

2. The workpiece machining positioning fixture as described in claim 1, characterized in that, The concentric positioning device includes a housing, a slide rail, a slider, a positioning column, a rotary drive mechanism, and a transmission assembly. The box body has a hollow structure and is formed by a chassis and a box cover assembled on top of the chassis. The box cover is provided with a box surface positioning keyway that is adapted to the lower end of the axial positioning device, and a strip hole that is adapted to the movement trajectory of the positioning column. At least three slide rails are evenly spaced around the center of the chassis, with each slide rail extending in the same direction as the radial direction of the chassis. A slider is slidably mounted on a single slide rail, and the slider is fastened to the bottom end of the positioning post. The rotary drive mechanism is located at the center of the chassis, and the drive end of the rotary drive mechanism is connected to the input side of the transmission component. The transmission component has output ends that are evenly distributed along the circumference and correspond one-to-one with the number of sliders. Each output end of the transmission component is connected to the corresponding slider.

3. The workpiece machining positioning fixture as described in claim 2, characterized in that, The rotary drive mechanism employs a drive motor; the transmission assembly includes a driving gear, a driven gear, a rotating connecting block, and multiple transmission rods; the driving gear is mounted on the output end of the drive motor, and the central axis of the driving gear is coaxially and rigidly connected to the motor shaft of the drive motor; the driven gear is installed on the side of the driving gear and meshes with the driving gear for transmission; the driven gear is located on the outer circumferential surface of the hollow cylinder, the upper end face of the hollow cylinder is rigidly fixed to the center of the bottom surface of the rotating connecting block, the bottom of the hollow cylinder passes through the chassis and is fixedly connected to the rotating disk below the chassis, and the rotating disk is rotatably connected to the chassis via bearings; the outer edge of the rotating connecting block has evenly arranged connection positions corresponding to the number of sliders, and each connection position is hinged to a transmission rod, the end of the transmission rod away from the rotating connecting block being connected to the corresponding slider.

4. The workpiece machining positioning fixture as described in claim 3, characterized in that, The axial positioning device includes a boss threaded shaft and an expansion mechanism; the expansion mechanism consists of an upper rotating part, a lower sliding part, and multiple linkage arms. The upper rotating part is threadedly engaged with the boss threaded shaft, and the lower sliding part is slidably fitted onto the outer circumference of the boss threaded shaft; a positioning key is fixedly provided at the bottom end of the lower sliding part, and the positioning key is matched with the positioning keyway of the box surface opened on the upper end face of the box cover.

5. The workpiece machining positioning fixture as described in claim 4, characterized in that, A single boom consists of an upper boom and a lower boom connected by a hinge, with the connection point forming a connecting bend. The upper end of the upper boom is hinged to the outer wall of the upper rotating component, and the lower end of the lower boom is hinged to the outer wall of the lower sliding component. The connecting bend presses outward against the inner wall of the center hole of the workpiece.

6. The workpiece machining positioning fixture as described in claim 5, characterized in that, The workpiece and the upper surface of the base have corresponding pin holes.

7. The workpiece machining positioning fixture as described in any one of claims 3 to 5, characterized in that, Both the rotating connecting block and the rotating disk have through holes for the lower end of the axial positioning device to pass through.

8. The workpiece machining positioning fixture as described in claim 7, characterized in that, The lower end of the hollow cylinder is provided with threaded holes at intervals around the circumference, which are adapted to the screws. The hollow cylinder is fixed on the rotating disk by connecting the threaded holes of the rotating disk and the threaded holes of the hollow cylinder with screws. The rotating disk is located below the chassis.

9. A workpiece machining clamping method, wherein the method employs the workpiece machining positioning fixture as described in claim 5 or 6; characterized in that, The method includes the following steps: Step 1: Assemble the concentric positioning device of the workpiece machining positioning fixture into the base, retract all sliders to the minimum limit stroke, place the workpiece to be processed, and complete the preparation before clamping. Step 2: After the workpiece is placed in place, the drive motor of the concentric positioning device starts, driving multiple sets of sliders to expand radially in sync, and each positioning column moves radially outward in sync, pressing against the wall of the limiting hole at the bottom of the workpiece to complete the concentric centering of the workpiece. Step 3: Use an axial positioning device to provide axial support and positioning for the workpiece; first, adjust the expansion mechanism fitted outside the boss threaded shaft to the fully retracted state, and insert the entire axial positioning device into the center hole of the workpiece; the positioning key at the bottom of the expansion mechanism is embedded in the positioning keyway on the surface of the cover, and the lower sliding part cannot slide axially. The rotating boss threaded shaft, the upper rotating part and the boss threaded shaft form a threaded pair transmission, and the upper rotating part is locked by the lower sliding part. The upper rotating part feeds downward along the boss threaded shaft. The distance between the upper rotating part and the lower sliding part decreases, and the upper and lower moving arms are squeezed to swing outward around the hinge point until the connecting bending section of the upper and lower moving arms synchronously presses against the inner wall of the center hole of the workpiece, forming uniform support for the center hole of the workpiece. Step 4: Continue to rotate the threaded shaft of the boss downwards until the expansion mechanism stops. Then, tighten the lower locking nut to lock all axial degrees of freedom of the workpiece. At the same time, the milling cutting load is shared by the connecting bending section. The workpiece is clamped and the machining process is started. Step 5: After the workpiece is processed, remove the clamps.

10. The workpiece machining and clamping method as described in claim 9, characterized in that, The specific method for step five is as follows: loosen the locking nut inside the base cavity in the reverse direction, rotate the threaded shaft of the boss in the reverse direction to move the upper rotating part upward, and retract each set of booms inward to release the support of the workpiece's inner hole; drive the motor to rotate in the reverse direction, driving all the sliders and positioning pins to retract along the slide rail to the minimum stroke; remove the processed workpiece from above the fixture.

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