A kind of inner hole positioning expansion type clamp for numerical control milling machine

Abstract

The present application relates to the technical field of turning processing, in particular to a kind of inner hole positioning expansion type fixture for numerical control milling machine, including clamping disc, its left end is equipped with the shoulder circle for chuck clamping, clamping disc right end is fixedly connected with support, support is installed with the taper sleeve fixed by internal hexagon screw in, taper sleeve is equipped with cylindrical inner hole and 30 ° conical hole coaxially communicated in sequence from left to right in, clamping sleeve is slidably arranged in taper sleeve, clamping sleeve includes left part cylindrical section and right part clamping petal, cylindrical section is slidably matched with cylindrical inner hole, clamping petal is outer taper surface structure and is slidably matched with conical hole, and multiple axial straight grooves are formed elastic clamping piece along circumferential direction are set up.This application is realized by pulling rod left pull, synchronous realization clamping petal contraction hug tight workpiece, clamping head constraint enhancement rigidity and L-shaped press plate automatic press tightly, without manual intervention, it can be high efficiency, high precision, no deformation clamping special-shaped thin-walled bracket, improve the applicability of ordinary lathe in single-piece small batch inner hole processing.

Description

Technical Field

[0001] This invention relates to the field of turning technology, and more specifically to an internal hole positioning and tensioning fixture for CNC milling machines. Background Technology

[0002] In machining, conventional lathes are widely used for turning the inner or outer diameters of rotating parts. For workpieces with regular shapes, a three-jaw chuck or standard mandrel can be used for clamping. However, for irregularly shaped thin-walled parts such as milling machine brackets, which have asymmetrical structures, poor rigidity, and vertical inner holes to be machined, if the outer diameter is used as the clamping reference, deformation is easily caused by uneven local stress, which seriously affects the machining accuracy. Therefore, it is often necessary to design special fixtures that use elastic clamping sleeves to externally tighten the outer diameter of the workpiece to achieve reliable positioning and clamping, in order to meet the needs of single-piece and small-batch production.

[0003] However, for irregularly shaped parts with thin walls, such as milling machine brackets, existing clamping methods usually rely on multiple bolts or manual clamping plates to rigidly fix the local bosses. This not only makes it easy to cause deformation in thin-walled areas due to the difficulty in uniformly controlling the preload, but also lacks a unified rotation reference, making it difficult to ensure coaxiality during internal hole turning. At the same time, the clamping process requires repeated adjustment of multiple fasteners, and under asymmetrical working conditions, the cutting force is more likely to induce slight rotation or axial movement of the workpiece.

[0004] Therefore, how to achieve automatic centering, uniform clamping and reliable anti-rotation of irregular thin-walled brackets while avoiding deformation of the outer circle under pressure, and how to adapt to the needs of single-piece and small-batch production by simplifying the operation, has become an urgent technical problem to be solved when turning the inner hole of such parts. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the existing technology, the present invention solves the problems that the rigid clamping of existing fixtures easily leads to deformation of irregular thin-walled brackets, poor coaxiality, cumbersome operation and unreliable anti-rotation.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention provides an internal hole positioning and tensioning fixture for CNC milling machines, comprising a clamping disc with a shoulder outer circle at its left end for clamping by a chuck. A support is fixedly connected to the right end of the clamping disc, and a tapered sleeve fixed by an internal hexagon screw is installed in the support. The tapered sleeve has a cylindrical inner hole and a 30° tapered hole coaxially connected to it from left to right. The clamping sleeve is slidably disposed in the tapered sleeve. The clamping sleeve includes a left cylindrical section and a right clamping flap. The cylindrical section slides in fit with the cylindrical inner hole, and the clamping flap has an external tapered surface structure and slides in fit with the tapered hole. Multiple axial straight grooves are formed along the circumference to form an elastic clamping piece. A pull rod passes through the central hole of the clamping disc, and its right end is internally threaded to the cylindrical section. Its left end extends out of the left side of the clamping disc and is connected to an auxiliary fixing assembly driven by the pull rod. The auxiliary fixing assembly includes two clamping arms symmetrically arranged on both sides of the clamping flap, and the clamping arms pass through clearance grooves on both sides of the clamping disc.

