Device for enlarging inner diameter of composite pipe through balls

Abstract

The utility model discloses a device for enlarging the inner diameter of a composite pipe through balls, and belongs to the technical field of machining equipment. The device comprises an upper die assembly and a lower die assembly, the upper die assembly comprises an upper die base and an ejector rod installed on the upper die base, and the lower die assembly comprises a lower die base, a clamping sleeve fixed to the lower die base and two clamping half sleeves arranged in the clamping sleeve and used for clamping a composite pipe. A support is arranged on the lower die base, and a linear displacement sensor is arranged on the support. The diameter of the ball is matched with the target diameter of the composite pipe. According to the utility model, the ball is pushed by the ejector rod, and the ball expands the diameter of the inner pipe of the composite pipe in a cold extrusion manner, so that the problem that the diameter of the long-size and small-inner-diameter composite pipe is difficult to expand by traditional processing equipment is solved, and the device has the advantages of accurate operation, improved working efficiency and capability of protecting the structural integrity of the composite pipe; the device is suitable for expanding the inner diameter of precise pipe fittings such as stainless steel composite pipes.

Description

Technical Field

[0001] The utility model belongs to the technical field of mechanical processing equipment, and particularly relates to a device for expanding the inner diameter of a composite pipe by using balls. Background Art

[0002] Composite pipes are a new type of pipe made by bonding or welding together pipes made of the same, two, or more different materials. They offer advantages such as corrosion resistance, high strength, and low cost, and are widely used in aviation, aerospace, petroleum, chemical, water conservancy, and machinery. Stainless steel composite pipes (both the inner and outer tubes are stainless steel, bonded with a special metal adhesive) are a key category of composite pipes due to their excellent corrosion resistance and mechanical properties.

[0003] During the production and processing of stainless steel composite pipes, their inner diameter needs to be expanded to meet specific assembly or usage requirements. However, for composite pipes with long lengths, relatively small inner diameters, and small machining allowances, traditional machining equipment (such as lathes and boring machines) has obvious limitations: during lathe processing, the tool's limited penetration into the pipe makes it difficult to process long pipes as a whole, and the cutting force can easily cause pipe deformation, affecting form and position tolerances; boring machine processing requires multiple clamping, and the accumulation of positioning errors can reduce processing accuracy. In addition, the small inner diameter makes the boring bar insufficiently rigid and prone to vibration, resulting in excessive surface roughness; and cutting can damage the bonding layer between the inner and outer pipes, affecting the structural integrity of the composite pipe.

[0004] Therefore, there is an urgent need for a diameter expansion device suitable for long composite pipes with relatively small inner diameters to address the shortcomings of the existing technology. Utility Model Content

[0005] The utility model aims to solve the above problems and make up for the shortcomings of the existing technology, and provides a device for expanding the inner diameter of a composite tube by using a ball, comprising an upper die assembly and a lower die assembly; the upper die assembly comprises an upper die base and a push rod, and the push rod is fixed to the bottom of the upper die base in a vertical direction;

[0006] The lower die assembly includes a lower die base, a clamping sleeve, and two clamping half-sleeves; a base is provided at the top of the lower die base, the clamping sleeve is detachably fixed to the top of the base, the two clamping half-sleeves are disposed in the clamping sleeve, and the two clamping half-sleeves form a clamping cavity for clamping the composite pipe; the axis of the clamping cavity is collinear with the axis of the ejector rod; a bracket is provided on the lower die base, and a linear displacement sensor is provided on the bracket;

[0007] Also included are balls having a diameter that matches the target diameter size of the composite tube's inner diameter.

[0008] The linear displacement sensor is arranged on the bracket and is used to monitor the size and straightness of the expanded diameter of the composite pipe in real time.

[0009] Preferably, the upper mold assembly further includes a fixing ring and a shock-absorbing pad; the fixing ring is fixed to the bottom of the upper mold base by a first screw, the shock-absorbing pad is arranged between the fixing ring and the push rod, and the push rod is fixed to the upper mold base by the fixing ring.

[0010] Preferably, the clamping sleeve is detachably fixedly connected to the base by a second screw. The clamping half sleeve of the utility model is used to clamp the target composite pipe, facilitating the removal of the target composite pipe after diameter expansion; the clamping sleeve is used to fix the clamping half sleeve.

[0011] Preferably, a third screw is provided on the side wall of the clamping sleeve. The third screw is arranged along the radial direction of the clamping sleeve and is used to lock the clamping sleeve.

[0012] Preferably, there are multiple third screws.

[0013] Preferably, the lower die base is provided with eye screws, and the eye screws are symmetrically distributed on the lower die base.

[0014] Preferably, the material of the push rod, the upper die base and the lower die base is Q235 steel, and the material of the ball is GCr15 bearing steel.

