CNC machining inner support clamp

Abstract

A CNC machining inner support clamp comprises a base, an air cylinder, a cushion block, an elastic inner support chuck and an extrusion head, and the base is provided with a through hole and a mounting area which is located below the through hole and communicated with the through hole; the cylinder is located in the mounting area and fixedly connected with the base; the cushion block is fixed on the upper surface of the base and provided with a guide hole communicated with the through hole; the upper part of the inner wall of the guide hole is a conical surface; the elastic inner supporting chuck penetrates through the guide hole and the through hole, a clamping part is arranged on the upper portion of the elastic inner supporting chuck, an annular step is arranged on the outer ring face of the clamping part, a plurality of notches are formed in the top face of the clamping part, and the clamping part is divided by the notches to form a plurality of elastic clamping pieces arranged at intervals. The lower part of the elastic inner support chuck is fixedly connected with the inner wall of the through hole and is provided with a penetrating hole communicated with the through hole and the inner area of the clamping part; the extrusion head penetrates through the penetrating hole and the inner area of the clamping part and is fixedly connected with the telescopic end of the air cylinder. The upper portion of the extrusion head is of a conical structure. When the air cylinder drives the extrusion head to move, the conical structure pushes the elastic clamping piece to deflect or leave the elastic clamping piece so as to clamp or release the annular workpiece.

Description

Technical Field

[0001] The utility model relates to the technical field of clamps, in particular to a CNC machining inner support clamp. Background Art

[0002] Workpieces must be positioned before CNC (Computer Number Control) machining to prevent machining defects caused by displacement during processing. The industry typically uses universal fixtures such as chucks, vises, T-screws, and pressure plates to position and clamp workpieces on CNC machines. However, these fixtures are less adaptable for positioning and clamping circular workpieces, making them prone to product shaking due to loose positioning and damage due to excessive pressure.

[0003] At present, the industry mainly adopts a method combining positioning cavity and vacuum adsorption to realize the positioning of circular workpieces. Specifically, a positioning cavity is opened on the fixed column of the fixture, and the bottom of the positioning cavity is connected to the external vacuum device. The side wall of the positioning cavity is used to limit the ring side of the circular workpiece. The bottom of the circular workpiece is firmly attached to the bottom surface of the positioning cavity through vacuum adsorption, thereby realizing the positioning and clamping of the circular workpiece. When the above-mentioned fixture is used to clamp the circular workpiece, a gap must be reserved between the side wall of the positioning cavity and the product to ensure the smooth placement of the product. The existence of the gap will cause the product to shift during the processing, resulting in insufficient product positioning accuracy. Secondly, since the product is limited by vacuum adsorption, its adsorption force is insufficient, and the workpiece will shift or warp during the processing, or even have flying chips. The product positioning is not firm, which will interfere with the normal progress of CNC processing and increase the defective rate of product processing. In addition, the above-mentioned fixtures are dedicated to special machines, and each fixture can only position a corresponding product. When multiple different products need to be clamped for CNC processing, multiple fixtures need to be selected, which increases the product clamping cost. Utility Model Content

[0004] Based on this, it is necessary to provide a CNC machining internal support fixture that has firm and reliable product positioning, high product positioning accuracy, increased product yield and strong versatility to address the above shortcomings.

[0005] A CNC machining internal support fixture for clamping annular workpieces, comprising:

[0006] A base, the base being used to be fixed on a CNC machine, the upper surface of the base being provided with a through hole, and the base being provided with a mounting area communicating with the through hole below the through hole;

[0007] a cylinder, the cylinder being located in the mounting area and fixedly connected to the base;

[0008] A pad, the pad being fixed to the upper surface of the base, and having a guide hole formed on the pad that passes through the upper and lower surfaces of the pad and is in communication with the through hole, wherein at least the upper portion of the inner wall of the guide hole is a conical surface, and the diameter of the guide hole gradually increases from the lower portion of the conical surface to the upper portion of the conical surface;