[0007] Furthermore, the outer wall of the cylindrical section is symmetrically provided with limiting straight grooves, and positioning bolts are symmetrically installed at corresponding positions on the conical sleeve. The lower cylindrical end of the positioning bolt extends into the limiting straight groove and slides in cooperation with the limiting straight groove, which is used to limit the circumferential rotation of the clamping sleeve and allow its axial movement.

[0008] Furthermore, a bracket is fixed to the lower side of the support by bolts. The bracket has a threaded hole, and a double-ended stud is threaded into the threaded hole. An L-shaped pressure plate is slidably fitted on the double-ended stud, and a tension spring is also fitted on it. The upper end of the tension spring is fixedly connected to the bottom of the L-shaped pressure plate, and the lower end is fixedly connected to the bracket. A locking nut is threadedly connected to the double-ended stud located above the L-shaped pressure plate.

[0009] Furthermore, the clamping arm includes a V-shaped connecting rod, the middle of which is hinged to one end of the connecting arm. The left end of the pull rod is fixedly connected to a fixing sleeve by bolts. The other end of the connecting arm is hinged to one side of the fixing sleeve. A pair of symmetrically arranged fixing rods are fixedly connected to the outer circle of the shoulder on the left end of the clamping plate. A fixing seat is fixed between the two fixing rods. The left end of the pull rod passes through the fixing seat and slides with it. One end of the V-shaped connecting rod is hinged to one side of the fixing seat.

[0010] Furthermore, a slider is fixedly connected to one end of the V-shaped connecting rod near the clamping flap. A clamping head is provided on the outside of the slider, and a slide is provided on the inside of the clamping head. The slider is slidably disposed in the slide, and a compression spring is provided in the slide. The two ends of the compression spring are respectively connected to the slider and the inner wall of the slide.

[0011] Furthermore, the left end of the pull rod is provided with a square head, and several positioning holes are opened along the axial direction on the rod body. Positioning pins are threaded into the positioning holes to lock the axial position of the pull rod after it is clamped in place.

[0012] Furthermore, a diagonal rod is fixedly connected to the lower side of the fixed sleeve. The other end of the diagonal rod is hinged to one end of the support plate. The other end of the support plate extends horizontally and passes through the sliding hole opened on the bracket and clamping plate. Its end is supported on the bottom of the L-shaped pressure plate, which is used to release the L-shaped pressure plate synchronously when the pull rod is pulled.

[0013] Furthermore, a groove is provided at one end of the support plate near the L-shaped pressure plate. The groove is adapted to the outer diameter of the double-ended stud. Guide strips are fixed on both sides of the support plate. The guide strips slide in cooperation with the guide grooves provided on the inner walls of the sliding holes to ensure the smooth movement of the support plate.

[0014] Furthermore, a counterweight is fixedly installed on the upper end of the support to balance the centrifugal force when the clamp rotates at high speed.

[0015] Furthermore, when the pull rod is pulled to the left, the connecting arm moves through the fixed sleeve, which in turn drives the V-shaped connecting rod to move towards the center, so that the clamping heads on both sides simultaneously abut against the middle of the outer side of the clamping petal, and apply radial constraint force under the action of the compression spring to suppress the elastic deformation of the clamping petal during the contraction and clamping process. At the same time, the inclined rod on the lower side of the fixed sleeve pulls the support plate to move to the left, so that the support plate is disengaged from the bottom of the L-shaped pressure plate. The L-shaped pressure plate resets downward under the elastic force of the tension spring, pressing the non-processed area of ​​the workpiece.