[0015] Preferably, a recess is provided at the lower end of the push rod, and the recess matches the shape of the ball.

[0016] The ball is placed at the end of the composite tube, and the lower end of the push rod has a recess that matches the shape of the ball, which limits the other movement directions of the ball. The ball can only move downward with the push rod.

[0017] Preferably, a ball channel is provided inside the base, and the ball channel is communicated with the clamping cavity.

[0018] Beneficial effects of the utility model:

[0019] This utility model uses a push rod to push the ball, causing it to move from top to bottom within the composite tube. This movement of the ball expands the inner diameter of the composite tube through cold extrusion. The contact surface between the ball and the inner tube of the composite tube is evenly stressed, effectively ensuring high-precision machining requirements such as dimensional tolerance within ±0.02mm, straightness ≤0.1mm / m, and surface roughness Ra ≤3.2μm.

[0020] The use of the present invention can protect the structure of the composite pipe. The working process of the present invention is a cold extrusion process of the ball and the composite pipe, which is a gradual plastic deformation, avoiding the stress concentration caused by cutting processing, and can effectively protect the bonding layer between the inner pipe and the outer pipe, ensuring the structural integrity of the composite pipe. By clamping the composite pipe with a half-set and locking it with screws, the clamping is fast and the workpiece can be easily replaced, which can improve the processing efficiency. It is particularly suitable for composite pipes with a long length, a relatively small inner diameter and a small processing allowance, which makes up for the shortcomings of traditional processing equipment. In addition, the present invention is composed of conventional mechanical parts, which is easy to manufacture, install and maintain, has a low cost, and is convenient for industrial promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a three-dimensional structural diagram of the utility model.

[0022] Figure 2 This is one of the structural diagrams of the present utility model.

[0023] Figure 3 This is the second structural diagram of the present utility model.

[0024] Figure 4 It is an exploded view of the present utility model.

[0025] Figure 5 It is a structural schematic diagram of the composite pipe before diameter expansion in Example 1 of the present invention.

[0026] Figure 6 It is a schematic structural diagram of the composite pipe after diameter expansion in Example 1 of the present invention.

[0027] Figure 5 and Figure 6 The unit of length and diameter is mm.

[0028] Markings in the figure: 1 is the upper die base; 2 is the fixing ring; 3 is the first screw; 4 is the shock-absorbing pad; 5 is the push rod; 6 is the clamping sleeve; 7 is the third screw; 8 is the second screw; 9 is the eye screw; 10 is the lower die base; 11 is the ball channel; 12 is the clamping half sleeve; 13 is the ball; 14 is the linear displacement sensor; 15 is the bracket; 16 is the inner tube; 17 is the outer tube. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] Combine Figures 1 to 6As shown, the utility model includes an upper mold assembly and a lower mold assembly; the upper mold assembly includes an upper mold base 1 and a push rod 5, and the push rod 5 is fixed to the bottom of the upper mold base 1 along the vertical direction;

[0031] The lower die assembly includes a lower die base 10, a clamping sleeve 6, and two clamping half sleeves 12. The clamping sleeve 6 is detachably fixed to the top of the base. The clamping half sleeves 12 are disposed within the clamping sleeve 6. The clamping half sleeves 12 form a clamping cavity for clamping the composite pipe. The axis of the clamping cavity is collinear with the axis of the ejector rod 5.

[0032] The composite tube further comprises balls 13 , the diameter of which matches the target inner diameter of the composite tube inner tube 16 .

[0033] The upper die assembly cooperates with the hydraulic press to provide driving force, pushing the ball 13 to move in the composite tube inner tube 16 through the push rod 5. The shock absorber 4 is provided between the fixing ring 2 and the push rod 5 to cushion the impact force when the push rod 5 moves downward and avoid damage to components caused by rigid contact.

[0034] The lower die assembly is used to fix the composite pipe to ensure the stability of the diameter expansion process. The lower die base 10 is fixed to the workbench of the hydraulic press, and the workbench of the hydraulic press serves as the installation base of the lower die assembly.

[0035] The clamping sleeve 6 is fixed to the top of the base by a second screw 8. The axis of the clamping sleeve 6 is collinear with the axis of the push rod 5 to ensure the coaxiality of the push rod 5 and the composite pipe. The two clamping half sleeves 12 are symmetrically arranged in the clamping sleeve 6 to form a clamping cavity that matches the outer contour of the composite pipe and is used to tightly clamp the composite pipe. The side wall of the clamping sleeve 6 is provided with a third screw 7. After the third screw 7 is tightened along the radial direction of the clamping sleeve 6, the clamping half sleeve 12 can be locked to prevent the composite pipe from loosening during the expansion process.

