An internal support clamping component for clamping and machining small-hole workpieces

Abstract

An internal support clamping assembly for clamping and machining small-hole workpieces, comprising a sub-spindle with an accommodation cavity provided inside; 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, and 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 accommodation cavity of the sub-spindle, the front end of the push rod is a plane and is used to contact and extrude the center of the end face of the limiting section to transmit axial pressure to the internal support chuck; wherein, the limiting section is further provided with a plurality of auxiliary notches arranged radially. The embodiment of the present invention can form uniform contact during the clamping process, avoid piercing-type damage to the inner wall of the internal support chuck, and effectively extend the service life of the internal support chuck.

Description

Technical Field

[0001] The present invention relates to the technical field of machining fixtures, and particularly relates to an internal support clamping assembly for clamping and machining 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 tightly support 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:

[0004] 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 finished product quality;

[0005] 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;

[0006] 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 the current machining clamping technology. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an internal support clamping assembly for clamping and machining small-hole workpieces in view of the deficiencies of the prior art, so as to overcome the limitations in durability and accuracy of the existing elastic materials and thin-film circuits in the traditional internal support clamping assembly for clamping and machining small-hole workpieces.

[0008] The purpose of the present invention is to provide an internal support clamping assembly for clamping and machining small-hole workpieces in view of the defects and deficiencies of the prior art, including:

[0009] A sub-spindle, which is internally provided with a receiving cavity;

[0010] 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 radially extend 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;

[0011] The ejector rod is slidably disposed in the receiving cavity of the sub-spindle. The front end of the ejector rod is a flat surface and is used to contact and press the center of the end face of the limiting section to transmit axial pressure to the inner chuck.

[0012] Wherein, the limiting section is further provided with a plurality of auxiliary notches arranged radially.

[0013] Furthermore, a first through hole is provided at one end of the auxiliary notch away from the deformation section.

[0014] Furthermore, the limiting section is further provided with a plurality of second through holes evenly distributed in the circumferential direction for balancing the force distribution of the limiting section.

[0015] 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.

[0016] 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 chuck.

[0017] Furthermore, a limiting part is provided in the receiving cavity, and the sub-spindle restricts the sliding range of the ejector rod through the limiting part.

[0018] Furthermore, one end of the stroke rod is connected to the stroke control device and can slide towards the inner chuck under the drive of the stroke control device. 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.

[0019] 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.

[0020] The pawl includes a fixed end and a free end. A plurality of rotation shaft mounting positions are arranged at intervals in the circumferential direction on the outer periphery of the support sleeve. The fixed end is rotatably disposed in the corresponding rotation shaft mounting 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 rotational drive of the adjusting nut, and the free end of each pawl selectively contacts the tail of the stroke rod; wherein,

[0021] When the pawl deflects, the free end pushes the stroke rod to slide axially along the sub-spindle.

[0022] Furthermore, a limiting device is further provided between the sub-spindle and the ejector rod, and the limiting device is used to limit the axial movement and circumferential rotation of the ejector rod in the sub-spindle.

[0023] Further, the limiting device includes a third through hole provided on the side wall of the sub-spindle, a positioning pin screwed into 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.

[0024] In the embodiment of the present invention, by providing a plurality of main grooves in the inner support chuck that extend radially from the center of the limiting section and penetrate to the deformation section, the chuck can achieve that the opening action occurs concentratedly 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 provided with a flat structure, which can form uniform contact during the clamping process compared with the traditional pointed loading form, 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

[0025] 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 the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 is a kind of existing inner support chuck;

[0027] Figure 2 is a cross-sectional view of the existing inner support chuck;

[0028] Figure 3 is a cross-sectional view of the embodiment of the present invention;

[0029] Figure 4 is Figure 3 the enlarged view of part A of

[0030] Figure 5 is the structural schematic diagram of the embodiment of the present invention;

[0031] Figure 6 is Figure 5 the enlarged view of part B of

[0032] Figure 7 is the front view of the embodiment of the present invention;

[0033] Figure 8 is the structural schematic diagram of the inner support chuck of the embodiment of the present invention;

[0034] Figure 9 is the structural schematic diagram of another perspective of the embodiment of the present invention;

[0035] Figure 10 isFigure 9 Enlarged view of part C;

[0036] Figure 11 It is a schematic diagram of the dimensions of the inner support chuck and the workpiece in the embodiment of the present invention.

