A metal tube end reduction spinning auxiliary tool

Abstract

An auxiliary tool for reducing the diameter of a metal tube end during spinning includes a mandrel, a mandrel rod, and a pull rod. The mandrel is a split structure, consisting of at least six sets of mandrel blocks forming a hollow sleeve with an outer diameter matching the inner diameter of the metal tube to be processed. The central hole of the hollow sleeve is a conical hole. The inner wall arc surface width of two opposing sets of mandrel blocks is greater than the outer wall arc surface width, forming a wedge-shaped mandrel block that can move towards the central axis of the mandrel under radial pressure. The mandrel rod is a cone matching the conical hole of the mandrel, with a threaded hole along the central axis at its large-diameter end. One end of the pull rod has an external thread that mates with the threaded hole of the mandrel, and the length of the pull rod is greater than the total length of the reduced diameter spinning section and the transition section of the metal tube to be processed. This invention achieves the goal of ensuring the stability of the reduced diameter spinning process and improving the yield of precision parts after reduced diameter spinning.

Description

Technical Field

[0001] This utility model relates to the field of metal parts spinning technology, specifically to an auxiliary tool for spinning the end of a metal tube with reduced diameter. Background Technology

[0002] In the hydraulic systems of aviation flight equipment, there are various structural forms for connecting rod-type parts. Among them, the most common is the pipe fitting and extrusion ring mating structure. In this mating structure, the two ends of the metal pipe (usually aluminum pipe) need to be reduced in diameter to facilitate insertion into the inner hole of the pipe fitting.

[0003] Currently, in the aircraft repair industry, the repair of damaged tie rod-type parts mostly involves replacing the metal tube, which raises the issue of reducing the diameter at both ends of the metal tube. Existing technology generally uses a spinning method to reduce the diameter at both ends of aluminum tubes. The specific steps are as follows: first, the aluminum tube is positioned on a conventional lathe, and one end is spun to form the outer contour. Then, the inner hole of the reduced diameter section is ground and enlarged. After one end of the aluminum tube is spun, a tapered transition surface needs to be clamped and spun at the other end, which can easily damage the already formed tapered surface. Furthermore, since this diameter reduction spinning process is completed on a conventional lathe, the processing efficiency is low. In addition, during the aforementioned diameter reduction spinning process, the material undergoes plastic deformation, generating high temperatures, which can easily lead to surface build-up (aluminum lumps), resulting in a low yield rate for precision parts produced by diameter reduction spinning. Utility Model Content

[0004] This utility model provides an auxiliary tool for reducing the diameter of a metal tube end by spinning. It aims to support the non-spinning part of the metal tube by using a split mandrel and mandrel. After the metal tube is reduced in diameter by spinning, the inner wall of the spinning part is supported by a strut with different structural forms. Then, the inner hole of the spinning part is gradually dimensionally adjusted to ensure the stability of the diameter reduction spinning process and improve the yield of precision parts.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A metal tube end-reduction spinning auxiliary tool includes a mandrel, a mandrel rod, and a pull rod;

[0007] The mandrel is a split structure, consisting of at least six sets of mandrel blocks. All the mandrel blocks are assembled to form a hollow sleeve with an outer diameter that matches the inner diameter of the metal tube to be processed. The central hole of the hollow sleeve is a conical hole. The inner wall arc surface width of the two sets of mandrel blocks arranged opposite each other is greater than the outer wall arc surface width, forming a wedge-shaped mandrel block that can move towards the central axis of the mandrel under radial pressure.

[0008] The core rod is a cone that matches the conical hole of the mandrel. The core rod is inserted into the conical hole of the mandrel to open the mandrel assembly, so that its outer wall fits and presses tightly against the inner wall of the metal tube to be processed. A threaded hole is provided at the large diameter end of the core rod along the central axis.

[0009] The pull rod is a long strip-shaped member with an external thread at one end that mates with the threaded hole of the core rod. The length of the pull rod is greater than the total length of the reduced diameter spinning part and the transition part of the metal tube to be processed.

[0010] The aforementioned metal tube end-reduction spinning auxiliary tool has a flange plate at the large-diameter end of the core rod, and the threaded hole passes through the flange plate. The outer diameter of the flange plate is smaller than the inner diameter of the metal tube end after reduction spinning.

[0011] The aforementioned metal tube end-reduction spinning auxiliary tool has a pull rod with a circular cross-section.

[0012] The aforementioned metal tube end-reduction spinning auxiliary tool also includes a set of support rods, comprising a two-part support rod, a three-part support rod, and a four-part support rod. All support rods have a clamping end and a working end, the clamping end being a cylindrical structure. The working end of the two-part support rod has two sets of support surfaces arranged opposite each other, the working end of the three-part support rod has three sets of support surfaces evenly arranged circumferentially, and the working end of the four-part support rod has four sets of support surfaces evenly arranged circumferentially. All support surfaces are arc surfaces that match the inner diameter of the metal tube's diameter reduction spinning section.