[0036] In addition, the lower die base 10 is provided with a lifting eye screw 9 to facilitate the installation and transportation of the lower die base 10 .

[0037] Ball 13, the core component for expanding the diameter, matches the target diameter of the composite inner tube 16. Made of GCr15 bearing steel, it offers high strength, high wear resistance, and excellent resistance to deformation. Since ball 13 is not fixedly connected to ejector pin 5, it is easily replaced and maintained.

[0038] The fixing ring 2 is fixed to the bottom of the upper die base 1 by a first screw 3. The inner diameter of the fixing ring 2 needs to match the diameter of the ejector rod 5 to ensure the stability of the ejector rod 5 during operation.

[0039] The inner cavity of the clamping sleeve 6 is in the shape of a hollow cylinder. The size of the inner cavity of the clamping sleeve 6 matches the outer contour of the clamping half sleeve 12. The length of the clamping sleeve 6 needs to be adapted to the length of the composite pipe.

[0040] The cross-section of the clamping half sleeve 12 is semicircular, and the two clamping half sleeves 12 have the same shape.

[0041] The working process of this utility model:

[0042] 1. Fix the lower die base 10 to the workbench of the hydraulic press and the upper die base 1 to the moving crossbeam of the hydraulic press; start the hydraulic press and extend the push rod 5 into the clamping sleeve 6. Use the depth gauge to measure and adjust to ensure that the push rod 5 and the clamping sleeve 6 are coaxial, that is, the axis of the clamping cavity in the clamping sleeve 6 is collinear with the axis of the push rod 5, and then tighten the lower die base 10.

[0043] 2. Clamp the target composite tube with the two clamping half sleeves 12, place it into the clamping sleeve 6, and tighten the third screw 7 to firmly fix the composite tube.

[0044] 3. Apply lubricating oil to the inner wall of the composite tube and the surface of the ball 13 to reduce the friction resistance during the cold extrusion process and protect the inner wall of the composite tube and the ball 13.

[0045] 4. Place the ball 13 at the end of the composite pipe, start the hydraulic press, and make the upper die seat 1 drive the push rod 5 downward. The push rod 5 pushes the ball 13 to move along the inner wall of the inner tube 16 of the composite pipe. Figure 2 The dotted line in the figure represents the trajectory of the ball 13 until the ball 13 is pushed out from the bottom end of the composite tube and slides out of the ball channel 11; during the movement, the ball 13 causes the inner tube 16 of the composite tube to undergo plastic deformation through cold extrusion, and finally expands to the target size.

[0046] 5. Multiple linear displacement sensors 14 are preferably magnetostrictive. They detect displacement by magnetic field changes, converting linear mechanical displacement into an electrical signal, which is then emitted in real time. This signal is then transmitted to a monitoring screen, where the value is clearly visible. Furthermore, this signal is used to coordinate with the hydraulic press to adjust pressure, thereby varying the downward speed and achieving the required dimensional accuracy.

[0047] Example 1

[0048] like Figure 5 As shown, for a stainless steel composite pipe with a length of 650 mm and a diameter of 26 mm, the inner pipe 16 and the outer pipe 17 are bonded together using a metal-specific adhesive. The inner diameter of the inner pipe 16 needs to be expanded to a diameter of 26.5 mm. The parameters of the present invention are as follows:

[0049] Upper die base 1: Made of Q235, upper die base 1 is suitable for the moving crossbeam of the hydraulic press;

[0050] Push rod 5: material Q235, diameter 20mm, length 700mm;

[0051] Fixed ring 2: Made of Q235, the inner diameter of the fixed ring 2 matches the ejector pin 5;

[0052] Shock-absorbing pad 4: polyurethane material, thickness 5mm;

[0053] Lower die base 10: Made of Q235, the lower die base 10 is fixed to the workbench of the hydraulic press;

[0054] Clamping sleeve 6: material Q235, length 650mm;

[0055] Clamping half sleeve 12: Made of Q235, the two clamping half sleeves 12 are used to clamp the composite pipe so that the clamping cavity matches the outer diameter of the composite pipe outer tube 17;

[0056] Ball 13: GCr15 bearing steel, diameter 26.5mm.

[0057] After adjusting and installing the present invention with the hydraulic press, place the stainless steel composite tube between the two clamping halves 12 and into the clamping sleeve 6. Evenly tighten the third screw 7 on the side wall of the clamping sleeve 6 until the composite tube is securely clamped without loosening or skewing. Install the linear displacement sensor 14 on the bracket 15. Evenly apply lubricating oil to the inner wall of the composite tube, applying more lubricating oil to the ports to ensure smooth initial movement of the ball bearing 13. Immerse the ball bearing 13 in the lubricating oil until its surface is completely covered with grease.