[0037] Reference numerals:

[0038] 1. Sub-spindle; 11. Accommodating cavity; 12. Limiting portion;

[0039] 2. Inner support chuck; 21. Deformation section; 211. First deformation portion; 212. Second deformation portion; 22. Transition section; 23. Limiting section; 231. Second through hole; 232. Main groove; 233. Auxiliary notch; 2331. First through hole;

[0040] 3. Thumb rod;

[0041] 4. Limiting device; 41. Third through hole; 42. Positioning pin; 43. Slide groove;

[0042] 5. Stroke rod;

[0043] 6. Stroke control device; 61. Adjusting nut; 62. Support sleeve; 63. Pawl; 631. Fixed end; 632. Free end;

[0044] 7. Inner support nut; 71. Inner support screw;

[0045] 8. Slide sleeve;

[0046] 9. Workpiece. Detailed implementation manners

[0047] The present invention will be further described in detail below with reference to the accompanying drawings.

[0048] 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 it is within the scope of the claims of the present invention, it is protected by the Patent Law.

[0049] 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 in conjunction with 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 drawings here can be arranged and designed in various different configurations.

[0050] Accordingly, 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 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.

[0051] Referring to Figure 1 - Figure 2 , in the prior art, the demand for clamping small-hole workpieces 9 in the field of precision machining is increasing. Traditional internal expansion chucks have problems such as insufficient control accuracy of the expansion amount and uneven distribution of contact pressure. When applied to workpieces 9 with a small inner diameter, it is difficult for a rigid structure to achieve micro-deformation adjustment, which is likely 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, traditional chucks often cause surface indentations or elliptical deformations of the workpiece 9 due to the inability to evenly disperse the contact force.

[0052] 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 of the deformation structure, resulting in the inability to concentrate elastic deformation directionally. By analyzing the deformation transmission 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 directional compression of the deformation segment 21; second, a through main groove 232 is provided to enable the chuck to have a controllable radial expansion ability; finally, an 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.

[0053] Therefore, referring to Figure 2 - Figure 10 , an embodiment of the present invention provides an internal expansion clamping assembly for clamping and machining small-hole workpieces, including a sub-spindle 1, an internal expansion chuck 2, and an ejector rod 3. Among them, an accommodation cavity 11 is provided inside the sub-spindle 1; the internal expansion 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, and the internal expansion chuck 2 is integrally formed. The internal expansion 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, sequentially passing 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 accommodation cavity 11, and the front end plane thereof is used to contact and squeeze the center of the end face of the limiting segment 23 to transmit axial pressure to the internal expansion chuck 2. The limiting segment 23 is also provided with a plurality of auxiliary notches 233 arranged radially.

[0054] It should be noted that the sub-spindle 1 refers to the power transmission component that bears the clamping assembly, which can be specifically implemented by a hollow cylinder structure. Its internal accommodation cavity 11 is used to install the ejector rod 3 movement assembly. The deformation section 21 of the internal expansion chuck 2 refers to the area that generates radial elastic deformation; the transition section 22 refers to the intermediate area connecting the deformation section 21 and the limiting section 23, which is used to convert the axial pressure transmitted by the ejector rod 3 into the radial expansion force of the deformation section 21; the limiting section 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 expansion chuck 2, which can be specifically set as straight grooves or spiral grooves distributed at equal angles, and the elastic deformation amount of the chuck is adjusted by controlling the groove width and depth.

[0055] Specifically, when the internal expansion chuck 2 is working, the ejector rod 3 is driven to move axially along the sub-spindle 1. When the front plane of the ejector rod 3 contacts the center of the end face of the limiting section 23, the generated axial pressure is transmitted to the deformation section 21 through the stepped structure. The transition section 22 converts part of the axial pressure into a radial expansion force, guiding the deformation section 21 to generate uniform radial expansion. The existence of the main groove 232 makes the internal expansion chuck 2 form multiple independent elastic arms, and each arm expands outward synchronously under the action of pressure to achieve 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 accurately controlled within a very small range, avoiding the over-positioning problem caused by the overall expansion of the traditional chuck.

[0056] Compared with the prior art, the traditional internal expansion chuck adopts a single-segment 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 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 cannot achieve uniform deformation of the overall elastic arms, while 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.

[0057] Through the above technical solutions, this application realizes the microscopically controllable expansion during the clamping process of the small-hole workpiece 9, and solves the problem that the traditional chuck expands too much and 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 the 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 the traditional cusp contact and extending the service life of the clamping assembly.

