An internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipe fittings

Abstract

The present invention discloses an internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipe fittings, comprising a core shaft, a return spring, a connecting ring, a support sleeve, an expansion strip, a conical spring, a guide pull head, and a locking piece; the return spring, support sleeve, and expansion strip constitute a support unit assembly, which is sleeved on the core shaft, connected by a connecting ring, and then inserted into the pipe fitting; the force applied to the locking piece causes the two guide pull heads to move axially toward each other, thereby causing the expansion strip to fit tightly against the connecting ring; the expansion strip expands radially under the push of the connecting ring tapered shaft section, thereby clinging to the inner wall of the pipe fitting, thereby supporting and tightening the pipe fitting; at this time, the return spring is in a compressed state, and the conical spring is in a stretched state; when the locking piece is released, the return spring causes the guide pull head and the connecting ring to move to both sides, and the conical spring resets the expansion strip. The present invention satisfies the processing requirements of pipe fittings of different diameters and has a simple structure and convenient operation.

Description

Technical Field

[0001] The invention belongs to the field of tooling fixtures, and in particular relates to an internal support fixture for cylindrical grinding of slender, thin-walled pipe fittings made of hard and brittle materials. Background Art

[0002] Nuclear fuel cladding tubes, exposed to high temperatures and neutron radiation, are the primary barrier to safe nuclear power operation. These tubes place stringent demands on the material's high-temperature chemical stability, mechanical properties, corrosion resistance, and radiation resistance. Existing zirconium alloy cladding tubes are increasingly unable to meet the demands of advanced nuclear power technology. Ceramic materials or ceramic-based composites (such as SiCf / SiC) offer high-temperature resistance, radiation resistance, safety, reliability, and high accident tolerance, representing the next generation of accident-resistant nuclear fuel cladding materials with the most passive safety features.

[0003] Ceramic or ceramic-based composite cladding tubes range in length from 1 to 4 meters, with an outer diameter of 10 to 20 mm and a wall thickness of approximately 1 mm. High precision machining of the outer surface is required. Due to their large aspect ratio, thin wall thickness, and low overall rigidity, the material is hard and brittle, easily breaking or shattering under stress, making clamping during precision grinding extremely difficult.

[0004] Currently, there are very few documents on fixtures for machining the outer cylindrical surface of slender, thin-walled pipes made of hard and brittle materials. Patent CN112548701A proposes a flexible pneumatic expansion clamp for the inner hole of slender, hard and brittle, thin-walled pipes. The flexible ring on the hollow core shaft expands under the action of compressed air to support and clamp the pipe. However, it cannot adapt to the machining of workpieces with different radii and requires a special air source. The structure is relatively complex, sealing is relatively difficult, and there are certain safety hazards when the pressure is high.

[0005] In view of this, this patent is applied for. Summary of the Invention

[0006] The purpose of the present invention is to provide an internal support clamp for cylindrical grinding of slender, thin-walled, hard and brittle material pipe fittings. The clamp applies a supporting force to the inner wall of the thin-walled pipe through an expansion strip to prevent the thin-walled pipe from being brittle and broken during processing, and can adapt to the processing of pipe fittings of different diameters.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipe fittings, comprising a core shaft with threaded sections processed at both ends;

[0009] A plurality of return springs and connecting rings are sleeved on the core shaft, wherein a connecting ring is provided between two adjacent return springs, and the connecting ring comprises a round shaft segment and tapered shaft segments provided at both ends of the round shaft segment;

[0010] A support sleeve sleeved on the circular shaft section of the connecting ring, wherein the support sleeve is a hollow tubular structure, and a plurality of annular guide grooves and mounting holes are processed on the wall surface;

[0011] An expansion strip is provided in the guide groove, the expansion strip comprising a guide plate and a support plate mounted on the top of the guide plate, the top surface of the support plate being an arc surface matching the inner wall of the pipe fitting, the bottom ends of the guide plate being machined into inclined surfaces, and the inclined surfaces slidingly engaging with the tapered shaft section of the connecting ring after the guide plate passes through the guide groove;

[0012] a conical spring disposed in the mounting hole, wherein the small-diameter end of the conical spring passes through the mounting hole and is connected to the support plate, and the large-diameter end of the conical spring has a diameter larger than the diameter of the mounting hole;

[0013] The return spring, support sleeve and expansion strip constitute a support unit assembly, which is sleeved on the core shaft and connected by a connecting ring and then inserted into the pipe;

[0014] A guide pull head is mounted on both ends of the core shaft, and the guide pull head includes a cylindrical section and a tapered section, and the tapered section is in sliding engagement with the inclined surface of the guide plate located at the end of the core shaft;

[0015] The locking piece arranged on the threaded section of the core shaft acts on the locking piece to make the two guide pull heads move axially toward each other, thereby making the expansion strip fit tightly against the connecting ring. The expansion strip expands radially under the push of the tapered shaft section of the connecting ring, and then fits tightly against the inner wall of the pipe fitting, thereby achieving support and tightening of the pipe fitting; at this time, the reset spring is in a compressed state and the conical spring is in a stretched state, the locking piece is loosened, the reset spring causes the guide pull head and the connecting ring to move to both sides, and the conical spring resets the expansion strip.