[0009] An elastic inner support chuck, wherein the elastic inner support chuck is penetrated by the guide hole and the through hole, the upper part of the elastic inner support chuck has a clamping part with a conical ring structure and extending out of the upper surface of the pad, the outer ring surface of the clamping part is provided with an annular step located above the pad and used to receive the circular workpiece in an area adjacent to the top of the clamping part, the shape of the outer ring surface of the clamping part in the area below the annular step is adapted to the shape of the conical surface, the top surface of the clamping part is provided with a plurality of notches extending toward the lower part of the elastic inner support chuck and penetrating the upper and lower surfaces of the annular step, the plurality of notches jointly dividing the clamping part to form a plurality of elastic clips arranged at intervals along an annular path; the lower part of the elastic inner support chuck is fixedly connected to the inner wall of the through hole, and the lower part of the elastic inner support chuck is provided with a through hole penetrating the lower surface of the elastic inner support chuck and communicating with the through hole and the inner area of ​​the clamping part; and

[0010] An extrusion head passes through the through-hole and the inner area of ​​the clamping portion and is fixedly connected to the telescopic end of the cylinder. The upper part of the extrusion head is a conical structure, and the shape of the ring side surface of the extrusion head is adapted to the shape of the inner ring surface of the clamping portion. When the extrusion head moves in the through-hole driven by the cylinder, the conical structure pushes each elastic clip to deflect in the direction away from the center of the circular workpiece to clamp the circular workpiece, or the conical structure leaves the elastic clip to reset the elastic clip and release the circular workpiece.

[0011] In one embodiment, a mounting groove communicating with the through hole is provided in the base, the space in the mounting groove forms the mounting area, and the cylinder is accommodated in the mounting groove and fixedly connected to the inner wall of the mounting groove.

[0012] In one embodiment, the base includes a fixed base plate, a cylinder fixing plate located above the fixed base plate, and a plurality of support rods arranged between the fixed base plate and the cylinder fixing plate and distributed at intervals, one end of the support rod is fixedly connected to the fixed base plate, and the other end of the support rod is fixedly connected to the cylinder fixing plate. The fixed base plate, the cylinder fixing plate and the plurality of support rods together form the installation area, and the through hole penetrating the upper and lower surfaces of the cylinder fixing plate is opened at a position corresponding to the installation area on the cylinder fixing plate, and the cylinder is located in the installation area and fixedly connected to the lower surface of the cylinder fixing plate.

[0013] In one embodiment, the width of the fixed base plate is greater than the width of the cylinder fixed plate, and the fixed base plate is provided with mounting notches penetrating the upper, lower and side surfaces of the fixed base plate.

[0014] In one embodiment, the CNC machined inner support fixture further includes a throttle valve mounted on the cylinder and used to control the air intake of the cylinder.

[0015] In one embodiment, the CNC machining internal support fixture also includes a connecting column, which is fixedly connected to the telescopic end of the cylinder, and the upper surface of the connecting column is provided with a non-circular positioning step, and the non-circular positioning step is provided with a positioning hole, and the lower surface of the extrusion head is provided with a non-circular slot that matches the non-circular positioning step and is connected to the positioning hole, and the upper surface of the extrusion head is provided with a countersunk hole that is connected to the non-circular slot, and the extrusion head is fixedly connected to the connecting column by a screw that penetrates the countersunk hole and the non-circular slot and is inserted into the positioning hole.

[0016] In one embodiment, a threaded column is provided at the bottom of the connecting column, and the threaded column is threadedly connected to the telescopic end of the cylinder.

[0017] In one embodiment, the height of the tapered surface is the same as the thickness of the spacer.

[0018] In one embodiment, the height of the conical surface is smaller than the thickness of the spacer, and a guide portion with a constant aperture is provided below the conical surface in the guide hole.

[0019] In one embodiment, the conical surface is a circular conical surface or a polygonal conical surface with an edge number of N, where N is an integer greater than or equal to 3; the conical structure is a circular cone or a polygonal conical surface with an edge number of N, where N is an integer greater than or equal to 3.