[0016] Beneficial effects 1. This invention achieves uniform radial clamping and reliable axial constraint of the milling machine bracket simultaneously through a single operation of pulling the pull rod to the left. The pull rod drives the clamping sleeve to move to the left along the inner hole of the tapered sleeve, and the 30° tapered surface fit causes the elastic clamping petals to contract radially, thereby uniformly clamping the outer circle of the workpiece from the outside. This avoids local stress concentration and achieves high coaxiality centering, effectively preventing deformation of thin-walled irregular parts due to rigid clamping. At the same time, the pull rod drives the V-shaped linkage mechanism in the auxiliary fixing component, so that the clamping heads on both sides simultaneously abut against the middle of the outer side of the clamping petals, applying flexible radial constraint to suppress elastic deformation and improve the rigidity of the clamping system. This design requires no additional adjustment steps and is particularly suitable for irregularly shaped thin-walled parts that cannot be clamped by traditional chucks. It enables high-precision turning of the vertical inner hole of the milling machine bracket to be completed efficiently on ordinary lathes, expanding the process adaptability of general-purpose equipment in single-piece and small-batch production.

[0017] 2. During the leftward movement of the pull rod, the inclined rod connected to its lower part synchronously pulls the support plate to move horizontally, causing the end of the support plate to detach from the bottom of the L-shaped pressure plate. Then, when the pull rod completes the inner hole tensioning, the L-shaped pressure plate automatically resets under the action of the spring and presses the workpiece, forming a double insurance. This timing control mechanism does not require manual intervention or additional locking action, cleverly solving the cumbersome process of traditional pressure plates requiring the workpiece to be loaded first and then manually pressed. It is especially suitable for scenarios with frequent assembly and disassembly in single-piece and small-batch production. This structure not only improves clamping efficiency but also ensures the consistency of the clamping force each time, effectively preventing processing movement caused by the pressure plate not being in place. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is one of the three-dimensional structural schematic diagrams of the present invention; Figure 2 This is a second schematic diagram of the overall three-dimensional structure of the present invention; Figure 3 This is a schematic diagram of the support installation state of the present invention; Figure 4 For the present invention Figure 3 A structural breakdown diagram; Figure 5 For the present invention Figure 4 A schematic diagram of the structure at point A; Figure 6 For the present invention Figure 3 Structural sectional view; Figure 7 This is a cross-sectional schematic diagram of the conical sleeve structure of the present invention; Figure 8 This is a schematic diagram of the installation state of the fixed auxiliary component of the present invention; Figure 9 This is a schematic diagram of the fixing auxiliary component of the present invention; Figure 10 This is a cross-sectional schematic diagram of the clamping head structure of the present invention.

[0020] Reference numerals: 1. Clamping disc; 11. Shoulder outer circle; 12. Clearance groove; 13. Sliding hole; 14. Guide groove; 2. Support; 21. Counterweight; 22. Positioning bolt; 3. Conical sleeve; 4. Cylindrical section; 41. Clamping flap; 42. Limiting straight groove; 5. Pull rod; 51. Positioning hole; 52. Positioning pin; 6. Bracket; 61. Double-ended stud; 62. L-shaped pressure plate; 63. Tension spring; 64. Locking nut; 7. Fixed seat; 71. Fixed rod; 72. V-shaped connecting rod; 73. Connecting arm; 74. Fixed sleeve; 75. Slider; 76. Clamping head; 77. Compression spring; 8. Diagonal bar; 81. Support plate; 82. Guide bar. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] The present invention will be further described below with reference to embodiments.

[0023] See attached document Figure 1-10 An internal hole positioning and tensioning fixture for CNC milling machines is a special tooling adapted for turning vertical internal holes of irregular thin-walled milling machine brackets. After overall assembly, it is installed and fixed on the lathe chuck. The lathe chuck is equipped with a large through hole, which can fully accommodate the tie rod 5, auxiliary fixing components and other structures inside the fixture. It can meet the axial reciprocating sliding and hinge opening and closing motion requirements of each component. There is no structural interference throughout the process, ensuring smooth operation and precise and stable movement of the fixture.

[0024] The fixture includes a clamping plate 1, which and the support 2 form an integral assembly base. All other functional components are assembled and fixed on the base in a modular manner, and are easy to disassemble, inspect, and maintain.

[0025] like Figure 2 As shown, the left end of the clamping plate 1 is provided with a shoulder outer circle 11. After the fixture is assembled, the shoulder outer circle 11 at the left end of the clamping plate 1 is installed into the lathe chuck. A dial indicator is used to calibrate the coaxiality between the shoulder surface and the outer circle of the clamping plate 1. After the calibration is correct, the lathe chuck is locked to achieve precise coaxial fixation of the fixture and the lathe spindle. The clamping plate 1 is provided with symmetrical clearance grooves 12 on both sides for the clamping arm structure of the auxiliary fixing component to extend through.

