Inner supporting and clamping assembly for clamping and machining small-hole workpiece

Abstract

An inner supporting and clamping assembly for clamping and machining a small-hole workpiece comprises an auxiliary main shaft, and a containing cavity is formed in the auxiliary main shaft; the inner supporting chuck is connected to the front end of the auxiliary main shaft and sequentially comprises a deformation section, a transition section and a limiting section in the axial direction, the deformation section, the transition section and the limiting section are sequentially and coaxially connected in a step shape, the inner supporting chuck is integrally formed and is provided with at least three main grooves formed in the radial direction, and the main grooves extend in the radial direction from the center position of the limiting section; the transition section is used for guiding deformation to be concentrated on the deformation section; the ejector rod is arranged in the containing cavity of the auxiliary main shaft in a sliding mode, and the front end of the ejector rod is a plane and selectively makes contact with the center of the end face of the limiting section so as to transmit axial pressure to the inner supporting chuck. According to the embodiment of the invention, uniform contact can be formed in the clamping process, so that the inner wall of the inner supporting chuck is prevented from being pressed in a penetrating manner, and the service life of the inner supporting chuck is effectively prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of processing fixtures, and particularly relates to an internal support clamping assembly for clamping and processing small-hole workpieces. Background Art

[0002] With the development of precision machining technology, internal support chucks are widely used due to their characteristics suitable for internal hole positioning and clamping. In equipment such as sliding headstock lathes and CNC lathes, the internal support chuck can be tightened from the inside of the workpiece to achieve stable clamping and positioning, avoiding problems such as workpiece deformation and eccentricity that may be caused by traditional external clamping methods.

[0003] However, when the existing internal support chucks are applied to small-diameter internal hole parts, they have the following disadvantages: 1. The opening structure of the traditional internal support chuck is not detailed enough, and its expansion amount is difficult to accurately control within a small size range, and it is extremely easy to cause damage to the internal hole of the part due to excessive expansion, affecting the quality of the finished product; 2. The traditional internal support chuck uses a tip piercing method during the clamping process, which will cause concentrated contact pressure and increased wear, thus greatly reducing the service life; 3. In addition, the deformation area of the traditional internal support chuck is mostly a whole-section structure, with dispersed forces, and it is difficult to achieve directional elastic deformation control, resulting in poor stability and consistency; Therefore, designing an internal support chuck with the ability of micro progressive opening control and suitable for small-hole precision workpieces has become a key requirement in current machining clamping technology. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an internal support clamping assembly for clamping and processing small-hole workpieces in view of the deficiencies of the prior art, so as to overcome the limitations in durability and precision of the existing elastic materials and thin-film circuits in the traditional internal support clamping assembly for clamping and processing small-hole workpieces.

[0005] The purpose of the present invention is to provide an internal support clamping assembly for clamping and processing small-hole workpieces in view of the defects and deficiencies of the prior art, including: A sub-spindle, which is internally provided with a receiving cavity; An internal support chuck, connected to the front end of the sub-spindle, and sequentially including a deformation section, a transition section, and a limiting section along the axial direction. The deformation section, the transition section, and the limiting section are coaxially connected in a stepped manner. The internal support chuck is integrally formed. The internal support chuck is provided with at least three main grooves arranged radially. The main grooves extend radially from the central position of the limiting section, sequentially passing through the transition section and the deformation section. The transition section is used to guide the deformation to concentrate on the deformation section; A push rod, slidably arranged in the receiving cavity of the sub-spindle. The front end of the push rod is a flat surface and can selectively contact the center of the end face of the limiting section to transmit axial pressure to the internal support chuck.

[0006] Furthermore, a plurality of auxiliary notches arranged radially are further provided on the limiting section.

[0007] Furthermore, a first through hole is further provided at one end of the auxiliary notch away from the deformation section.

[0008] Furthermore, a plurality of second through holes evenly distributed in the circumferential direction are further provided on the limiting section for balancing the force distribution of the limiting section.

[0009] Furthermore, the deformation section at least includes a first deformation part and a second deformation part, the first deformation part and the second deformation part are coaxially connected in a stepped manner in sequence, and the outer diameter of the first deformation part is smaller than the outer diameter of the second deformation part.

[0010] Furthermore, the first deformation part and the second deformation part are connected by an arc structure in a transitional manner and are integrally formed with the inner support chuck.

[0011] Furthermore, a limiting part is provided in the accommodating cavity, and the sub-spindle restricts the sliding range of the ejector rod through the limiting part; Furthermore, one end of the stroke rod is connected to the stroke control device and can slide towards the inner support chuck under the drive of the stroke control device, and the other end of the stroke rod is in contact and cooperation with the ejector rod for transmitting the axial driving force to the ejector rod.

[0012] Furthermore, the stroke control device includes an adjusting nut screwed to the tail of the sub-spindle, a support sleeve sleeved on the tail of the sub-spindle, and a plurality of pawls rotatably connected to the support sleeve; The pawl further includes a fixed end and a free end. A plurality of rotation shaft installation positions are arranged at intervals in the circumferential direction on the outer periphery of the support sleeve. The fixed end is rotatably arranged at the corresponding rotation shaft installation position. The end face of the adjusting nut has a pressing surface for contacting and pushing each pawl. The pawl deflects around the fixed end under the rotation drive of the adjusting nut, and the free end of each pawl selectively contacts the tail of the stroke rod; wherein, When the pawl deflects, the free end pushes the stroke rod to slide axially along the sub-spindle forward.

