Tool for machining outer circle of large-specification stainless steel pipe fitting

Abstract

The utility model provides a large-specification stainless steel pipe fitting outer circle machining tool which comprises a lead screw, a fixed end cover and a locking nut. Central holes are formed in two ends of the screw rod body; the length of the lead screw body is larger than the axial length of the workpiece, and the two ends of the lead screw body extend out of the two ends of the workpiece. The two ends of the workpiece are concentrically positioned and adaptively provided with the fixed end covers, end cover center holes formed in the fixed end covers and the lead screw are concentrically positioned and adaptively installed, the end cover center holes transfer the center of the workpiece to the centers of the fixed end covers, and the outer threads at the two ends of the lead screw are screwed and adaptively provided with the locking nuts which clamp the fixed end covers of the workpiece. Therefore, the workpiece and the lead screw are concentrically locked, fastened and connected into a whole. According to the utility model, the technical problem that a large-specification stainless steel pipe fitting workpiece cannot be clamped and machined on an ME1332A cylindrical grinding machine at high precision is solved, the machining precision grade can reach IT5 and IT7, the surface roughness is less than 0.2 mu m, and high-precision, high-efficiency and low-cost machining of the outer circle of the large-specification stainless steel pipe fitting workpiece is realized.

Description

Technical Field

[0001] This utility model belongs to the field of machine tool metal processing fixture technology, specifically relating to a fixture for machining the outer diameter of large-size stainless steel pipe fittings. Background Technology

[0002] In the field of machining, stainless steel pipe fittings are mainly used in fluid transmission, heat exchange pipelines and other scenarios. Stainless steel has good oxidation resistance, heat resistance, toughness and wear resistance, and is considered a difficult material to machine in grinding.

[0003] The ME1332A cylindrical grinder has advantages in machining some small-sized parts with center holes, but it cannot perform center-positioning machining on some large-diameter, long stainless steel pipes. Furthermore, the large weight and length of these stainless steel pipes generate significant cutting forces during grinding, which the rigidity of the ME1332A grinder may not be able to withstand, leading to increased machine vibration and affecting machining accuracy and surface quality. In addition, longer workpieces result in even greater vibration during grinding, further impacting machining accuracy. Therefore, the following improvement technical solutions are proposed. Utility Model Content

[0004] The technical problem solved by this utility model is to provide a machining fixture for the outer diameter of large-size stainless steel pipe fittings, which adopts the method of transferring the center of the stainless steel pipe fitting workpiece to the center of the lead screw fixed end cap, thereby solving the technical problem that large-size stainless steel pipe fitting workpieces cannot be clamped and machined with high precision on the ME1332A cylindrical grinding machine.

[0005] The technical solution adopted in this utility model is as follows: A tooling for machining the outer diameter of a large-specification stainless steel pipe fitting, the tooling including a lead screw, a fixed end cap, and a locking nut; the two ends of the lead screw body are respectively provided with center holes on their axial end faces; the length of the lead screw body is greater than the axial length of the workpiece, and the two ends of the lead screw body extend from the two ends of the workpiece; the extended ends of the lead screw body are provided with external threads; the two ends of the workpiece are concentrically positioned and fitted with the fixed end cap, the fixed end cap is provided with a mandrel hole, the mandrel hole of the end cap is concentrically positioned and fitted with the lead screw, the mandrel hole transfers the center of the workpiece to the center of the fixed end cap; the external threads at both ends of the lead screw are respectively screwed to fit and fitted with locking nuts, the locking nuts clamp the fixed end cap of the workpiece, thereby concentrically locking and fastening the workpiece and the lead screw into one piece.

[0006] The above technical solution further includes a gasket, which is disposed between the outer end face of the fixed end cap and the inner end face of the locking nut.

[0007] In the above technical solution, further: the outer diameter of the gasket is larger than the inner diameter of the end cap core hole, and the gap of the gasket center hole is adapted to the lead screw body.

[0008] In the above technical solution, further: the fixed end cap is a T-shaped structure, and the large diameter end diameter φ1 of the fixed end cap is smaller than the outer diameter of the workpiece, while the large diameter end diameter φ1 of the fixed end cap is larger than the inner diameter of the workpiece.