[0020] The CNC machining internal support clamp of the present invention is implemented by driving the extrusion head up and down through a cylinder to squeeze or relax the elastic internal support clamp, so that the elastic clip on the elastic internal support clamp is offset or reset to clamp or release the circular workpiece. Compared with the vacuum adsorption method, the cylinder drive method has a greater force on the workpiece, and the product positioning is more firm and reliable, which can prevent the occurrence of offset, warping or flying pieces during processing, ensures the normal progress of CNC processing, and is conducive to improving the yield rate of product processing; the product is clamped by the deformation and deflection of the elastic clip, which can ensure that no gap is left when the internal support tightens the product, prevents the product from being offset during processing, improves the positioning accuracy of the product, and tightens the product by elastically stretching the elastic clip. A clamp can be used to clamp multiple products of similar sizes. The clamp has strong versatility and reduces the clamping cost of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a CNC-machined inner support fixture in one embodiment of the present invention;

[0022] Figure 2 This is a schematic cross-sectional view of a CNC-machined inner support fixture in one embodiment of the present invention;

[0023] Figure 3 This is a schematic cross-sectional view of another state of a CNC-machined inner support fixture in one embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the exploded structure of a CNC-machined inner support fixture in one embodiment of the present invention;

[0025] Figure 5 This is a structural diagram of a base in one embodiment of the present utility model;

[0026] Figure 6 This is a structural diagram of a cushion block in one embodiment of the present utility model;

[0027] Figure 7 This is a schematic cross-sectional structural diagram of a cushion block in one embodiment of the present invention;

[0028] Figure 8 This is a schematic structural diagram of an elastic inner support chuck in one embodiment of the present utility model;

[0029] Figure 9 This is a schematic structural diagram of an extrusion head in one embodiment of the present utility model;

[0030] Figure 10 This is a schematic structural diagram of a connecting column in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Please combine Figure 1-4 as well as Figure 8The utility model discloses a CNC machining internal support fixture which has firm and reliable product positioning, high product positioning accuracy, increased product yield and strong versatility. The CNC machining internal support fixture is used to clamp annular workpieces. The annular workpiece to be clamped can be an overall annular structure or a part of it can be an annular structure (that is, the part to be clamped is an annular structure). Specifically, the CNC machining internal support fixture includes a base 100, a cylinder 200, a pad 300, an elastic internal support chuck 400 and an extrusion head 500. The base 100 is used to be fixed on the CNC machine. A through hole 110 is provided on the upper surface of the base 100. An installation area 120 connected to the through hole 110 is provided on the base 100 below the through hole 110. The cylinder 200 is located in the installation area 120 and is fixedly connected to the base 100. That is, the through hole 110 on the base 100 is used as a connection channel for the telescopic end of the cylinder 200 (that is, the piston rod of the cylinder 200). The cylinder 200 is used to provide power for the extrusion head 500 to move along the height direction of the base 100. The spacer 300 is fixed to the upper surface of the base 100. A guide hole 310 is defined on the spacer 300, extending through both its upper and lower surfaces and correspondingly communicating with the through hole 110. At least the upper portion of the inner wall of the guide hole 310 is a tapered surface 311. Since the tapered surface 311 constitutes the inner wall of the guide hole 310, the tapered surface 311 in this embodiment is not the outer surface of the tapered structure, but rather the inner wall used to enclose the tapered space. The diameter of the guide hole 310 gradually increases from the lower portion of the tapered surface 311 to the upper portion. In other words, the upper portion of the guide hole 310 forms a trumpet-shaped structure with an upward opening.