[0013] Furthermore, a limiting device is further provided between the sub-spindle and the ejector rod, and the limiting device is used for restricting the axial movement and circumferential rotation of the ejector rod in the sub-spindle.

[0014] Furthermore, the limiting device includes a third through hole provided on the side wall of the sub-spindle, a positioning pin screwed in the third through hole, and a sliding groove provided on the outer surface of the ejector rod. The end of the positioning pin extends into the sliding groove to limit the axial stroke or circumferential rotation of the ejector rod.

[0015] In the embodiment of the present invention, by arranging a plurality of main grooves in the inner support chuck that extend radially from the center of the restriction section and penetrate to the deformation section, the chuck can achieve that the opening action is concentrated in the front center area when loaded by the ejector rod, thereby realizing precise control of the expansion deformation path and avoiding clamping instability caused by force concentration or deformation diffusion. At the same time, the front end of the ejector rod is set as a flat structure. Compared with the traditional pointed loading form, it can form uniform contact during the clamping process, avoid piercing and pressing damage to the inner wall of the inner support chuck, and effectively extend the service life of the inner support chuck. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 is one of the existing inner support chucks; Figure 2 is a cross-sectional view of the existing inner support chuck; Figure 3 is a cross-sectional view of the embodiment of the present invention; Figure 4 is Figure 3 an enlarged view of part A of Figure 5 is a schematic structural diagram of the embodiment of the present invention; Figure 6 is Figure 5 an enlarged view of part B of Figure 7 is a front view of the embodiment of the present invention; Figure 8 is a schematic structural diagram of the inner support chuck of the embodiment of the present invention; Figure 9 is a schematic structural diagram of another perspective of the embodiment of the present invention; Figure 10 is Figure 9 an enlarged view of part C of Figure 11 is a schematic diagram of the dimensions of the inner support chuck and the workpiece in the embodiment of the present invention.

[0018] Reference numerals: 1. Sub-spindle; 11. Accommodation cavity; 12. Limiting part; 2. Inner support chuck; 21. Deformation section; 211. First deformation part; 212. Second deformation part; 22. Transition section; 23. Limiting section; 231. Second through hole; 232. Main groove; 233. Auxiliary notch; 2331. First through hole; 3. Ejector rod; 4. Position limiting device; 41. Third through hole; 42. Positioning pin; 43. Slide groove; 5. Stroke rod; 6. Stroke control device; 61. Adjusting nut; 62. Support sleeve; 63. Pawl; 631. Fixed end; 632. Free end; 7. Inner support nut; 71. Inner support screw; 8. Slide sleeve; 9. Workpiece. Specific implementation mode

[0019] The present invention will be further described in detail below with reference to the accompanying drawings.

[0020] This specific embodiment is only an interpretation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as they are within the scope of the claims of the present invention, they are protected by the Patent Law.

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. Refer to Figure 1 - Figure 2 , in the prior art, in the field of precision machining, the clamping demand for small-hole workpieces 9 is increasing day by day. The traditional inner support chuck has problems such as insufficient control accuracy of the expansion amount and uneven contact pressure distribution. When applied to workpieces 9 with a smaller inner diameter, it is difficult for a rigid structure to achieve micro-deformation adjustment, and it is easy to cause damage to the hole wall. At the same time, a single deformation area leads to stress concentration, affecting the clamping stability and service life. For example, when machining a micro-bearing race, the traditional chuck often causes surface indentations or elliptical deformation of the workpiece 9 because it cannot evenly disperse the contact force.

[0022] To solve the above problems, the applicant found that the key defect of the existing clamping device lies in the lack of sub-region control ability in the deformation structure, resulting in the inability to concentrate elastic deformation directionally. By analyzing the deformation transfer path, it is proposed to divide the chuck into different functional segments to guide the stress distribution: First, an axial stepped structure needs to be constructed to achieve the directional compression of the deformation segment 21; second, a through main groove 232 is set to enable the chuck to have a controllable radial expansion ability; finally, the axial pressure conduction mechanism is formed by the contact between the ejector rod 3 and the end face of the chuck. This idea effectively solves the contradiction between the dispersed deformation and excessive contact pressure of the traditional structure.

[0023] Therefore, referring to Figure 2 - Figure 10 , an internal support clamping assembly for clamping and machining small-hole workpieces is provided in an embodiment of the present invention, including a sub-spindle 1, an internal support chuck 2, and an ejector rod 3. Among them, a receiving cavity 11 is provided inside the sub-spindle 1; the internal support chuck 2 is connected to the front end of the sub-spindle 1 and sequentially includes a deformation segment 21, a transition segment 22, and a limiting segment 23 along the axial direction. The deformation segment 21, the transition segment 22, and the limiting segment 23 are coaxially connected in a stepped manner in sequence. The internal support chuck 2 is integrally formed. The internal support chuck 2 is provided with at least three main grooves 232 arranged radially. The main grooves 232 radially extend from the central position of the limiting segment 23 and sequentially penetrate through the transition segment 22 and the deformation segment 21. The transition segment 22 is used to guide the deformation to concentrate on the deformation segment 21; the ejector rod 3 is slidably arranged in the receiving cavity 11, and the front end plane thereof can selectively contact the center of the end face of the limiting segment 23 to transmit the axial pressure.