[0016] Furthermore, the core shaft is provided in plurality according to the length of the pipe, and the support unit assembly is also provided in plurality according to the inner diameter and length of the pipe.

[0017] Furthermore, the circular side surface of the tapered shaft section of the connecting ring is composed of multiple wedge-shaped surfaces.

[0018] Furthermore, a flexible absorption sleeve made of soft elastic material is provided on the arc surface of the expansion strip.

[0019] Furthermore, four expansion strips are provided on the supporting sleeve.

[0020] The present invention adopts multiple expansion strips for support, improves the rigidity of a single expansion strip in the context of slender pipe processing, and realizes effective support for slender thin-walled pipes; through conical surface sliding fit, it meets the processing needs of pipes with different diameters, has a simple structure and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1It is an axial side schematic diagram of the present invention.

[0022] Figure 2 It is a schematic axial cross-sectional view of the present invention.

[0023] Figure 3 It is a radial cross-sectional schematic diagram of the present invention.

[0024] Figure 4 It is a partial structural diagram of the present invention.

[0025] Figure 5 It is a schematic diagram of the expansion strip structure of the present invention.

[0026] Figure 6 It is a schematic diagram of the connecting ring structure of the present invention.

[0027] Figure 7 It is a schematic diagram of the support sleeve structure of the present invention.

[0028] Markings in the figure: 1. Core shaft; 2. Return spring; 3. Connecting ring; 4. Support sleeve; 5. Expansion strip; 6. Conical spring; 7. Guide pull head; 8. Locking piece; 9. Flexible absorption sleeve; 10. Pipe fitting; 12. Guide plate; 13. Support plate; 15. Guide groove; 16. Mounting hole. DETAILED DESCRIPTION

[0029] like Figures 1 to 7 As shown, this embodiment provides an internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipe fittings, comprising a core shaft 1, a return spring 2, a connecting ring 3, a support sleeve 4, a tightening strip 5, a conical spring 6, a guide pull head 7 and a locking piece 8; threaded sections are machined at both ends of the core shaft 1 for cooperating with the locking piece 8 to achieve thread locking, and the length between the two threaded ends is the length of the pipe fitting 10. In order to meet the different lengths of the pipe fittings 10, the core shaft 1 is provided with multiple ones according to the key length, and the core shaft 1 of the corresponding specification length is selected each time according to the length of the pipe fitting 10.

[0030] like Figure 4 As shown, a plurality of the reset springs 2 are sleeved on the core shaft 1, and the core shafts 1 of two adjacent reset springs 2 are sleeved with the connecting ring 3, as shown in FIG. Figure 6 As shown, the connecting ring 3 comprises a circular shaft segment and tapered shaft segments integrally formed at each end of the circular shaft segment. The circular side surfaces of the tapered shaft segment are composed of multiple wedge-shaped surfaces, which better interact with the expansion strip 5 and provide support after locking. The diameter of the return spring 2 is slightly smaller than the wall thickness of the tapered shaft end of the connecting ring 3, so as not to affect the movement of the expansion strip 5.

[0031] One end of the support sleeve 4 is sleeved on the circular shaft section of the connecting ring 3. Figure 7As shown, the support sleeve 4 is a hollow tubular structure, and a plurality of annular guide grooves 15 and mounting holes 16 are processed on its wall surface. The two mounting holes 16 are located at both ends of the guide groove 15.

[0032] like Figure 5 As shown, the expansion strip 5 includes a guide plate 12 and a support plate 13 integrally formed with the guide plate 12. The top surface of the support plate 13 is located on an arc surface matching the inner wall of the pipe 10, and a flexible absorption sleeve 9 made of soft elastic material is provided thereon to achieve soft contact between the inside of the pipe 10 and the support plate 13; the two ends of the guide plate 12 on the side away from the support plate 13 are processed into inclined surfaces, and after the guide plate 12 passes through the guide groove 15, the inclined surface slides with the wedge surface of the connecting ring 3.

[0033] The small diameter end of the conical spring 6 is connected to the support plate 13 after passing through the mounting hole 16, and the diameter of its large diameter end is larger than the aperture of the mounting hole 16, so that the conical spring 6 cannot be completely separated from the mounting hole 16. The small diameter end of the conical spring 6 is bent with a hook body, and the bottom of the support plate 13 on both sides of the guide plate 12 is provided with a hook hole. The hook body passes through the hook hole to realize the connection between the conical spring 6 and the support plate 13, which facilitates the resetting of the expansion strip 5.

[0034] The return spring 2, support sleeve 4 and expansion strip 5 (conical spring 6, flexible absorption sleeve 9) constitute a support unit assembly. A plurality of support unit assemblies are mounted on the core shaft 1. Each support unit assembly is separated by a connecting ring 3. In order to meet the needs of pipe fittings 10 of different lengths, the support unit assembly can be processed into different specifications. The specifications can be divided according to length and circumferential diameter. For example, for the same diameter, two specifications of 0.5m and 1m can be designed. The number of each specification is greater than 2, that is, the needs of pipe fittings 10 of 1 to 4m can be met through assembly.