[0058] In addition, referring to Figure 4 、 Figure 7 - Figure 8In order to achieve a stable connection between the inner support chuck 2 and the secondary spindle 1 and ensure the stable transmission of the deformation action during the clamping process, the present embodiment further provides an inner support nut 7 and an inner support screw 71. The inner support nut 7 is screwed to the front end of the secondary spindle 1, and a threaded hole is provided at one end of the inner support nut 7. 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, so that the inner support chuck 2 can be quickly assembled and disassembled, and axial pre-tightening is formed with the secondary spindle 1 through the spiral force, thereby improving the rigidity and clamping response speed of the system.

[0059] 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 set on the limiting section 23 can not only have an installation function, but also serve as the second through hole 231 for dispersing axial force to achieve an integrated design of structure and function.

[0060] In one embodiment, referring to Figure 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.

[0061] 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.

[0062] 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.

[0063] Specifically, when the ejector rod 3 applies an axial pressure to the limiting section 23, the inner support chuck 2 undergoes a radial expansion deformation, and the auxiliary notch 233 expands along with the deformation. At this time, the first through hole 2331 at the end of the auxiliary notch 233 disperses the local stress generated during the expansion process, avoiding cracks or fractures at the end of the notch due to stress concentration. For example, when the depth of the auxiliary notch 233 is 10 millimeters, the diameter of the first through hole 2331 can be set to 2 millimeters, and the center position of the hole is kept with a margin of 0.5 millimeters from the edge of the notch end, so as to achieve the stress buffering function while maintaining the structural strength.

[0064] In one embodiment, referring to Figure 4 , Figure 7 - Figure 8 , the limiting section 23 is further provided with a plurality of second through holes 231 evenly distributed in the circumferential direction for balancing 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 every fixed angle along the circumferential direction of the limiting section 23, for example, setting a through hole every 30 degrees to 120 degrees.

[0065] 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 in the circumferential direction makes the stress field symmetric in the circumferential direction, thus 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.

[0066] 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 implemented by 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 implemented by 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 axial stepped surface with a gradually changing outer diameter. Specifically, a stepped structure can be formed by turning or grinding. This design enables the deformation section 21 to have a hierarchical deformation guiding ability.

[0067] Specifically, when the ejector rod 3 applies axial pressure, the first deformation part 211 first undergoes radial deformation due to its smaller outer diameter. At this time, the second deformation part 212 still remains relatively rigid to restrict the deformation transmission range; as the pressure increases, the second deformation part 212 starts to participate in the deformation in the stress concentration area at the stepped connection, thereby realizing the 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 preventing the overall structure from being uncontrollable due to the dispersion of the force.

[0068] This embodiment effectively solves the problem of difficult control of directional elastic deformation caused by the dispersion of the 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.

[0069] In this embodiment, the case where the deformation section 21 at least includes a first deformation part 211 and a second deformation part 212 is taken as an example for illustration. However, this embodiment is not limited thereto. 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 can also 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 flexibly connected through a transition area, thereby further refining the distribution path of the opening deformation and achieving 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.

[0070] Further, with reference to Figure 4 and Figure 7 - Figure 8 , the first deformation part 211 and the second deformation part 212 are connected by an arc structure in a transitional manner and are integrally formed with the inner 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 joint and guide the deformation transmission. Integral forming means that the inner support chuck 2 is formed into a continuous structure through overall machining, and specifically, it can be realized by CNC turning or powder metallurgy processes, which is used to avoid assembly errors and improve the structural strength.

[0071] 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 expand radially, while the second deformation part 212 gradually participates in the deformation in subsequent stages. The arc transition structure between the first deformation part 211 and the second deformation part 212 can disperse the local stress at the stepped joint, 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.

[0072] Compared with the prior art, the stepped joints of traditional inner support chucks usually adopt a right-angle transition, which is prone to cracks 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 with the integral forming process, enabling the two deformation parts to form a coordinated deformation when stressed, and improving the fatigue resistance of the overall structure. This embodiment effectively solves the problem of reduced lifespan 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.

[0073] In one embodiment, with reference to Figure 3, a limiting portion 12 is provided in the accommodating cavity 11, and the auxiliary spindle 1 restricts the sliding range of the ejector rod 3 through the limiting portion 12; it further includes a stroke rod 5 and a stroke control device 6. The stroke rod 5 is slidably disposed 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 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 portion 12 refers to a mechanical structure provided inside the accommodating cavity 11 for restricting the moving stroke of the ejector rod 3, and specifically can be implemented by an annular boss, a clamping groove or a stepped structure. Through the interaction between the contact surface of the limiting portion 12 and the ejector rod 3, the axial displacement range of the ejector rod 3 can be accurately restricted, preventing the ejector rod 3 from moving forward excessively and causing the deformation of the internal chuck 2 to exceed the design threshold; the stroke rod 5 refers to a power transmission member disposed in the accommodating cavity 11 of the auxiliary spindle 1, and specifically can 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 the 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 specifically can be implemented by a hydraulic cylinder, a servo motor or a mechanical pawl 63 mechanism. By adjusting the moving distance of the stroke rod 5, the magnitude of the axial pressure exerted by the ejector rod 3 on the internal chuck 2 can be indirectly controlled.