[0033] The elastic inner support chuck 400 is provided with a guide hole 310 and a through hole 110. The upper portion of the elastic inner support chuck 400 has a clamping portion with a conical ring structure that extends outward from the upper surface of the spacer block 300. In other words, the upper portion of the elastic inner support chuck 400 also has a trumpet-shaped structure with an opening facing upward. The outer annular surface of the clamping portion is provided with an annular step 410 located above the spacer block 300 and used to receive the annular workpiece in an area adjacent to the top of the clamping portion. The shape of the outer annular surface of the clamping portion below the annular step 410 is adapted to the shape of the conical surface. In this embodiment, the outer annular surface of the clamping portion is cylindrical in the area above the annular step 410. When clamping the annular workpiece, the annular step 410 supports the lower surface of the annular workpiece, and the outer annular surface of the clamping portion, which is cylindrical above the annular step 410, abuts against the inner annular surface of the annular workpiece. The top surface of the clamping portion is provided with a plurality of notches 420 extending toward the lower portion of the elastic inner support chuck 400 and penetrating the upper and lower surfaces of the annular step 410. These notches 420 collectively divide the clamping portion to form a plurality of elastic clips 430 spaced along an annular path. In this embodiment, by adapting the shape of the outer annular surface of the clamping portion below the annular step 410 to the shape of a conical surface, the inner wall of the guide hole 310 in the spacer block 300 protects the elastic inner support chuck 400, preventing the elastic clips 430 of the elastic inner support chuck 400 from deflecting when expanded, thereby ensuring the stability and reliability of the elastic clips 430 in clamping the annular workpiece. The lower portion of the elastic inner support chuck 400 is fixedly connected to the inner wall of the through hole 110. A through hole 440 is also provided in the lower portion of the elastic inner support chuck 400, penetrating the lower surface of the elastic inner support chuck 400 and communicating with the through hole 110 and the inner area of ​​the clamping portion. That is, the lower portion of the elastic inner supporting chuck 400 is fixed on the base 100 to achieve positioning of the elastic inner supporting chuck 400 .

[0034] The extrusion head 500 passes through the through-hole 440 and the interior area of ​​the clamping portion and is fixedly connected to the telescopic end of the cylinder 200. The upper portion of the extrusion head 500 has a conical structure, and the shape of the side surface of the extrusion head 500 is adapted to the shape of the inner annular surface of the clamping portion. That is, in this embodiment, the width or diameter of the conical structure on the upper portion of the extrusion head 500 gradually decreases from the top to the bottom of the conical structure. Correspondingly, the width or diameter of the area enclosed by the inner annular surface of the clamping portion (the conical area) gradually decreases from the top to the bottom of the clamping portion. When the extrusion head 500 is driven by the cylinder 200 to move within the through-hole 440, the conical structure pushes each elastic clip 430 to deflect away from the center of the annular workpiece to clamp the annular workpiece, or the conical structure moves away from the elastic clip 430, causing the elastic clip 430 to return to its original position and release the annular workpiece. Specifically, when the cylinder 200 drives the extrusion head 500 toward the base 100, the outer wall of the conical structure on the extrusion head 500 compresses the inner surface of the elastic clip 430, causing the top of the elastic clip 430 to deflect and deform in a direction away from the center axis of the telescopic end of the cylinder 200, thereby clamping the annular workpiece sleeved on the top of the elastic clip 430. When the cylinder 200 drives the extrusion head 500 toward the base 100, the outer wall of the conical structure on the extrusion head 500 leaves the inner surface of the elastic clip 430, and the constraint on the elastic clip 430 is released. The elastic clip 430 recovers its deformation and returns to its original position, thereby releasing the annular workpiece so that it can be removed from the fixture.

[0035] The above-mentioned CNC machining internal support fixture drives the extrusion head 500 to rise and fall by the cylinder 200 to achieve the squeezing or relaxation of the elastic internal support chuck 400, so that the elastic clip 430 on the elastic internal support chuck 400 is offset or reset to clamp or release the circular workpiece. Compared with the vacuum adsorption method, the cylinder 200 drive method has a greater force on the workpiece, and the product positioning is more firm and reliable, which can prevent the occurrence of offset, warping or flying pieces during processing, ensure the normal progress of CNC processing, and help improve the yield rate of product processing; the product is clamped by the deformation and deflection of the elastic clip 430, which can ensure that no gap is left when the internal support is tightened to prevent the product from being offset during processing, improve the positioning accuracy of the product, and tighten the product by elastically stretching the elastic clip 430. A single fixture can meet the clamping needs of multiple products of similar sizes. The fixture has strong versatility and reduces the clamping cost of the product.