[0058] Start cold extrusion expansion: place the ball 13 at the center of the upper end of the inner tube 16 of the composite tube; start the hydraulic press, set the downward speed to 50mm / min, and slowly move the push rod 5 downward to contact the ball 13, pushing the ball 13 to move along the inner wall of the inner tube 16 of the composite tube; during the entire process, the pressure of the hydraulic press is maintained at 5-8MPa to ensure uniform deformation; the linear displacement sensor 14 is used to monitor the extrusion change state of the composite tube in real time, and timely feedback is provided to adjust the hydraulic press pressure to control the movement speed of the ball 13 to achieve the required accuracy.

[0059] When the ball 13 is ejected from the lower end of the composite pipe, the hydraulic press is stopped and the push rod 5 is reset upward. The composite pipe is fixed during the operation. The third screw 7 is loosened and the clamping half sleeve 12 and the processed composite pipe are removed to complete the diameter expansion operation.

[0060] The structure of clamping the half sleeve 12 is convenient for installing and removing the composite pipe.

[0061] The composite pipe processed by the device of this embodiment is as follows Figure 6 As shown, the inner diameter is 26.5mm, the straightness is 0.08mm / m, the surface roughness Ra is 3.2μm, and the bonding layer between the inner tube 16 and the outer tube 17 is not peeling, which fully meets the use requirements. The finished composite sleeve is used in aircraft steering gear parts.

[0062] Before cold extrusion and expansion, the composite tube's inner and outer tubes 16 and 17 are bonded together with adhesive, leaving a 0.25mm gap between them (the diameter difference is 0.5mm). After expansion, this gap is virtually eliminated, resulting in a more secure fit. Cold extrusion creates a continuous distribution of metal fibers along the outer surface, forming a compressive stress layer that significantly exceeds the strength, hardness, and fatigue resistance of the original material. This cold extrusion process also reduces the need for mechanical cutting and shortens production cycles.

[0063] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Ordinary technicians in this field should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the scope of protection of the present invention.

Claims

1. A device for expanding the inner diameter of a composite tube by using a ball bearing, characterized in that: It comprises an upper die assembly and a lower die assembly; the upper die assembly comprises an upper die base (1) and a push rod (5), and the push rod (5) is fixed to the bottom of the upper die base (1) in a vertical direction; The lower die assembly comprises a lower die base (10), a clamping sleeve (6), and two clamping half sleeves (12); a base is provided at the top of the lower die base (10), the clamping sleeve (6) is fixed to the top of the base, the two clamping half sleeves (12) are provided in the clamping sleeve (6), and the two clamping half sleeves (12) form a clamping cavity for clamping the composite pipe; the axis of the clamping cavity is collinear with the axis of the ejector rod (5); a bracket (15) is provided on the lower die base (10), and a linear displacement sensor (14) is provided on the bracket (15); The invention also comprises a ball (13), the diameter of which matches the target diameter size of the inner tube (16) of the composite tube.

2. The device for expanding the inner diameter of a composite tube by using balls according to claim 1, characterized in that: The upper die assembly further comprises a fixing ring (2) and a shock-absorbing pad (4); the fixing ring (2) is fixed to the bottom of the upper die base (1) via a first screw (3); the shock-absorbing pad (4) is arranged between the fixing ring (2) and the ejector rod (5); and the ejector rod (5) is fixed to the upper die base (1) via the fixing ring (2).

3. The device for expanding the inner diameter of a composite tube by using balls according to claim 1, characterized in that: The clamping sleeve (6) is detachably fixedly connected to the base via a second screw (8).

4. The device for expanding the inner diameter of a composite tube by using balls according to claim 1, characterized in that: A third screw (7) is provided on the side wall of the clamping sleeve (6), and the third screw (7) is arranged along the radial direction of the clamping sleeve (6). The third screw (7) is used to lock the clamping sleeve (6).

5. The device for expanding the inner diameter of a composite tube by using balls according to claim 1, characterized in that: The lower die base (10) is provided with eyebolts (9), and the eyebolts (9) are symmetrically distributed on the lower die base (10).

6. The device for expanding the inner diameter of a composite tube by using balls according to claim 1, characterized in that: The material of the push rod (5), the upper die base (1) and the lower die base (10) is Q235 steel, and the material of the ball (13) is GCr15 bearing steel.

7. The device for expanding the inner diameter of a composite tube by using balls according to claim 1, characterized in that: A recess is provided at the lower end of the push rod (5), and the recess matches the shape of the ball (13).

8. The device for expanding the inner diameter of a composite tube by using balls according to claim 1, characterized in that: A ball channel (11) is provided inside the base, and the ball channel (11) is communicated with the clamping cavity.

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