[0009] In the above technical solution, further: the small diameter end diameter φ2 of the fixed end cap is concentrically positioned and adapted to the inner hole of the workpiece, and the adaptation gap is no greater than 0.02mm.

[0010] In the above technical solution, the fixed end cap and the lead screw are both made of 45 steel with surface oxidation treatment.

[0011] Advantages of this utility model compared to the prior art:

[0012] 1. This utility model can effectively perform precision machining on the outer circle of large-size stainless steel pipe fittings, with a precision level of IT5 or IT7 and a surface roughness of <0.2μm.

[0013] 2. The extra-long rod body of this utility model allows for the transfer of the workpiece positioning center through a fixed end cap, enabling high-precision, high-efficiency, and low-cost processing of the outer diameter of large-sized stainless steel pipe workpieces.

[0014] 3. The gasket design of this utility model prevents end face damage, extends tooling life, reduces maintenance and replacement costs, and improves tooling utilization by adjusting the gasket thickness to suit different workpieces.

[0015] 4. The gap between the fixed end cap and the inner hole of the workpiece is ≤0.02mm, which significantly improves the coaxiality of the outer circle and the surface quality, meets the requirements of high-precision machining, shortens the clamping time, reduces wear, and extends the tooling life; the maintenance cost is sharply reduced, the vibration suppression and cutting force bearing capacity are improved, and the defect rate is reduced.

[0016] 5. The material selection and oxidation treatment of this utility model form a high-strength tooling substrate and a low-cost oxide layer, balancing performance and cost, making it suitable for mass production. The oxide layer replaces the plating layer, is pollution-free, improves corrosion resistance, and extends the tooling life. Attached Figure Description

[0017] Figure 1 This is a diagram showing the working state of the tooling of this utility model for clamping workpieces;

[0018] Figure 2 This utility model Figure 1 The main view of the lead screw in the middle;

[0019] Figure 3 This utility model Figure 1 The front view of the fixed end cap;

[0020] Figure 4 for Figure 3Sectional view AA of the fixed end cap;

[0021] In the diagram: 1-workpiece, 2-lead screw, 201-external thread, 3-fixed end cap, 301-end cap core hole, 4-locking nut, 5-washer. Detailed Implementation

[0022] The following will refer to the appendix in the embodiments of this utility model. Figure 1-4 The technical solutions in the embodiments of this utility model are clearly and completely described herein. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0023] (like Figure 1 (As shown) A tooling for machining the outer diameter of a large-size stainless steel pipe fitting, the tooling including a lead screw 2, a fixed end cap 3, and a locking nut 4.

[0024] Taking the machining of the outer diameter of a φ75×4mm stainless steel pipe workpiece 1 as an example, this utility model provides that, during clamping, the end faces of both ends of the lead screw 2 are respectively provided with center holes. These center holes are used for positioning the two ends of the lead screw 2 on the centers of the ME1332A cylindrical grinding machine, ensuring the machining accuracy of the workpiece 1.

[0025] (combination) Figure 2 The length of the lead screw 2 is greater than the axial length of the workpiece 1, and both ends of the lead screw 2 extend from both ends of the workpiece 1 to form a "cantilever" support, which avoids interference with the tooling when machining the outer circle of the workpiece 1, and ensures sufficient machining allowance. It is suitable for machining large-specification pipe workpieces 1.

[0026] The lead screw 2 has an external thread 201 at its extended end; the external thread 201 at the extended end is used to tighten the locking nut 4 described later. The two ends of the workpiece 1 are concentrically positioned and fitted with fixed end caps 3, the outer circle of the fixed end caps 3 is positioned with the inner hole of the workpiece 1, ensuring that the coaxiality of the outer circle of the workpiece 1 meets the requirements after machining.

[0027] (like Figure 3 , Figure 4 As shown, the fixed end cap 3 has an end cap core hole 301, which is concentrically positioned and fitted with the lead screw 2. The end cap core hole 301 transfers the center of the workpiece 1 to the center of the fixed end cap 3. The end cap core hole 301 and the lead screw 2 have a clearance fit (H7 / g6), and the positioning error is ≤0.03mm.

[0028] The lead screw 2 has external threads 201 at both ends, and locking nuts 4 are screwed on to fit. The locking nuts 4 clamp the fixed end cap 3 of the workpiece 1, thereby concentrically locking and fixing the workpiece 1 and the lead screw 2 together. The locking nuts 4 clamp the fixed end cap 3 to form a "tightening at both ends" structure, which concentrically positions and constrains the workpiece 1.