[0035] The guide pull 7 is mounted on both ends of the mandrel 1 and connected to the expansion sleeve. It includes a cylindrical end and a tapered end. The tapered end is used to expand the expansion sleeve against the inner wall of the pipe 10, keeping the conical spring 6 in tension and the return spring 2 in compression. The cylindrical end is used for clamping the processing equipment. The locking member 8 is used to lock the guide pull 7 after installation. In this embodiment, a retaining ring and nut are used to lock the guide pull 7.

[0036] During processing, the connecting ring 3, return spring 2, conical spring 6, support sleeve 4, and expansion strip 5 are installed on the core shaft 1 in sequence, and then inserted into the pipe fitting 10, and then the guide pull heads 7 are installed at both ends of the core shaft 1, and the locking nuts at both ends are tightened to make the guide pull heads 7 on both sides move toward each other along the axial direction, so that the middle expansion strips 5 and the connecting ring 3 fit tightly, and continue to tighten the nut. The expansion strip 5 expands radially under the push of the conical surface of the connecting ring 3, and then clings to the inner wall of the pipe fitting 10, thereby supporting and tightening the pipe fitting 10; the pre-tightening force of the nut is controlled by a torque wrench to achieve reliable support without damaging the workpiece.

[0037] During disassembly, the return spring 2 is initially in a compressed state, and the conical spring 6 is in a pulled state. When the nut is loosened, the guide pull head 7 and the connecting ring 3 are reset under the action of the return spring 2, and the expansion strip 5 is reset under the action of the conical spring 6, close to the outer surface of the support sleeve, and the pipe fitting 10 can be pulled out from the core shaft 1.

[0038] The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any modification and replacement based on the technical solution and inventive concept provided by the present invention should be covered by the protection scope of the present invention.

Claims

1. An internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipes, characterized by: It includes a core shaft (1) with threaded sections processed at both ends; A plurality of return springs (2) and a connecting ring (3) are sleeved on the core shaft (1), a connecting ring (3) is provided between two adjacent return springs (2), and the connecting ring (3) comprises a circular shaft segment and tapered shaft segments provided at both ends of the circular shaft segment; A support sleeve (4) sleeved on the circular shaft section of the connecting ring (3), the support sleeve (4) being a hollow tubular structure, with a wall surface thereof being processed with a plurality of annularly evenly distributed guide grooves (15) and mounting holes (16); An expansion strip (5) is arranged in the guide groove (15), and the expansion strip (5) includes a guide plate (12) and a support plate (13) installed on the top of the guide plate (12), the top surface of the support plate (13) is an arc surface matching the inner wall of the pipe (10), and the bottom ends of the guide plate (12) are processed into inclined surfaces. After the guide plate (12) passes through the guide groove (15), the inclined surface is slidably matched with the tapered shaft section of the connecting ring (3); a conical spring (6) disposed in the mounting hole (16), wherein the small-diameter end of the conical spring (6) passes through the mounting hole (16) and is connected to the support plate (13), and the large-diameter end thereof has a diameter greater than the diameter of the mounting hole (16); The return spring (2), the support sleeve (4) and the expansion strip (5) form a support unit assembly, which is sleeved on the core shaft (1), connected via a connecting ring (3), and then inserted into the pipe (10); A guide pull head (7) is sleeved on both ends of the core shaft (1), and the guide pull head (7) includes a cylindrical section and a tapered section, and the tapered section is in sliding engagement with the inclined surface of the guide plate (12) located at the end of the core shaft (1); The locking piece (8) provided on the threaded section of the core shaft (1) acts on the locking piece (8) to move the two guide pull heads (7) toward each other in the axial direction, thereby making the expansion strip (5) and the connecting ring (3) fit tightly together. The expansion strip (5) expands radially under the push of the conical shaft section of the connecting ring (3), thereby fitting tightly against the inner wall of the pipe fitting (10), thereby supporting and fastening the pipe fitting (10); at this time, the reset spring (2) is in a compressed state, and the conical spring (6) is in a stretched state. The locking piece (8) is released, and the reset spring (2) causes the guide pull heads (7) and the connecting ring (3) to move to both sides, and the conical spring (6) resets the expansion strip (5).

2. The internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipes according to claim 1, characterized in that: The core shaft (1) is provided in plurality according to the length of the pipe (10), and the support unit assembly is also provided in plurality according to the inner diameter and length of the pipe (10).

3. The internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipes according to claim 1, characterized in that: The circular side surface of the tapered shaft section of the connecting ring (3) is composed of a plurality of wedge-shaped surfaces.

4. The internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipes according to claim 1, characterized in that: A flexible absorption sleeve (9) made of soft elastic material is provided on the arc surface of the expansion strip (5).

5. The internal support fixture for cylindrical grinding of slender, thin-walled, hard and brittle material pipes according to claim 1, characterized in that: Four expansion strips (5) are provided on the supporting sleeve (4).

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