[0036] The base 100 is used as a supporting mechanism for the cylinder 200 and the pad 300. Figure 4 and Figure 5In one embodiment, the base 100 includes a fixed base plate 130, a cylinder fixing plate 140 located above the fixed base plate 130, and a plurality of support rods 150 arranged between the fixed base plate 130 and the cylinder fixing plate 140 and distributed at intervals. One end of the support rod 150 is fixedly connected to the fixed base plate 130, and the other end of the support rod 150 is fixedly connected to the cylinder fixing plate 140. The fixed base plate 130, the cylinder fixing plate 140 and the plurality of support rods 150 together form an installation area 120. A through hole 110 is opened on the cylinder fixing plate 140 at a position corresponding to the installation area 120, which passes through the upper and lower surfaces of the cylinder fixing plate 140. The cylinder 200 is located in the installation area 120 and is fixedly connected to the lower surface of the cylinder fixing plate 140. Preferably, four support rods 150 are provided between the fixed base plate 130 and the cylinder fixing plate 140. The four support rods 150 are evenly arranged along a circular path in the area between the fixed base plate 130 and the cylinder fixing plate 140. The support rods 150 are screwed to the fixed base plate 130 and the cylinder fixing plate 140, respectively. Similarly, the cylinder body of the cylinder 200 is screwed to the lower surface of the cylinder fixing plate 140. Furthermore, the width of the fixed base plate 130 is greater than the width of the cylinder fixing plate 140, and the fixed base plate 130 is provided with mounting notches 131 that penetrate the upper and lower surfaces and the side surfaces of the fixed base plate 130. The mounting notches 131 serve as the connection between the fixed base plate 130 and the CNC machine. When the fixture is installed, the fixture is fixed to the CNC machine via bolts passing through the mounting notches 131. In another embodiment, a mounting groove connected to the through hole 110 is opened in the base 100, and the space in the mounting groove forms a mounting area 120. The cylinder 200 is accommodated in the mounting groove and fixedly connected to the inner wall of the mounting groove. In this embodiment, an openable and closable cover is provided at the bottom or side of the base 100 to facilitate placing the cylinder 200 in the mounting groove.

[0037] In one embodiment, the CNC machined internal support fixture further includes a throttle valve 600 installed on the cylinder 200 and used to control the air intake of the cylinder 200. By operating the throttle valve 600, the amount of air entering the cylinder 200 can be adjusted, thereby controlling the driving force on the piston of the cylinder 200, so as to achieve the purpose of controlling the movement of the extrusion head 500 and the extrusion force of the extrusion head 500 on the elastic clip 430.

[0038] It should be noted that in this embodiment, the elastic inner support clamp is made of an elastic material, such as copper, stainless steel, or plastic. This ensures that when the notch 420 is formed in the elastic inner support clamp, the elastic clip 430 formed can deform under the push of the extrusion head 500 and can recover its deformation and return to its original position when the extrusion force is released. The notch 420 provides deformation space for the elastic clip 430 to deflect and return (open and close) under the push of the extrusion head 500. The depth of the notch 420 along the height direction of the clamping portion must meet the requirement that when the extrusion head 500 pushes the elastic clip 430, the deformation amount generated by the elastic clip 430 deviating from the center of the annular workpiece enables the elastic clip 430 to clamp the annular workpiece. In one embodiment, the conical surface within the spacer 300 is a conical surface or a multi-sided pyramidal surface with an edge number N, where N is an integer greater than or equal to 3, for example, the conical surface is a quadrangular pyramidal surface. Preferably, the tapered surface is a conical surface, and accordingly, the area below the annular step 410 on the outer annular surface of the clamping portion is a conical surface, thereby reducing the difficulty of installing the elastic inner support chuck 400 in the spacer 300. Similarly, the tapered structure is a cone or a polygonal pyramid with an edge number N, where N is an integer greater than or equal to 3. In this embodiment, the tapered structure is a cone, and the inner annular surface of the clamping portion is a conical surface. In this way, the extrusion head 500 does not need to be aligned with the elastic inner support chuck 400 in the circumferential direction when passing through the elastic inner support chuck 400, thereby reducing the difficulty of installing the extrusion head 500.