[0026] During assembly, the clamping plate 1 and the support 2 are first assembled together. The support 2 is precisely fitted onto the assembly reference surface on the right end face of the clamping plate 1. The support 2 is then fastened to the right end of the clamping plate 1 using four sets of large hexagonal bolts and corresponding large flat washers. At the same time, two conical pins are embedded in the positioning conical holes of the support 2 and the clamping plate 1 to achieve precise alignment and positioning. Through the high-precision positioning of the conical pins, the coaxiality of the assembly of the support 2 and the clamping plate 1 can be strictly guaranteed, effectively avoiding the machining eccentricity problem caused by assembly offset, greatly improving the overall assembly stability of the fixture, and providing a structural foundation for subsequent high-precision machining.

[0027] After the base assembly is completed, the tapered sleeve 3 is fixed and assembled. The tapered sleeve 3 is aligned with the smooth through hole on the right end face of the support 2 and inserted into the mounting. The assembly method of clearance fit is adopted to effectively ensure the coaxiality of the tapered sleeve 3. After the tapered sleeve 3 is assembled in place, it is locked and fixed in the threaded blind hole on the end face of the support 2 by four small internal hex screws, so as to achieve a stable connection between the tapered sleeve 3 and the support 2 without loosening.

[0028] The conical sleeve 3 has a cylindrical inner hole and a 30° conical hole arranged coaxially inside. The holes are arranged coaxially and connected, which can provide a precise structural reference for the subsequent axial sliding guidance and conical extrusion clamping operation of the clamping sleeve.

[0029] This invention relies on a clamping sleeve to achieve workpiece positioning. The clamping sleeve is made entirely of spring steel, possessing excellent elastic deformation capability, structural strength, and fatigue resistance. It can repeatedly perform elastic contraction and reset actions over a long period of time, is not prone to plastic deformation, and has a long service life. (Reference) Figure 6 and Figure 7 The clamping sleeve includes a cylindrical section 4 on the left and a clamping flap 41 on the right. The outer circle of the cylindrical section 4 slides precisely with the inner cylindrical hole of the conical sleeve 3, which can ensure that the axial linear movement of the clamping sleeve is smooth and without jamming. The outer side of the clamping flap 41 is provided with a 30° tapered outer circle, which slides and squeezes with the 30° tapered hole inside the conical sleeve 3, together forming the core structure of the conical clamping.

[0030] refer to Figure 7 A limiting straight groove 42 is provided on the upper part of the outer circle of the cylindrical section 4. The corresponding position of the tapered sleeve 3 is equipped with a positioning bolt 22. The lower cylindrical end of the positioning bolt 22 extends into the limiting straight groove 42 and forms a sliding fit. This structure can strictly limit the circumferential rotational freedom of the clamping sleeve as a whole, completely eliminate the rotational deviation of the clamping sleeve during operation, and at the same time, it does not restrict the axial left and right movement of the clamping sleeve, ensuring that the clamping sleeve can only make precise linear movements along the axial direction. From the structural source, it ensures the workpiece clamping and positioning accuracy and avoids workpiece processing deviation caused by the rotation of the clamping sleeve.

[0031] Four symmetrically distributed axial straight grooves are evenly opened along the circumference of the clamping petal 41, so that the clamping petal 41 forms four independent and symmetrical elastic clamping plate structures, which can uniformly and synchronously complete the elastic contraction and expansion actions.

[0032] refer to Figure 7 The cylindrical section 4 has a threaded inner hole at the center of the left end, which is locked to the external thread at the right end of the pull rod 5, realizing the integrated structure after the pull rod 5 is connected to the clamping sleeve. The left end of the pull rod 5 is milled into a square head structure, which is convenient for manual or tool clamping and driving, making the operation convenient and labor-saving.