[0013] This invention provides an auxiliary tool for spinning the end diameter reduction of metal tubes. It works in conjunction with a CNC lathe and a circular arc spinning tool to achieve the spinning process of reducing the diameter of the end of metal tubes. Through the cooperation of a split mandrel and mandrel rod, it supports the non-spun parts of the metal tube, ensuring the dimensional stability of the non-spun parts during the metal tube reduction spinning process and providing reliable support for the CNC lathe to clamp the metal tube, avoiding damage to the clamping parts caused by the CNC lathe chuck. When adjusting the inner hole size and roundness of the spun part of the metal tube, the auxiliary tool for spinning the end diameter reduction of metal tubes described in this invention utilizes support rods with different structural forms. The inner hole of the spinning section is gradually sized and trimmed. Through gradual micro-plastic deformation of the inner hole material, the inner hole size is guaranteed to meet the requirements of accuracy and surface roughness. The metal tube end diameter reduction spinning auxiliary tool of this utility model has a special segmentation method for its split mandrel blocks. After the diameter reduction spinning operation is completed and the mandrel is pulled out, under the pressure of the inner wall of the metal tube on the mandrel, the two sets of wedge-shaped cross-section mandrel blocks arranged opposite each other move towards the central axis of the metal tube. They can be removed first to make way for other mandrel blocks. This ensures that all mandrel blocks can be smoothly removed from the diameter reduction end of the metal tube in sequence. Attached Figure Description

[0014] Figure 1This is a schematic diagram showing the interaction between the metal tube end-reduction spinning auxiliary tool and the metal tube to be processed.

[0015] Figure 2 yes Figure 1 Schematic diagram of the cross-sectional structure of the middle AA section;

[0016] Figure 3 This is a schematic diagram of the mandrel and mandrel mating structure;

[0017] Figure 4 This is a schematic diagram of the process of extracting the core rod and assembling the core shaft;

[0018] Figure 5 This is a schematic diagram of the end-diameter reduction spinning of a metal tube.

[0019] Figure 6 This is a schematic diagram showing the adjustment of the external dimensions of the spinning part;

[0020] Figure 7 This is a schematic diagram of a two-part strut structure;

[0021] Figure 8 yes Figure 7 K-direction view;

[0022] Figure 9 This is a schematic diagram of a three-part strut structure;

[0023] Figure 10 yes Figure 9 K-direction view;

[0024] Figure 11 This is a schematic diagram of a four-part strut structure;

[0025] Figure 12 yes Figure 11 The K-direction view.

[0026] Explanation of each label in the diagram:

[0027] 1 is a metal tube, 1-1 is the diameter reduction spinning section, and 1-2 is the transition section;

[0028] 2 is the mandrel, 2-1 is the first mandrel assembly, 2-2 is the second mandrel assembly, 2-3 is the third mandrel assembly, 2-4 is the fourth mandrel assembly, 2-5 is the fifth mandrel assembly, and 2-6 is the sixth mandrel assembly;

[0029] 3 is the core rod, 3-1 is the threaded hole, and 3-2 is the flange plate;

[0030] 4 is the tie rod;

[0031] 5 represents a spinning tool;

[0032] 6 is the strut, 6-1 is the strut at the halfway point, 6-2 is the strut at the third-third point, and 6-3 is the strut at the quarter-third point. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] See Figure 1. Figure 2 , Figure 3 This utility model provides an auxiliary tool for reducing the diameter of the end of a metal tube by spinning. It works in conjunction with a CNC lathe and a circular arc spinning tool to achieve the process of reducing the diameter of the end of a metal tube by spinning. The tool includes a mandrel 2, a mandrel 3, and a pull rod 4. The mandrel 2 is a split structure. In a preferred embodiment, the mandrel 2 is composed of six sets of mandrel blocks: a first mandrel block 2-1, a second mandrel block 2-2, a third mandrel block 2-3, a fourth mandrel block 2-4, a fifth mandrel block 2-5, and a sixth mandrel block 2-6. These six sets of mandrel blocks enclose a hollow sleeve whose outer diameter matches the inner diameter of the metal tube 1 to be processed. The central hole of the hollow sleeve is a conical hole. Among the six sets of mandrel blocks, the first mandrel block 2-1 and the fourth mandrel block 2-4 are arranged opposite each other, and the width of their inner arc surface is greater than the width of their outer arc surface. The mandrel assembly is formed by a wedge-shaped cross-section that can move towards the central axis of the mandrel under radial pressure. The mandrel 3 is a cone that matches the conical hole of the mandrel. The mandrel 3 is inserted into the conical hole of the mandrel to open the mandrel assembly, so that the outer wall of the mandrel assembly fits and presses tightly against the inner wall of the metal tube 1 to be processed. A threaded hole 3-1 is provided at the large-diameter end of the mandrel 3 along the central axis. In a preferred embodiment of the mandrel 3, a flange 3-2 is provided at the large-diameter end of the conical body of the mandrel 3. The threaded hole 3-1 passes through the flange 3-2. The outer diameter of the flange 3-2 is smaller than the inner diameter of the metal tube 1 after the end is spun. The pull rod 4 is a long strip-shaped circular cross-section rod with an external thread at one end that matches the threaded hole 3-1 on the mandrel 3. The length of the pull rod 4 is greater than the total length of the spun section 1-1 and the transition section 1-2 of the metal tube 1 to be processed.