[0024] It should be noted that the sub-spindle 1 refers to the power transmission component that bears the clamping assembly, and can be specifically realized by a hollow cylindrical structure. The internal receiving cavity 11 thereof is used to install the moving assembly of the ejector rod 3. The deformation segment 21 of the internal support chuck 2 refers to the area that generates radial elastic deformation; the transition segment 22 refers to the intermediate area connecting the deformation segment 21 and the limiting segment 23, which is used to convert the axial pressure transmitted by the ejector rod 3 into the radial expansion force of the deformation segment 21; the limiting segment 23 refers to the fixed end 631 that restricts the excessive deformation of the chuck, and the center of its end face contacts the ejector rod 3 to form a pressure transmission interface; the main groove 232 refers to a through groove radially opened along the center of the internal support chuck 2, and can be specifically set as a straight groove or a spiral groove distributed at equal angles, and the elastic deformation amount of the chuck is adjusted by controlling the groove width and depth.

[0025] Specifically, when the inner support chuck 2 is working, the ejector rod 3 is driven to move axially along the sub-spindle 1. When the front-end plane of the ejector rod 3 contacts the center of the end face of the limiting section 23, the axial pressure generated is transmitted to the deformation section 21 through the stepped structure. The transition section 22 converts part of the axial pressure into radial expansion force, guiding the deformation section 21 to generate uniform radial expansion. The existence of the main groove 232 enables the inner support chuck 2 to form multiple independent elastic arms, and each arm expands outward synchronously under pressure, realizing uniform support for the inner hole of the workpiece 9. Since the elastic deformation of the deformation section 21 is restricted by the geometric shape of the transition section 22, its expansion amount can be precisely controlled within a very small range, avoiding the over-positioning problem caused by the overall expansion of traditional chucks.

[0026] Compared with the prior art, the traditional inner support chuck adopts a single-section deformation structure, and the deformation area lacks gradient control, resulting in difficult precise adjustment of the expansion amount. The stepped segmented design of this application guides the pressure transmission directionally through the transition section 22, making the deformation concentrated in a specific area, significantly improving the dimensional adaptability of small-hole clamping. In the prior art, the radial grooves are mostly locally opened, and the uniform deformation of the overall elastic arms cannot be achieved. However, the through-type main groove 232 structure of this application enables each elastic arm to have consistent deformation response characteristics, effectively eliminating local stress concentration.

[0027] Through the above technical solutions, this application realizes micro-controllable expansion during the clamping process of the small-hole workpiece 9, solving the problem that the excessive expansion of the traditional chuck damages the workpiece 9. The combined use of the stepped segmented structure and the through-type main groove 232 enables the chuck to have the ability of directional deformation while maintaining overall rigidity, significantly improving the clamping stability and positioning accuracy. The plane contact design between the ejector rod 3 and the limiting section 23 disperses the axial pressure, avoiding local wear caused by traditional cusp contact and extending the service life of the clamping assembly.

[0028] In addition, referring to Figure 4 、 Figure 7 - Figure 8 To achieve a firm connection between the inner support chuck 2 and the sub-spindle 1 and ensure the stable transmission of the deformation action during the clamping process, this embodiment further provides an inner support nut 7 and an inner support screw 71. The inner support nut 7 is screwed onto the front end of the sub-spindle 1. One end of the inner support nut 7 is provided with a threaded hole. The inner support chuck 2 can be detachably connected to the inner support nut 7 through the inner support screw 71 and the threaded hole, enabling the inner support chuck 2 to be quickly installed and disassembled, and forming an axial preload with the sub-spindle 1 through the spiral force, improving the rigidity and clamping response speed of the system.

[0029] In one embodiment, the threaded hole and the second through-hole 231 can be set at the same hole position, that is, the threaded hole provided on the limiting section 23 can also serve as the second through-hole 231 while having the installation function, for dispersing the axial force and realizing the integrated design of structure and function.

[0030] In one embodiment, referring toFigure 4 , Figure 7 - Figure 8 The limiting section 23 is also provided with a plurality of auxiliary notches 233 arranged radially. The auxiliary notches 233 refer to groove structures opened radially on the limiting section 23, which can be realized by wire cutting or milling. The depth and width of the notches can be adaptively adjusted according to the material thickness of the limiting section 23. This structure is used to adjust the local stiffness of the limiting section 23 and reduce stress concentration. The radial setting means that the extension direction of the notch is perpendicular to the axis of the inner support chuck 2, and a symmetrical distribution layout can be adopted, for example, evenly spaced in the circumferential area of ​​the limiting section 23. This layout can balance the deformation distribution of the limiting section 23 when it is subjected to axial pressure from the push rod 3.