[0033] Meanwhile, the tie rod 5 has multiple sets of positioning holes 51 along its axial direction, such as Figure 8 As shown, a positioning pin 52 can be threaded into the positioning hole 51. After the workpiece is clamped in place, the axial position of the pull rod 5 is locked by the positioning pin 52, which completely avoids the problem of the pull rod 5 loosening and the workpiece loosening due to processing vibration, and improves processing stability.

[0034] When actually clamping the workpiece, the irregular thin-walled milling machine bracket to be processed is placed in the positioning position of the inner hole of the clamping sleeve. The pull rod 5 is manually driven to move axially to the left, and the cylindrical section 4 and the clamping petal 41 are simultaneously pulled to slide to the left along the inner hole of the tapered sleeve 3. At this time, the outer 30° tapered outer circle of the clamping petal 41 and the 30° tapered hole of the tapered sleeve 3 are squeezed against each other. The four sets of elastic clamping plates are squeezed inward synchronously by the uniform tapered surface pressure, and uniformly hug the outer circle surface of the milling machine bracket from the outside, realizing high coaxiality and stress concentration-free centering clamping. Compared with the traditional clamping method, this structure solves the industry problems of deformation, breakage and insecure clamping of thin-walled irregular workpieces, and accurately adapts to the small batch and high precision inner hole turning needs of the milling machine bracket.

[0035] To further improve the clamping stability of workpieces during high-speed rotational machining and prevent slight displacement or vibration caused by cutting forces or centrifugal effects, such as Figure 3 and Figure 4 As shown, the bracket 6 is fixedly installed on the bottom surface of the support 2 by two large internal hexagon screws. The right end of the bracket 6 has a vertical threaded inner hole. The lower end of the double-ended stud 61 is screwed into the threaded hole and locked to achieve reliable positioning. Both ends of the double-ended stud 61 have external threads.

[0036] The double-ended stud 61 is fitted with a tension spring 63, an L-shaped pressure plate 62, an extra-large flat washer, and a locking nut 64 in sequence from bottom to top on its outer side. The L-shaped pressure plate 62 is slidably fitted onto the double-ended stud 61 through its inner hole, allowing it to slide smoothly in the vertical direction. At the same time, the L-shaped pressure plate 62 can rotate horizontally around the axis of the double-ended stud 61. When no workpiece is clamped, its horizontal section rotates inward to avoid the workpiece installation path and prevents it from obstructing the smooth insertion of the milling machine bracket into the clamping sleeve. After the workpiece is in place, the L-shaped pressure plate 62 rotates to the top of the workpiece above the non-machined area with a slight push from the operator, for subsequent fixation of the workpiece. The upper end of the tension spring 63 is fixedly connected to the bottom of the L-shaped pressure plate 62, and the lower end is fixedly connected to the top surface of the bracket 6. Under normal conditions, it is in a pre-stretched state, providing a stable automatic reset force for the L-shaped pressure plate 62, ensuring that the L-shaped pressure plate 62 can reliably press down on the workpiece after each clamping.

[0037] The tension spring 63 is made of high fatigue strength stainless steel, which has excellent durability and anti-relaxation performance. It can withstand tens of thousands of compression and rebound cycles without significant loss of elasticity, making it suitable for the production needs of single-piece, small-batch, and frequent assembly and disassembly. At the same time, its two ends adopt a hook or slot connection structure, which facilitates quick disassembly and replacement when the spring ages or is damaged, improving the maintainability and service life of the fixture.

[0038] like Figure 1 As shown, a counterweight 21 is fixedly installed on the upper end face of the support 2 using three small hexagonal bolts and small flat washers. The counterweight 21 is the core balancing component for high-speed rotation machining of the fixture. During lathe machining, the fixture rotates at high speed with the lathe spindle. The counterweight 21 can accurately counteract the centrifugal force generated by the eccentricity of the fixture structure and the asymmetry of the workpiece clamping, effectively suppressing the vibration and swaying of the fixture during high-speed rotation, ensuring the coaxiality and running stability of the fixture rotation, avoiding the problems of inner hole roundness error and surface roughness deviation caused by vibration, and improving the workpiece machining quality.