[0039] In one embodiment, the height of the tapered surface 311 is the same as the thickness of the spacer 300, that is, the entire inner surface of the guide hole 310 is the tapered surface 311. In another embodiment, please combine Figure 6 and Figure 7 The height of the conical surface 311 is less than the thickness of the pad 300, and an equal-aperture guide portion 312 is provided below the conical surface 311 in the guide hole 310. The equal-aperture guide portion 312 forms a cylindrical space, and the inner contour shape of the guide hole 310 is adapted to the outer contour shape of the elastic inner support clamp. By providing the equal-aperture guide portion 312, a movement margin is provided for the jacking of the extrusion head 500, so that the extrusion head 500 can protrude from the top of the elastic inner support clamp 400 during the jacking process. In this way, when clamping a cover-shaped workpiece with a circular ring structure, after the processing is completed, the extrusion head 500 can lift the workpiece while lifting, so as to reduce the difficulty of removing the workpiece.

[0040] Please combine Figure 4 as well as Figure 9-10The CNC machined internal support fixture also includes a connecting column 700, which is fixedly connected to the telescopic end of the cylinder 200. The upper surface of the connecting column 700 is provided with a non-circular positioning step 710, and a positioning hole 720 is provided on the non-circular positioning step 710. The lower surface of the extrusion head 500 is provided with a non-circular slot 510 that matches the non-circular positioning step 710 and is connected to the positioning hole 720. The upper surface of the extrusion head 500 is provided with a countersunk hole 520 that is connected to the non-circular slot 510. The extrusion head 500 is fixedly connected to the connecting column 700 by penetrating the countersunk hole 520 and the non-circular slot 510 and inserting a screw into the positioning hole 720. In this embodiment, the provision of the connecting post 700 allows for a fixed connection between the extrusion head 500 and the telescopic end of the cylinder 200. However, due to the long-term friction between the extrusion head 500 and the elastic inner support clamp 400, when the extrusion head 500 becomes difficult to continuously and effectively squeeze the elastic clip 430 due to wear, the extrusion head 500 can be removed and replaced separately, and the connecting post 700, which serves as the connecting component between the extrusion head 500 and the cylinder 200, does not need to be replaced, thereby reducing the cost of the CNC internal support fixture. Furthermore, in this embodiment, the extrusion head 500 and the connecting post 700 are pre-positioned by the non-circular positioning step 710 and the non-circular slot 510, reducing the difficulty of assembling the extrusion head 500 and the connecting post 700. Furthermore, in this embodiment, the bottom of the connecting post 700 is provided with a threaded post 730, which is threadedly connected to the telescopic end of the cylinder 200. This reduces the difficulty of disassembling and assembling the connecting post 700 from the telescopic end of the cylinder 200, thereby improving the assembly efficiency of the CNC internal support fixture.