[0031] Specifically, after the auxiliary notch 233 is provided in the limiting section 23, when the plane end face of the push rod 3 contacts the center of the end face of the limiting section 23 and applies axial pressure, the limiting section 23 produces a slight elastic deformation in the area of ​​the auxiliary notch 233, which complements the deformation in the area of ​​the main notch 232, thereby dispersing the stress concentration. The introduction of the auxiliary notch 233 reduces the local stiffness of the limiting section 23 when transmitting axial pressure, avoiding structural damage caused by excessive stress at the step connection between the transition section 22 and the deformation section 21. At the same time, the auxiliary notch 233 increases the elastic adjustment ability of the limiting section 23 when subjected to force, making the distribution of the clamping force more uniform.

[0032] Further, refer to Figure 4 , Figure 7 - Figure 8 A first through hole 2331 is provided at one end of the auxiliary notch 233 away from the deformation section 21. The first through hole 2331 refers to a circular hole that passes through the end of the auxiliary notch 233, and can be formed by drilling or stamping. Its function is to alleviate the stress concentration phenomenon in the end area of ​​the auxiliary notch 233.

[0033] Specifically, when the push rod 3 applies axial pressure to the limiting section 23, the inner support chuck 2 generates radial expansion deformation, and the auxiliary slot 233 expands with the deformation. At this time, the first through hole 2331 at the end of the auxiliary slot 233 disperses the local stress generated during the expansion process to avoid cracks or fractures at the end of the slot due to stress concentration. For example, when the depth of the auxiliary slot 233 is 10 mm, the diameter of the first through hole 2331 can be set to 2 mm, and the center position of the circle maintains a margin of 0.5 mm from the edge of the slot end, thereby achieving a stress buffering function while maintaining structural strength.

[0034] In one embodiment, referring to Figure 4 , Figure 7 - Figure 8, the limiting section 23 is also provided with a plurality of second through holes 231 evenly distributed circumferentially, which are used to balance the stress distribution of the limiting section 23. Among them, the second through hole 231 refers to a penetrating hole structure provided in the solid material of the limiting section 23, which changes the stress transmission path by reducing the local material density, and can be specifically realized by using circular, elliptical or polygonal hole shapes. The circumferential uniform distribution means that a plurality of through holes are arranged at equal angular intervals around the central axis of the inner support chuck 2, and can be specifically realized by setting a through hole at a fixed angle interval along the circumferential direction of the limiting section 23. For example, a through hole is set every 30 degrees to 120 degrees.

[0035] Specifically, when the axial pressure of the ejector rod 3 acts on the end face of the limiting section 23, the internal stress of the limiting section 23 is redistributed through the hollow structure formed by the second through holes 231, avoiding excessive stress concentration in a specific area. The characteristic that a plurality of through holes are evenly distributed circumferentially makes the stress field symmetric in the circumferential direction, thereby eliminating the clamping eccentricity problem caused by asymmetric deformation. During the clamping process, controllable elastic deformation occurs in the edge area of the through hole, optimizing the overall stiffness of the limiting section 23 while maintaining sufficient deformation coordination ability.

[0036] In one embodiment, referring to Figure 4 , Figure 7 - Figure 8 , the deformation section 21 at least includes a first deformation part 211 and a second deformation part 212. The first deformation part 211 and the second deformation part 212 are coaxially connected in a stepped manner in sequence, and the outer diameter of the first deformation part 211 is smaller than the outer diameter of the second deformation part 212. Among them, the first deformation part 211 refers to the initial deformation area at the front end of the deformation section 21, which can be specifically realized by using a stepped cylindrical structure with a smaller outer diameter. Its smaller outer diameter is beneficial to preferentially generate radial expansion deformation under axial pressure; the second deformation part 212 refers to the secondary deformation area at the rear end of the first deformation part 211, which can be specifically realized by using a stepped cylindrical structure with a larger outer diameter. Its larger outer diameter can provide higher structural stiffness to limit the amount of deformation; the stepped coaxial connection in sequence means that the first deformation part 211 and the second deformation part 212 are connected by an axially stepped surface with a gradually changing outer diameter, and the stepped structure can be specifically formed by turning or grinding. This design enables the deformation section 21 to have a hierarchical deformation guiding ability.

[0037] Specifically, when the ejector rod 3 applies axial pressure, the first deformation part 211 with a smaller outer diameter takes the lead in generating radial deformation, and at this time, the second deformation part 212 still remains relatively rigid to restrict the deformation transmission range; as the pressure increases, the stress concentration area at the stepped connection of the second deformation part 212 begins to participate in the deformation, thereby realizing hierarchical control of the amount of deformation. The two deformation parts form a deformation transition area at the stepped connection, restricting the elastic deformation direction of the deformation section 21 within a predetermined area and avoiding uncontrollable deformation of the overall structure due to force dispersion.

[0038] This embodiment effectively solves the problem of difficult control of directional elastic deformation caused by the dispersion of force in the deformation area of the traditional internal support chuck. When clamping the small-hole workpiece 9, the hierarchical deformation mechanism of the first deformation part 211 and the second deformation part 212 can accurately match the inner hole size of the workpiece 9, avoiding damage to the hole wall caused by excessive single deformation amount. At the same time, the stepped connection structure enhances the anti-torsion ability of the deformation section 21, ensuring uniform distribution of the contact pressure during the clamping process.