[0039] like Figure 8 and Figure 9 As shown, the auxiliary fixing assembly includes two sets of symmetrically arranged clamping arm structures. The clamping arm is mainly composed of a V-shaped connecting rod 72, a connecting arm 73, a fixing sleeve 74, a slider 75, a clamping head 76, and a compression spring 77. The left end of the clamping plate 1 is fixedly provided with symmetrically arranged fixing rods 71. A fixing seat 7 is fixedly installed between the two fixing rods 71. The left end of the pull rod 5 passes through the fixing seat 7 and slides with it to ensure that the axial movement of the pull rod 5 is stable.

[0040] The left end of the pull rod 5 is fixedly connected to the fixing sleeve 74 by bolts. Connecting arms 73 are hinged to both sides of the fixing sleeve 74. The other end of the connecting arm 73 is hinged to the middle of the V-shaped connecting rod 72. One end of the V-shaped connecting rod 72 is hinged to the side of the fixing seat 7, and the other end is fixedly fitted with a slider 75. Figure 10As shown, the slider 75 is slidably assembled in the slide rail opened inside the clamping head 76. The slide rail is equipped with a compression spring 77, the two ends of which abut against the end face of the slider 75 and the inner wall of the slide rail, respectively, to provide flexible buffering and adaptive fitting force during clamping.

[0041] To ensure long-term reliability, the compression spring 77 is made of stainless steel with a high elastic limit. After heat treatment, it has excellent fatigue resistance and can maintain stable elastic force under tens of thousands of high-frequency clamping cycles. It is not easy to undergo permanent deformation or loosening, thus ensuring the consistency of clamping force and the life of the clamp.

[0042] Secondly, to prevent the slider 75 from detaching from the slide rail during movement, an inwardly extending limiting shoulder is provided at the entrance of the slide rail. The outer contour dimension of the slider 75 is slightly larger than the opening of the shoulder, so that it can only slide along the axial direction of the slide rail and cannot detach axially. At the same time, guide bosses can be provided on both sides of the slider 75 to cooperate with the corresponding grooves on the inner wall of the slide rail, further limiting its radial sway and ensuring smooth movement.

[0043] During the process of the pull rod 5 moving to the left to clamp the workpiece, the fixed sleeve 74 is pulled to the left synchronously with the pull rod 5, which drives the connecting arms 73 on both sides and the V-shaped connecting rod 72 to swing and retract synchronously, so that the clamping heads 76 on both sides move towards the center synchronously and abut against the middle of the outer side of the clamping petal 41, applying a uniform radial constraint force to the elastic clamping petal 41. This can effectively suppress the problem of excessive elastic deformation and unilateral displacement of the clamping petal 41, ensuring that the contraction amplitude of the four sets of clamping petals 41 is uniform and the workpiece is subjected to symmetrical force, further improving the workpiece clamping accuracy and force stability. The compression spring 77 can provide elastic buffer preload during the clamping process to avoid structural damage caused by rigid clamping, while ensuring tight clamping.

[0044] Furthermore, such as Figure 5 and Figure 8 As shown, the lower side of the fixed sleeve 74 is fixedly connected to the inclined rod 8, and the other end of the inclined rod 8 is hinged to the support plate 81. The clamping plate 1 and the bracket 6 are respectively provided with sliding holes 13. The support plate 81 is horizontally installed through the sliding hole 13. Guide strips 82 are fixedly installed on both sides of the support plate 81. Guide grooves 14 are opened on the inner walls of both sides of the sliding hole 13. The guide strips 82 and the guide grooves 14 slide in cooperation to ensure that the support plate 81 slides smoothly without deviation.