[0029] After clamping workpiece 1, this utility model tooling can effectively perform precision machining on the outer diameter of large-diameter stainless steel pipe workpiece 1, achieving an accuracy level of IT5 or IT7 and a surface roughness of <0.2μm. The three-stage concentric transfer mechanism ensures that the coaxiality of the outer diameter of workpiece 1 after machining is ≤0.05mm. The extra-long lead screw 2 effectively avoids machining interference.

[0030] (combination) Figure 1 In the above embodiments, it is further included that: a gasket 5 is disposed between the outer end face of the fixed end cap 3 and the inner end face of the locking nut 4.

[0031] It should be noted that by adjusting the thickness of the shim 5, the fixed end cap 3 and the locking nut 4 are ensured to be fully fitted, avoiding uneven locking force due to end face gaps. This also reduces workpiece eccentricity caused by non-parallel end faces, and the coaxiality error of the outer diameter after machining can be reduced by 30% to 50%. By replacing the shims 5 with different thicknesses or materials, the preload of the locking nut 4 can be finely adjusted. For example, for high-strength stainless steel pipe fittings (such as 316L), elastic shims (such as spring steel) can be used to achieve buffered locking, avoiding workpiece deformation due to overload. As a consumable part, the shim 5 can isolate the locking nut 4 from direct friction with the fixed end cap 3. After the shim 5 wears out, only the shim 5 needs to be replaced; there is no need to repair or replace the fixed end cap 3, reducing tooling maintenance costs.

[0032] In the above embodiments, further: the outer diameter of the gasket 5 is larger than the inner diameter of the end cap core hole 301, and the gap of the center hole of the gasket 5 is adapted to the body of the lead screw 2.

[0033] It should be noted that the outer diameter of the gasket 5 is larger than the inner diameter of the end cap core hole 301, ensuring that the gasket 5 completely covers the end face of the fixed end cap 3. The tightening force of the locking nut 4 is evenly transmitted to the entire end face of the fixed end cap 3 through the gasket 5, preventing deformation or crushing of the edge of the end cap core hole 301 of the fixed end cap 3 due to local pressure concentration. Actual measurements show that the full-coverage design of the gasket 5 can reduce the maximum stress on the end face of the fixed end cap 3 by 40% to 60% (e.g., from 120MPa to 50MPa), extending the service life of the fixed end cap 3.

[0034] (like Figure 3 , Figure 4As shown in the above embodiment, the fixed end cover 3 is a T-shaped structure. The large diameter end diameter φ1 of the fixed end cover 3 is smaller than the outer diameter of the workpiece 1, while the large diameter end diameter φ1 of the fixed end cover 3 is larger than the inner diameter of the workpiece 1.

[0035] It should be noted that the large-diameter end diameter φ1 of the fixed end cap 3 is smaller than the outer diameter of the workpiece 1 to avoid interference during the machining of the outer diameter of the workpiece 1. The outer diameter of the large-diameter end of the T-shaped structure forms a "labyrinth seal" with the inner hole of the workpiece 1, preventing chips and coolant from entering.

[0036] In the above embodiments, further: the small diameter end diameter φ2 of the fixed end cap 3 is concentrically positioned and adapted to the inner hole of the workpiece 1, and the adaptation gap is no greater than 0.02mm.

[0037] It should be noted that the small-diameter end diameter φ2 and the inner hole of workpiece 1 are fitted with a high-precision fit (e.g., H7 / h6) with a clearance ≤0.02mm to ensure that the fixed end cap 3 and workpiece 1 are concentrically positioned. After machining, the coaxiality error of the outer circle of workpiece 1 can be controlled within 0.03mm. The high-precision fit can reduce radial runout caused by eccentricity during grinding and improve surface finish. The small clearance (≤0.02mm) can limit the relative movement between the fixed end cap 3 and workpiece 1, absorb cutting vibration energy, and reduce chatter defects.

[0038] In the above embodiments, the fixed end cap 3 and the lead screw 2 are both made of 45 steel with surface oxidation treatment.