[0039] In this embodiment, the deformation section 21 includes at least the first deformation part 211 and the second deformation part 212 as an example for illustration. However, this embodiment is not limited thereto, and the number and structural form of the deformation section 21 can be adjusted and expanded according to actual application requirements. For example, the deformation section 21 may further include multiple structural units such as a third deformation part and a fourth deformation part. The multiple deformation parts can be sequentially arranged in a stepped coaxial manner and are flexibly connected through a transition region, so as to further refine the distribution path of the opening deformation and achieve a more stable elastic expansion effect. Those skilled in the art can reasonably design the number of stages, diameter ratio, and connection method of the deformation section 21 according to different small-hole sizes, clamping strengths, or deformation stroke requirements without departing from the spirit of the present invention, and all should be regarded as the protection scope of this application.

[0040] Further, referring to Figure 4 、 Figure 7 - Figure 8 , the first deformation part 211 and the second deformation part 212 are connected by an arc structure transition and are integrally formed with the internal support chuck 2. Among them, the arc structure transition refers to a curved surface transition structure connecting the boundaries of the first deformation part 211 and the second deformation part 212, which is used to eliminate stress concentration at the stepped connection and guide deformation transmission. Integral forming means that the internal support chuck 2 forms a continuous structure through overall machining, and specifically can be realized by numerical control turning or powder metallurgy processes, which is used to avoid assembly errors and improve structural strength.

[0041] Specifically, when the ejector rod 3 applies an axial pressure to the limiting section 23, the stepped structure of the deformation section 21 causes the first deformation part 211 to preferentially generate radial expansion, while the second deformation part 212 gradually participates in the deformation in the subsequent stage. The arc transition structure between the first deformation part 211 and the second deformation part 212 can disperse the local stress at the stepped connection and at the same time guide the deformation energy to be transmitted axially, avoiding structural failure caused by stress mutation. The integral forming processing method ensures the connection strength and deformation consistency of the two deformation parts, and maintains a stable elastic recovery ability during multiple clamping cycles.

[0042] Compared with the prior art, the stepped connection of the traditional internal support chuck usually adopts a right-angle transition, which is prone to crack after repeated stress; while the split assembly structure will cause discontinuous deformation transmission. This solution reduces the stress concentration coefficient through arc transition and eliminates the assembly gap by means of integral forming process, enabling the two deformation parts to form cooperative deformation when stressed and improving the fatigue resistance of the overall structure. This embodiment effectively solves the problem of reduced life caused by stress concentration in the stepped deformation area, realizes the progressive elastic expansion of the deformation section 21, and at the same time ensures that the clamping assembly has higher deformation control accuracy and long-term use stability during the machining of small-hole workpieces 9.

[0043] In one embodiment, referring to Figure 3 , a limiting part 12 is arranged in the accommodating cavity 11, and the auxiliary spindle 1 restricts the sliding range of the ejector rod 3 through the limiting part 12; it also includes a stroke rod 5 and a stroke control device 6. The stroke rod 5 is slidably arranged in the accommodating cavity 11 of the auxiliary spindle 1. One end of the stroke rod 5 is connected to the stroke control device 6 and can slide towards the internal support chuck 2 under the drive of the stroke control device 6. The other end of the stroke rod 5 is in contact and cooperation with the ejector rod 3 for transmitting the axial driving force to the ejector rod 3. Among them, the limiting part 12 refers to a mechanical structure arranged inside the accommodating cavity 11 for restricting the moving stroke of the ejector rod 3, and can specifically be implemented by an annular boss, a clamping groove or a stepped structure. Through the interaction between the contact surface of the limiting part 12 and the ejector rod 3, the axial displacement range of the ejector rod 3 can be accurately restricted to prevent the deformation of the internal support chuck 2 from exceeding the design threshold due to the excessive forward movement of the ejector rod 3; the stroke rod 5 refers to a power transmission component arranged in the accommodating cavity 11 of the auxiliary spindle 1, and can specifically be implemented by a cylindrical rod or a stepped shaft structure. The stroke rod 5 generates an axial displacement under the drive of the stroke control device 6 and transmits an axial thrust through contact with the end face of the ejector rod 3 to form a rigid driving force chain; the stroke control device 6 refers to an actuator for driving the axial movement of the stroke rod 5, and can specifically be implemented by a hydraulic cylinder, a servo motor or a mechanical claw 63 mechanism. By adjusting the moving distance of the stroke rod 5, the magnitude of the axial pressure applied by the ejector rod 3 to the internal support chuck 2 can be indirectly controlled.

[0044] Specifically, when it is necessary to clamp the small-hole workpiece 9, the stroke control device 6 drives the stroke rod 5 to move along the axis direction of the auxiliary spindle 1, and the front end of the stroke rod 5 remains in contact with the rear end of the ejector rod 3 and transmits the thrust. After the ejector rod 3 receives the thrust, it slides forward, and the front end plane thereof contacts the center of the end face of the limiting section 23 of the internal support chuck 2 and applies an axial pressure. At this time, the limiting part 12 physically blocks the sliding end position of the ejector rod 3 to ensure that the axial pressure is always within the preset safe range. The deformation section 21 of the internal support chuck 2 undergoes radial elastic expansion under the action of the axial pressure, and the deformation is concentrated through the guidance of the transition section 22, and finally the stable clamping of the small-hole workpiece 9 is realized.