[0045] Under normal conditions, the end of the support plate 81 is supported at the bottom of the L-shaped pressure plate 62, providing limiting support for the L-shaped pressure plate 62. At this time, the L-shaped pressure plate 62 is located at the upper end of the double-ended stud 61 and is in a state of tensioning the tension spring 63. When the pull rod 5 pulls to the left to clamp the workpiece, the inclined rod 8 moves to the left synchronously with the fixing sleeve 74, pulling the support plate 81 to slide to the left along the guide groove 14, causing the end of the support plate 81 to disengage from the bottom support of the L-shaped pressure plate 62. After the L-shaped pressure plate 62 loses its support, it can automatically reset under the action of the tension spring 63. Release, realize the synchronous release of the auxiliary clamping structure, so that the main clamping action and the auxiliary clamping action are coordinated and matched. Of course, in order to enhance the fixing effect, the locking nut 64 at the upper end of the double-headed stud 61 can also be rotated to squeeze the extra-large flat washer and L-shaped pressure plate 62 downward, overcome the elastic force of the tension spring 63 and continue to push the L-shaped pressure plate 62 downward, so that the L-shaped pressure plate 62 tightly presses the non-machined area of ​​the milling machine bracket, realizes the secondary positioning and clamping of the workpiece, and eliminates the problems of loosening, axial movement, vibration and displacement of the workpiece during the machining process.

[0046] After the workpiece is processed, the locating pin 52 is removed, and the L-shaped pressure plate 62 is rotated inward to avoid the workpiece contour. It is then slid upward along the double-headed stud 61 to the high position. Then, the pull rod 5 is pushed in the opposite direction to move to the right axial direction, which simultaneously drives the clamping sleeve to slide to the right along the inner hole of the tapered sleeve 3. When the 30° tapered outer circle of the clamping petal 41 gradually gets away from the squeezing constraint of the 30° tapered hole inside the tapered sleeve 3, the four sets of elastic clamping plates automatically and evenly expand due to the elastic recovery performance of the spring steel material itself, and quickly release the clamping state on the inner hole of the milling machine bracket. At the same time, the pull rod 5 moves to the right, causing the fixed sleeve 74 to move to the right in sync. Through the connecting arms 73 on both sides, the V-shaped connecting rod 72 is driven to swing outward, so that the clamping heads 76 on both sides move away from the outside of the clamping petal 41 in sync, releasing the radial constraint on the clamping petal 41. The slider 75 retracts to the initial position in the slide under the action of the compression spring 77, assisting the overall reset of the fixing assembly.

[0047] At the same time, the inclined rod 8 on the lower side of the fixed sleeve 74 moves to the right and pushes the support plate 81 to slide to the right along the guide groove 14, so that the end of the support plate 81 moves back to the bottom of the L-shaped pressure plate 62, restoring its supporting and limiting function, and preparing for the next clamping cycle.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A kind of inner hole positioning tension type clamp for numerical control milling machine, including chucking disc (1), its left end is equipped with the shoulder circle (11) for being clamped by chuck, it is characterized in that, The clamping disc (1) is fixedly connected to a support (2) at the right end. A conical sleeve (3) is installed in the support (2) and fixed by an internal hexagon screw. The conical sleeve (3) is provided with a cylindrical inner hole and a 30° conical hole coaxially connected to it from left to right. The clamping sleeve is slidably disposed in the conical sleeve (3). The clamping sleeve includes a left cylindrical section (4) and a right clamping flap (41). The cylindrical section (4) is slidably engaged with the cylindrical inner hole. The clamping flap (41) is an external conical surface structure and is slidably engaged with the conical hole. Multiple axial straight grooves are opened along the circumference to form an elastic clamping piece. The pull rod (5) passes through the center hole of the clamping disc (1). Its right end is internally threaded to the cylindrical section (4). Its left end extends out of the left side of the clamping disc (1) and is connected to an auxiliary fixing component driven by the pull rod (5). The auxiliary fixing component includes two clamping arms symmetrically arranged on both sides of the clamping flap (41). The clamping arms pass through the clearance grooves (12) on both sides of the clamping disc (1).

2. The internal hole positioning and tensioning fixture for a CNC milling machine according to claim 1, characterized in that, The outer wall of the cylindrical section (4) is symmetrically provided with a limiting straight groove (42), and a positioning bolt (22) is symmetrically installed on the corresponding position on the conical sleeve (3). The lower cylindrical end of the positioning bolt (22) extends into the limiting straight groove (42) and slides with the limiting straight groove (42) to limit the circumferential rotation of the clamping sleeve and allow its axial movement.