[0041] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0042] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A CNC machining internal support fixture for clamping annular workpieces, characterized in that: include: A base, the base being used to be fixed on a CNC machine, the upper surface of the base being provided with a through hole, and the base being provided with a mounting area communicating with the through hole below the through hole; a cylinder, the cylinder being located in the mounting area and fixedly connected to the base; A pad, the pad being fixed to the upper surface of the base, and having a guide hole formed on the pad that passes through the upper and lower surfaces of the pad and is in communication with the through hole, wherein at least the upper portion of the inner wall of the guide hole is a conical surface, and the diameter of the guide hole gradually increases from the lower portion of the conical surface to the upper portion of the conical surface; The elastic inner support chuck is provided with the guide hole and the through hole, and the upper part of the elastic inner support chuck has a clamping portion with a conical ring structure and extending out of the upper surface of the pad, and the outer ring surface of the clamping portion is provided with an annular step located above the pad and used to receive the circular workpiece in an area adjacent to the top of the clamping portion, and the shape of the outer ring surface of the clamping portion in the area below the annular step is adapted to the shape of the conical surface, and the top surface of the clamping portion is provided with a plurality of notches extending toward the lower part of the elastic inner support chuck and passing through the upper and lower surfaces of the annular step, and the plurality of notches jointly divide the clamping portion to form a plurality of elastic clips arranged at intervals along an annular path; the lower part of the elastic inner support chuck is fixedly connected to the inner wall of the through hole, and the lower part of the elastic inner support chuck is provided with a through hole that passes through the lower surface of the elastic inner support chuck and is connected with the through hole and the inner area of ​​the clamping portion; as well as An extrusion head passes through the through-hole and the inner area of ​​the clamping portion and is fixedly connected to the telescopic end of the cylinder. The upper part of the extrusion head is a conical structure, and the shape of the ring side surface of the extrusion head is adapted to the shape of the inner ring surface of the clamping portion. When the extrusion head moves in the through-hole driven by the cylinder, the conical structure pushes each elastic clip to deflect in the direction away from the center of the circular workpiece to clamp the circular workpiece, or the conical structure leaves the elastic clip to reset the elastic clip and release the circular workpiece.

2. The CNC machining inner support fixture according to claim 1, characterized in that: A mounting groove communicating with the through hole is provided in the base, and a space in the mounting groove forms the mounting area. The cylinder is accommodated in the mounting groove and fixedly connected to an inner wall of the mounting groove.

3. The CNC machining inner support fixture according to claim 1, characterized in that: The base includes a fixed base plate, a cylinder fixing plate located above the fixed base plate, and a plurality of support rods arranged between the fixed base plate and the cylinder fixing plate and distributed at intervals. One end of the support rod is fixedly connected to the fixed base plate, and the other end of the support rod is fixedly connected to the cylinder fixing plate. The fixed base plate, the cylinder fixing plate and the plurality of support rods together form the installation area. The position of the cylinder fixing plate corresponding to the installation area is provided with the through hole penetrating the upper and lower surfaces of the cylinder fixing plate. The cylinder is located in the installation area and fixedly connected to the lower surface of the cylinder fixing plate.

4. The CNC machining inner support fixture according to claim 3, characterized in that: The width of the fixed base plate is greater than that of the cylinder fixed plate, and the fixed base plate is provided with installation notches which penetrate through the upper, lower and side surfaces of the fixed base plate.

5. The CNC machining inner support fixture according to any one of claims 2 to 4, characterized in that: It also includes a throttle valve installed on the cylinder and used to control the amount of air intake in the cylinder.

6. The CNC machining inner support fixture according to claim 1, characterized in that: It also includes a connecting column, which is fixedly connected to the telescopic end of the cylinder. The upper surface of the connecting column is provided with a non-circular positioning step, and a positioning hole is provided on the non-circular positioning step. The lower surface of the extrusion head is provided with a non-circular slot that matches the non-circular positioning step and is connected to the positioning hole. The upper surface of the extrusion head is provided with a countersunk hole that is connected to the non-circular slot. The extrusion head is fixedly connected to the connecting column by a screw that penetrates the countersunk hole and the non-circular slot and is inserted into the positioning hole.

7. The CNC machining inner support fixture according to claim 6, characterized in that: A threaded column is provided at the bottom of the connecting column, and the threaded column is threadedly connected to the telescopic end of the cylinder.

8. The CNC machining inner support fixture according to claim 1, characterized in that: The height of the conical surface is the same as the thickness of the pad.

9. The CNC machining inner support fixture according to claim 1, characterized in that: The height of the conical surface is smaller than the thickness of the pad, and a guide portion with a constant aperture is provided below the conical surface in the guide hole.

10. The CNC machining inner support fixture according to claim 1, characterized in that: The conical surface is a circular conical surface or a polygonal conical surface with an edge number of N, where N is an integer greater than or equal to 3; the conical structure is a circular cone or a polygonal conical surface with an edge number of N, where N is an integer greater than or equal to 3.

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