[0045] In this embodiment, the axial movement amount of the ejector rod 3 can be accurately controlled during the clamping process of the small-hole workpiece 9, ensuring that the deformation amount of the internal expansion chuck 2 always remains within the safety threshold. This not only avoids damage to the inner hole of the workpiece 9 caused by excessive expansion but also reduces the stress concentration phenomenon in the deformed area of the chuck, extending the service life of the key components.

[0046] Further, referring to Figure 5 - Figure 6 , the stroke control device 6 includes an adjusting nut 61 screwed to the tail of the sub-spindle 1, a support sleeve 62 sleeved on the tail of the sub-spindle 1, and a plurality of pawls 63 rotatably connected to the support sleeve 62; the pawl 63 further includes a fixed end 631 and a free end 632. A plurality of rotation shaft mounting positions are arranged on the outer circumference of the support sleeve 62 at intervals in the circumferential direction. The fixed end 631 is rotatably arranged in the corresponding rotation shaft mounting position. The end face of the adjusting nut 61 has a pressing surface for contacting and pushing each pawl 63. The pawl 63 deflects around the fixed end 631 under the rotational drive of the adjusting nut 61. The free end 632 of each pawl 63 selectively contacts the tail of the stroke rod 5; when the pawl 63 deflects, the free end 632 pushes the stroke rod 5 to slide axially along the sub-spindle 1.

[0047] It should be noted that the adjusting nut 61 refers to an annular part installed at the tail of the sub-spindle 1 by means of threaded connection, which can be specifically realized by a metal sleeve with internal threads and generates axial displacement through rotational movement. The support sleeve 62 refers to an annular bearing structure installed outside the tail of the sub-spindle 1, which can be specifically realized by an interference-fit steel sleeve and is used to provide an installation basis for the pawl 63. The pawl 63 refers to a pushing component with a lever structure, which can be specifically realized by a metal rocker arm with a rotation shaft hole and generates a swinging action by being pushed by the contact of the end face of the adjusting nut 61 when rotated. The rotation shaft mounting position refers to a positioning structure provided on the outer surface of the support sleeve 62 for installing the rotation shaft of the pawl 63, which can be specifically realized by a lug structure with a shaft hole to ensure the rotational freedom of the pawl 63.

[0048] Specifically, when the adjusting nut 61 is rotated, the pressing surface on its end face contacts and applies pressure to the pawl 63, causing the pawl 63 to generate an angular deflection around the fixed end 631. Since the free end 632 of the pawl 63 contacts the tail of the stroke rod 5, this deflection movement is converted into a linear displacement of the stroke rod 5 in the axial direction. The structural design in which a plurality of pawls 63 are evenly distributed in the circumferential direction makes the thrust distribution uniform and avoids the skew of the stroke rod 5. The spaced arrangement of the rotation shaft mounting positions on the support sleeve 62 provides an independent and stable rotation fulcrum for each pawl 63.

[0049] Compared with the prior art, traditional clamping devices usually adopt a single push rod or hydraulic drive method, which has the defects of complex structure and insufficient adjustment accuracy. This solution uses a mechanical lever transmission structure to convert rotational motion into precise linear displacement, avoiding the possible leakage risk of the hydraulic system and reducing the operation complexity at the same time.

[0050] This embodiment realizes the micro-precise control of the stroke of the ejector rod 3, so that the opening amount of the inner support chuck 2 can be stably adjusted within a small size range. The multi-point synchronous pushing mechanism of the pawl 63 effectively prevents the movement jamming of the stroke rod 5, ensures that the clamping force is evenly transmitted to the inner wall of the workpiece 9, and avoids the damage of the workpiece 9 caused by local stress concentration.

[0051] In addition, to further improve the sliding stability and guiding accuracy between the stroke rod 5 and the receiving cavity 11 of the sub-spindle 1, a sliding sleeve 8 is also provided on the outer periphery of the stroke rod 5 in this embodiment. The sliding sleeve 8 can be made of low-friction and high-strength materials, such as polyoxymethylene (POM), polytetrafluoroethylene (PTFE) or oil-impregnated bronze, and is installed between the outer wall of the sub-spindle 1 and the pawl 63 by interference fit or slight clearance fit. The sliding sleeve 8 can effectively reduce the frictional resistance of the pawl 63 during reciprocating sliding.

[0052] In one embodiment, referring to Figure 9 - Figure 10 , a limiting device 4 is further provided between the sub-spindle 1 and the ejector rod 3. The limiting device 4 is used to limit the axial movement and circumferential rotation of the ejector rod 3 in the sub-spindle 1. By providing the limiting device 4 between the sub-spindle 1 and the ejector rod 3, it can effectively prevent the ejector rod 3 from moving forward excessively or deflecting circumferentially during clamping, avoiding the problem of uneven clamping force distribution caused by out-of-control deformation or contact eccentricity, thereby improving the clamping accuracy, structural stability and service life of the device.