3. The internal hole positioning and tensioning fixture for a CNC milling machine according to claim 2, characterized in that, The support (2) is fixed to the underside of the bracket (6) by bolts. The bracket (6) has a threaded hole, and a double-ended stud (61) is threaded inside the threaded hole. An L-shaped pressure plate (62) is slidably sleeved on the double-ended stud (61), and a tension spring (63) is also sleeved on it. The upper end of the tension spring (63) is fixedly connected to the bottom of the L-shaped pressure plate (62), and the lower end is fixedly connected to the bracket (6). A locking nut (64) is threadedly connected to the double-ended stud (61) above the L-shaped pressure plate (62).

4. The internal hole positioning and tensioning fixture for a CNC milling machine according to claim 1, characterized in that, The clamping arm includes a V-shaped connecting rod (72), the middle part of which is hinged to one end of the connecting arm (73). The left end of the pull rod (5) is fixedly connected to a fixing sleeve (74) by bolts. The other end of the connecting arm (73) is hinged to one side of the fixing sleeve (74). A pair of symmetrically arranged fixing rods (71) are fixedly connected to the outer circle (11) of the shoulder at the left end of the clamping plate (1). A fixing seat (7) is fixed between the two fixing rods (71). The left end of the pull rod (5) passes through the fixing seat (7) and slides with it. One end of the V-shaped connecting rod (72) is hinged to one side of the fixing seat (7).

5. A hole positioning and tensioning fixture for a CNC milling machine according to claim 4, characterized in that, The V-shaped connecting rod (72) is fixedly connected to a slider (75) at one end near the clamping flap (41). A clamping head (76) is provided on the outside of the slider (75), and a slide is provided on the inside of the clamping head (76). The slider (75) is slidably disposed in the slide, and a compression spring (77) is provided in the slide. The two ends of the compression spring (77) are respectively connected to the slider (75) and the inner wall of the slide.

6. A hole positioning and tensioning fixture for a CNC milling machine according to claim 5, characterized in that, The pull rod (5) has a square head on the left end, and several positioning holes (51) are opened along the axial direction on the rod body. Positioning pins (52) are threaded into the positioning holes (51) to lock the axial position of the pull rod (5) after it is clamped in place.

7. A hole positioning and tensioning fixture for a CNC milling machine according to claim 6, characterized in that, The lower side of the fixed sleeve (74) is fixedly connected to a diagonal rod (8). The other end of the diagonal rod (8) is hinged to one end of the support plate (81). The other end of the support plate (81) extends horizontally and passes through the sliding hole (13) opened on the bracket (6) and clamping plate (1). Its end is supported on the bottom of the L-shaped pressure plate (62) for synchronously releasing the L-shaped pressure plate (62) when the pull rod (5) is pulled.

8. A hole positioning and tensioning fixture for a CNC milling machine according to claim 7, characterized in that, The support plate (81) has a groove at one end near the L-shaped pressure plate (62). The groove is adapted to the outer diameter of the double-headed stud (61). Guide strips (82) are fixed on both sides of the support plate (81). The guide strips (82) slide with the guide grooves (14) on the inner walls of the sliding hole (13) to ensure the smooth movement of the support plate (81).

9. A hole positioning and tensioning fixture for a CNC milling machine according to claim 1, characterized in that, A counterweight (21) is fixedly installed on the upper end of the support (2) to balance the centrifugal force when the clamp rotates at high speed.

10. A hole positioning and tensioning fixture for a CNC milling machine according to claim 8, characterized in that, When the pull rod (5) is pulled to the left, the connecting arm (73) is driven to move through the fixed sleeve (74), which in turn drives the V-shaped connecting rod (72) to move closer to the center, so that the clamping heads (76) on both sides simultaneously abut against the middle of the outer side of the clamping petal (41), and apply radial constraint force under the action of the compression spring (77) to suppress the elastic deformation of the clamping petal (41) during the contraction and clamping process. At the same time, the inclined rod (8) on the lower side of the fixed sleeve (74) pulls the support plate (81) to move to the left, so that the support plate (81) is separated from the bottom of the L-shaped pressure plate (62), and the L-shaped pressure plate (62) resets downward under the elastic force of the tension spring (63) to press the non-processed area of ​​the workpiece.

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