[0039] It should be noted that 45 steel has a tensile strength ≥600MPa and a yield strength ≥355MPa, capable of withstanding cutting and clamping forces during machining. Compared to alloy steels (such as 40Cr and GCr15), 45 steel reduces material costs by approximately 30%–50%, making it suitable for mass production. After oxidation treatment, the surface hardness can reach HV400–500 (substrate hardness HV200–250), improving wear resistance by 2–3 times. The cost of oxidation treatment is only 1 / 5 to 1 / 3 of that of chrome plating or nitriding, resulting in a high overall cost-performance ratio. The 45 steel substrate can withstand multiple surface treatments, extending the overall tooling life to three times that of traditional coatings, thus extending tooling life.

[0040] As can be seen from the above description, this utility model can effectively perform precision machining on the outer circle of large-sized stainless steel pipe workpiece 1, with a precision level of IT5 or IT7 and a surface roughness of <0.2μm.

[0041] The extra-long rod body of the lead screw 2 of this utility model transfers the positioning center of the workpiece 1 through the fixed end cap 3, thereby realizing high-precision, high-efficiency, and low-cost processing of the outer circle of the large-specification stainless steel pipe workpiece 1.

[0042] The gasket 5 of this utility model is designed to prevent end face damage, extend tooling life, reduce maintenance and replacement costs, and adapt to different workpieces 1 by adjusting the thickness of the gasket 5, thereby improving tooling utilization.

[0043] The gap between the fixed end cap 3 and the inner hole of the workpiece 1 is ≤0.02mm, which significantly improves the coaxiality of the outer circle and the surface quality, meets the requirements of high-precision machining, shortens the clamping time, reduces wear, and extends the tooling life; the maintenance cost is sharply reduced, the vibration suppression and cutting force bearing capacity are improved, and the defect rate is reduced.

[0044] The material selection and oxidation treatment of this invention form a high-strength tooling substrate and a low-cost oxide layer, achieving a balance between performance and cost, making it suitable for mass production; the oxide layer replaces the plating layer, is pollution-free and improves corrosion resistance, extending the tooling's lifespan.

[0045] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0046] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the scope of protection of the present utility model. Any modifications and equivalent substitutions made within the spirit and principles of the present utility model are included within the scope of protection of the present utility model.

Claims

1. A tooling for machining the outer diameter of large-diameter stainless steel pipe fittings, characterized in that: The tooling includes a lead screw (2), a fixed end cap (3), and a locking nut (4); the lead screw (2) has a center hole on the shaft end face at both ends; the length of the lead screw (2) is greater than the axial length of the workpiece (1), and both ends of the lead screw (2) extend from both ends of the workpiece (1); the extended ends of the lead screw (2) are provided with external threads (201); the fixed end cap (3) is concentrically positioned and fitted at both ends of the workpiece (1), and the fixed end cap (3) is provided with external threads (201). The end cap has a core hole (301), which is concentrically positioned and fitted with the lead screw (2). The core hole (301) transfers the center of the workpiece (1) to the center of the fixed end cap (3). The external threads (201) at both ends of the lead screw (2) are screwed with locking nuts (4) to fit and install. The locking nuts (4) clamp the fixed end cap (3) of the workpiece (1), thereby concentrically locking and fastening the workpiece (1) and the lead screw (2) into one.

2. The tooling according to claim 1, characterized in that: It also includes a gasket (5), which is disposed between the outer end face of the fixed end cap (3) and the inner end face of the locking nut (4).

3. The tooling according to claim 2, characterized in that: The outer diameter of the gasket (5) is larger than the inner diameter of the end cap core hole (301), and the gap of the center hole of the gasket (5) is adapted to the rod body of the lead screw (2).

4. The tooling according to claim 1 or 2, characterized in that: The fixed end cap (3) has a T-shaped structure. The large diameter end diameter φ1 of the fixed end cap (3) is smaller than the outer diameter of the workpiece (1), while the large diameter end diameter φ1 of the fixed end cap (3) is larger than the inner diameter of the workpiece (1).

5. The tooling according to claim 4, characterized in that: The small diameter φ2 of the fixed end cap (3) is concentrically positioned and adapted to the inner hole of the workpiece (1), and the fitting gap is no greater than 0.02mm.

6. The tooling according to claim 5, characterized in that: Both the fixed end cap (3) and the lead screw (2) are made of 45 steel with surface oxidation treatment.

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