[0053] Furthermore, the limiting device 4 includes a third through hole 41 provided on the side wall of the sub-spindle 1, a positioning pin 42 screwed into the third through hole 41, and a chute 43 provided on the outer surface of the ejector rod 3. The end of the positioning pin 42 extends into the chute 43 to limit the axial stroke or circumferential rotation of the ejector rod 3. Among them, the third through hole 41 refers to a through hole structure opened on the side wall of the sub-spindle 1, which can be formed by drilling or milling specifically, and is used to accommodate the installation of the positioning pin 42. The positioning pin 42 refers to a columnar limiting part connected to the third through hole 41 by thread, which can be realized by a pin with an external thread specifically, and is fixed in position by screwing into the third through hole 41. The chute 43 refers to a groove structure extending axially or circumferentially along the outer surface of the ejector rod 3, which can be formed by wire cutting or grinding specifically, and is used to form a sliding limiting fit with the positioning pin 42.

[0054] Specifically, a third through-hole 41 is machined on the side wall of the sub-spindle 1, and the positioning pin 42 is fixedly connected to this hole by threaded connection, and its end extends into the sliding groove 43 on the surface of the ejector rod 3. When the ejector rod 3 slides within the sub-spindle 1, the cooperation between the sliding groove 43 and the positioning pin 42 limits the maximum axial displacement range of the ejector rod 3, preventing the clamping force from getting out of control due to excessive forward or backward movement of the ejector rod 3. At the same time, the contact between the side wall of the sliding groove 43 and the positioning pin 42 restricts the rotational freedom of the ejector rod 3 around its own axis, avoiding circumferential offset of the ejector rod 3 when transmitting pressure, so as to ensure that the contact position between the end face of the ejector rod 3 and the limiting section 23 of the internal expansion chuck 2 always remains in the central area.

[0055] In some specific embodiments, the sliding groove 43 can be designed as a straight groove extending along the axial direction of the ejector rod 3, and its length is matched with the allowable stroke of the ejector rod 3; the end of the positioning pin 42 can adopt a ball head structure to reduce sliding friction; the thread specification of the third through-hole 41 can be adapted to the external thread of the positioning pin 42, for example, using M5 or M6 standard threads.

[0056] Compared with the prior art, the traditional internal expansion chuck lacks axial and circumferential limiting structures for the ejector rod 3, resulting in easy offset or rotation of the ejector rod 3 during the clamping process, and further causing uneven distribution of the clamping force or over-tolerance of the chuck deformation. This solution realizes precise guidance and freedom constraint of the ejector rod 3 through the mechanical cooperation between the sliding groove 43 and the positioning pin 42, eliminating the risk of clamping failure caused by displacement deviation of the ejector rod 3.

[0057] This embodiment can accurately limit the movement range of the ejector rod 3 within the sub-spindle 1, prevent the out-of-control of the chuck deformation caused by axial overload, and at the same time eliminate the problem of contact surface eccentricity caused by the rotation of the ejector rod 3, ensuring uniform transmission of the clamping force to the limiting section 23 of the internal expansion chuck 2, thereby improving the clamping stability and repeatability accuracy of the small-hole workpiece 9.

[0058] On the other hand, to meet the clamping and machining requirements of small-hole workpieces of different sizes, this embodiment also provides a method for machining an internal expansion chuck, including: By installing an external turning tool on the tool holder of a CNC lathe or a sliding headstock lathe, turning the front end of the internal expansion chuck 2 to accurately machine its outer diameter to match the inner hole diameter of the target workpiece 9, so as to obtain a clamping contact surface that fits perfectly with the inner hole of the workpiece 9; After machining, the workpiece 9 to be machined is sleeved on the front end of the machined internal expansion chuck 2 to achieve precise clamping and positioning.

[0059] In order to further broaden the scope of application, the inner support chuck 2 in this embodiment is designed to divide the front end of the chuck into three structural areas of different diameters (first deformation part 211, second deformation part 212, transition section 22), wherein the diameters of the first deformation part 211 and the second deformation part 212 are slightly larger than the inner hole size of the conventional workpiece 9, and appropriate processing allowance is reserved. The user can select the corresponding section for outer diameter processing according to the specific size of the workpiece 9. This multi-section allowance design enables a single inner support chuck 2 to adapt to workpieces 9 with multiple inner hole sizes, significantly improving the versatility and processing flexibility of the inner support chuck 2, reducing the frequency of chuck replacement, reducing processing costs, and meeting the clamping processing requirements for workpieces 9 of different specifications in mass production.

[0060] Reference Figure 11 For example, the diameter of the first deformation portion 211 is 6.5 mm, the diameter of the second deformation portion 212 is 9.5 mm, the inner diameter of the workpiece 9 matched with the first deformation portion 211 is 6 mm, and the inner diameter of the workpiece 9 matched with the second deformation portion 212 is 9 mm.