[0074] 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. 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 receiving the thrust, the ejector rod 3 slides forward, and the front end plane thereof contacts the center of the end face of the limiting section 23 of the internal chuck 2 and applies an axial pressure. At this time, the limiting portion 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 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, finally realizing the stable clamping of the small-hole workpiece 9.

[0075] 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 chuck 2 is always within the safe threshold. It not only avoids the damage to the inner hole of the workpiece 9 caused by excessive expansion, but also reduces the stress concentration phenomenon in the deformation area of the chuck, and prolongs the service life of the key components.

[0076] 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 includes a fixed end 631 and a free end 632, and a plurality of rotation shaft mounting positions are arranged on the outer periphery 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, and the pawl 63 deflects around the fixed end 631 under the rotational drive of the adjusting nut 61, and 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 forward to slide axially along the sub-spindle 1.

[0077] 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, and specifically can be realized by a metal sleeve with internal threads, and axial displacement is generated through rotational movement. The support sleeve 62 refers to an annular bearing structure installed outside the tail of the sub-spindle 1, and specifically can be realized by an interference-fitted steel sleeve, which is used to provide a mounting basis for the pawl 63. The pawl 63 refers to a pushing component with a lever structure, and specifically can be realized by a metal rocker arm with a rotation shaft hole, and its swing action is generated by the contact and push of the end face of the adjusting nut 61 through rotation. The rotation shaft mounting position refers to a positioning structure provided on the outer surface of the support sleeve 62 for mounting the rotation shaft of the pawl 63, and specifically can be realized by a lug structure with a shaft hole to ensure the rotational freedom of the pawl 63.

[0078] Specifically, when the adjusting nut 61 is rotated, the pressing surface on its end face contacts the pawl 63 and applies pressure, 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 motion is converted into a linear displacement of the stroke rod 5 along the axis. The structural design of the plurality of pawls 63 evenly distributed in the circumferential direction makes the thrust distribution uniform, avoiding 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.

[0079] 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 converts the rotational motion into an accurate linear displacement through a mechanical lever transmission structure, avoiding the possible leakage risk of the hydraulic system and reducing the operation complexity at the same time.

[0080] 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.

[0081] In addition, to further improve the sliding stability and guiding accuracy between the stroke rod 5 and the receiving cavity 11 of the sub-main shaft 1, a sliding sleeve 8 is further 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-main shaft 1 and the claw 63 through interference fit or slight clearance fit. The sliding sleeve 8 can effectively reduce the frictional resistance of the claw 63 during reciprocating sliding.

[0082] In one embodiment, referring to Figure 9 - Figure 10 , a limiting device 4 is further provided between the sub-main shaft 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 within the sub-main shaft 1. By providing the limiting device 4 between the sub-main shaft 1 and the ejector rod 3, it is possible to effectively prevent the ejector rod 3 from moving forward excessively or deflecting circumferentially during the clamping process, avoiding problems such as 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.

[0083] Furthermore, the limiting device 4 includes a third through hole 41 provided on the side wall of the sub-main shaft 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-main shaft 1, which can be specifically formed by drilling or milling for accommodating the installation of the positioning pin 42. The positioning pin 42 refers to a columnar limiting member connected to the third through hole 41 by a thread, which can be specifically realized by a pin with an external thread 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 specifically formed by wire cutting or grinding for forming a sliding limiting fit with the positioning pin 42.

[0084] Specifically, the side wall of the sub-main shaft 1 is machined with a third through hole 41, and the positioning pin 42 is fixed in this hole by threaded connection, and its end extends into the chute 43 on the surface of the ejector rod 3. When the ejector rod 3 slides within the sub-main shaft 1, the cooperation between the chute 43 and the positioning pin 42 limits the maximum axial displacement range of the ejector rod 3, preventing the ejector rod 3 from moving forward or backward excessively and causing the clamping force to get out of control. At the same time, the contact between the side wall of the chute 43 and the positioning pin 42 restricts the rotational freedom of the ejector rod 3 around its own axis, avoiding the 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 inner support chuck 2 always remains in the central area.