[0061] It should be noted that Figure 11 The original size of the inner support chuck in the unprocessed state is shown. In actual application, in order to achieve a close fit with the inner hole of the corresponding workpiece, the first deformation part 211 and the second deformation part 212 are usually precisely processed according to the inner diameter size of the target workpiece, so that they form an interference or quasi-interference fit with the inner hole in the open state, thereby ensuring stable clamping force, uniform deformation, and effectively avoiding looseness or damage during the clamping process. Those skilled in the art can flexibly determine the machining allowance and the final fit tolerance according to specific application requirements.

[0062] The above is only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. An internal support clamping assembly for clamping a small hole workpiece, characterized in that: include: A secondary spindle (1), having an accommodating cavity (11) disposed therein; An inner support chuck (2) is connected to the front end of the secondary spindle (1) and comprises a deformation section (21), a transition section (22) and a limiting section (23) in sequence along the axial direction; the deformation section (21), the transition section (22) and the limiting section (23) are coaxially connected in sequence in a stepped manner; the inner support chuck (2) is integrally formed; the inner support chuck (2) is provided with at least three main grooves (232) arranged in a radial direction; the main grooves (232) extend radially from the center position of the limiting section (23) and penetrate the transition section (22) and the deformation section (21) in sequence; the transition section (22) is used to guide the deformation to be concentrated on the deformation section (21); A push rod (3) is slidably disposed in the accommodating cavity (11) of the secondary spindle (1); the front end of the push rod (3) is a plane and can selectively contact the center of the end surface of the limiting section (23) to transmit axial pressure to the inner support chuck (2).

2. The inner support clamping assembly for clamping small hole workpieces according to claim 1 is characterized in that: The limiting section (23) is also provided with a plurality of auxiliary notches (233) arranged along the radial direction.

3. The inner support clamping assembly for clamping a small hole workpiece according to claim 2 is characterized in that: The auxiliary notch (233) is also provided with a first through hole (2331) at one end thereof away from the deformation section (21).

4. The inner support clamping assembly for clamping a small hole workpiece according to claim 1 or 2, characterized in that: The limiting section (23) is also provided with a plurality of second through holes (231) evenly distributed along the circumferential direction, which are used to balance the force distribution of the limiting section (23).

5. The inner support clamping assembly for clamping a small hole workpiece according to claim 1 or 2, characterized in that: The deformation section (21) comprises at least a first deformation portion (211) and a second deformation portion (212); the first deformation portion (211) and the second deformation portion (212) are coaxially connected in sequence in a stepped manner; and the outer diameter of the first deformation portion (211) is smaller than the outer diameter of the second deformation portion (212).

6. The inner support clamping assembly for clamping a small hole workpiece according to claim 5, characterized in that: The first deformable portion (211) and the second deformable portion (212) are connected via an arc structure transition, and are integrally formed with the inner support clamp (2).

7. The inner support clamping assembly for clamping a small hole workpiece according to claim 1 or 2, characterized in that: A limiting portion (12) is provided in the accommodating cavity (11), and the secondary spindle (1) limits the sliding range of the push rod (3) through the limiting portion (12); It also includes a stroke rod (5) and a stroke control device (6), wherein the stroke rod (5) is slidably disposed in the accommodating cavity (11) of the secondary spindle (1), one end of the stroke rod (5) is connected to the stroke control device (6), and can slide toward the inner support chuck (2) under the drive of the stroke control device (6), and the other end of the stroke rod (5) is in contact with the push rod (3) for transmitting the axial driving force to the push rod (3).

8. The inner support clamping assembly for clamping a small hole workpiece according to claim 7, characterized in that: The stroke control device (6) comprises an adjusting nut (61) threadedly connected to the tail of the secondary spindle (1), a support sleeve (62) sleeved on the tail of the secondary spindle (1), and a plurality of pusher claws (63) rotatably connected to the support sleeve (62); The pusher claw (63) further comprises a fixed end (631) and a free end (632); the outer periphery of the support sleeve (62) is provided with a plurality of rotating shaft mounting positions spaced apart along the circumferential direction; the fixed end (631) is rotatably arranged at a corresponding rotating shaft mounting position; the end surface of the adjusting nut (61) has a pushing surface for contacting and pushing each pusher claw (63); the pusher claw (63) deflects around the fixed end (631) under the rotation drive of the adjusting nut (61); and the free end (632) of each pusher claw (63) selectively contacts the tail of the travel rod (5); wherein: When the pusher claw (63) is deflected, the free end (632) pushes the travel rod (5) forward to slide along the axial direction of the secondary main shaft (1).

9. The inner support clamping assembly for clamping a small hole workpiece according to claim 1, characterized in that: A limiting device (4) is also provided between the secondary main shaft (1) and the push rod (3), and the limiting device (4) is used to limit the axial movement and circumferential rotation of the push rod (3) in the secondary main shaft (1).

10. The inner support clamping assembly for clamping a small hole workpiece according to claim 9, characterized in that: The limiting device (4) comprises a third through hole (41) provided on the side wall of the secondary spindle (1), a positioning pin (42) screwed into the third through hole (41), and a slide groove (43) provided on the outer surface of the push rod (3), wherein the end of the positioning pin (42) extends into the slide groove (43) to limit the axial travel or circumferential rotation of the push rod (3).

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