[0085] 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.

[0086] Compared with the prior art, the traditional internal support chuck lacks the axial and circumferential limiting structures for the ejector rod 3, resulting in the easy deviation or rotation of the ejector rod 3 during the clamping process, and further causing uneven distribution of the clamping force or excessive deformation of the chuck. Through the mechanical cooperation between the sliding groove 43 and the positioning pin 42, this solution realizes the precise guiding and freedom constraint of the ejector rod 3, and eliminates the risk of clamping failure caused by the displacement deviation of the ejector rod 3.

[0087] This embodiment can accurately limit the movement range of the ejector rod 3 within the sub-spindle 1, prevent the out-of-control deformation of the chuck 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 that the clamping force is evenly transmitted to the limiting section 23 of the internal support chuck 2, thereby improving the clamping stability and repeatability of the small-hole workpiece 9.

[0088] 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 support chuck, including:

[0089] By installing an external turning tool on the tool holder of a CNC lathe or a sliding headstock lathe, the front end of the internal support chuck 2 is turned, and its outer diameter is precisely machined to match the inner hole diameter of the target workpiece 9, thereby obtaining a clamping contact surface that perfectly fits the inner hole of the workpiece 9;

[0090] After the machining is completed, the workpiece 9 to be machined is sleeved on the front end of the machined internal support chuck 2 to achieve precise clamping and positioning.

[0091] To further broaden the scope of application, in the design of the internal support chuck 2 in this embodiment, the front end of the chuck is divided into three structural regions with different diameters (the first deformation part 211, the second deformation part 212, and the transition section 22), where 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, leaving appropriate machining allowances. Users can select the corresponding section for outer diameter machining according to the specific size of the workpiece 9. This multi-section allowance design enables a single internal support chuck 2 to adapt to workpieces 9 with multiple inner hole sizes, significantly improving the versatility and machining flexibility of the internal support chuck 2, reducing the frequency of changing the chuck, lowering the machining cost, and meeting the clamping and machining requirements of workpieces 9 with different specifications in mass production.

[0092] Refer to Figure 11, exemplarily, the diameter of the first deformation part 211 is 6.5 mm, the diameter of the second deformation part 212 is 9.5 mm, the inner diameter of the workpiece 9 that cooperates with the first deformation part 211 is 6 mm, and the inner diameter of the workpiece 9 that cooperates with the second deformation part 212 is 9 mm.

[0093] It should be noted that Figure 11 The shown are the original dimensions of the internal support chuck in the unprocessed state. In practical applications, to achieve a tight fit with the inner hole of the corresponding workpiece, usually the first deformation part 211 and the second deformation part 212 need to be precisely machined according to the inner diameter size of the target workpiece, so that an interference or quasi-interference fit is formed with the inner hole in the open state, thereby ensuring stable clamping force, uniform deformation, and effectively avoiding loosening or damage phenomena 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.

[0094] The above is only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, shall all be covered by the scope of the claims 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 is used to contact and squeeze the center of the end surface of the limiting section (23) to transmit axial pressure to the inner support chuck (2); Wherein, the limiting section (23) is further provided with a plurality of auxiliary notches (233) arranged along the radial direction.

2. The inner support clamping assembly for clamping small hole workpieces according to claim 1 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).

3. The inner support clamping assembly for clamping a small hole workpiece according to claim 1 is 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).

4. The inner support clamping assembly for clamping a small hole workpiece according to claim 1 is 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).

5. The inner support clamping assembly for clamping a small hole workpiece according to claim 4 is characterized in that: The first deformable portion (211) and the second deformable portion (212) are connected via an arc structure transition.

6. The inner support clamping assembly for clamping a small hole workpiece according to claim 1, 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 travel rod (5) and a travel control device (6), wherein the travel rod (5) is slidably arranged in the accommodating cavity (11) of the secondary spindle (1), one end of the travel rod (5) is connected to the travel control device (6), and can slide in the direction of the inner support chuck (2) under the drive of the travel control device (6), and the other end of the travel rod (5) is in contact with the push rod (3) to transmit the axial driving force to the push rod (3).

7. The inner support clamping assembly for clamping a small hole workpiece according to claim 6, 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) comprises a fixed end (631) and a free end (632); the outer circumference 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).

8. 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).

9. The inner support clamping assembly for clamping a small hole workpiece according to claim 8, 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), the end of the positioning pin (42) extending into the slide groove (43).

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