[0035] See Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12The metal tube end-reduction spinning auxiliary tool of this utility model also includes a set of support rods 6, which include a two-part support rod 6-1, a three-part support rod 6-2, and a four-part support rod 6-3. All support rods 6 have a clamping end and a working end. The clamping end is a cylindrical structure and can be clamped and fixed by a CNC lathe center chuck. The working end of the two-part support rod has two sets of oppositely arranged support surfaces, which are arc surfaces that match the inner diameter of the diameter reduction spinning part of the metal tube 1. The working end of the support rod 6-2 is provided with three sets of support surfaces evenly arranged circumferentially. The support surfaces are arc surfaces that match the inner diameter of the metal tube's reduced diameter spinning part. The working end of the quarter support rod 6-3 is provided with four sets of support surfaces evenly arranged circumferentially. The support surfaces are arc surfaces that match the inner diameter of the metal tube's reduced diameter spinning part. In a preferred embodiment of the support rod 6, the working end of the support rod is made of a high-strength, high-hardness material, and its arc surface roughness index is not lower than Ra1.6, and the arc surface dimensional accuracy error is controlled within 0.03mm.

[0036] See Figure 4 , Figure 5 , Figure 6 When performing diameter reduction spinning on the end of a metal tube using this invention, a CNC lathe and a circular arc spinning tool can be used. The specific operation steps are as follows:

[0037] a. Metal tube clamping: Assemble the external threaded part of the pull rod 4 with the threaded hole 3-1 at the large diameter end of the core rod 3. The cone of the core rod 3 mates with the mandrel 2 and passes into the metal tube 1 to be processed. Push the core rod 3 inward through the pull rod 4. The cone of the core rod 3 opens the mandrel block of the mandrel 2, so that the outer wall of the mandrel block fits and presses tightly against the inner wall of the metal tube 1 to be processed. Then, clamp the mating part of the metal tube 1 to be processed and the mandrel 2 through the chuck of the CNC lathe. Then, remove the pull rod 4.

[0038] b. Reduction spinning: The spinning springback coefficient matching the size of the metal tube to be processed is obtained through test data. Then, the spinning number and spinning feed rate scheme are designed according to the corresponding spinning springback coefficient. Finally, the CNC lathe executes the set program to complete the reduction spinning operation.

[0039] c. Adjusting the inner diameter and roundness of the spun section: After the metal tube is spun at one end with a reduced diameter, first insert the working end of the two-part support rod 6-1 into the inner hole of the spun section 1-1 of the metal tube 1, and fix the clamping end of the two-part support rod 6-1 with the center end fixture of the CNC lathe. Apply pressure to the outer surface of the spun section 1-1 of the metal tube with the arc spun tool. Under the extrusion of the arc surface of the working end of the two-part support rod inserted into the metal tube 1, the inner hole of the spun section 1-1 of the metal tube 1 is forced to produce a small amount of plastic deformation. Then remove the two-part support rod 6-1 and replace it with the three-part support rod 6-2 and the four-part support rod 6-3 in sequence. Repeat the above steps of adjusting the inner diameter and roundness of the spun section of the metal tube until it meets the set requirements.

[0040] d. Mandrel removal: Remove the metal tube 1 from the chuck of the CNC lathe, and remove the mandrel 3 and mandrel 2 from the metal tube 1. For metal tube 1 that needs to be spun with reduced diameter at both ends, after completing the spun with reduced diameter at one end, turn the direction of the metal tube 1 and perform the spun with reduced diameter at the other end. In this operation, when the core rod 3 and the mandrel 2 are removed from the metal tube 1, firstly, the threaded end of the pull rod 4 is inserted into the metal tube 1 and screwed into the threaded hole 3-1 of the core rod 3, connecting the pull rod 4 and the core rod 3 as one unit. Then, the pull rod 4 is pulled outward, causing the cone of the core rod 3 to move outward, releasing the tension force of the core rod cone on the mandrel cone hole. Under the pressure of the inner wall of the metal tube 1 on the mandrel 2, the relatively arranged first mandrel assembly 2-1 and fourth mandrel assembly 2-4 move towards the central axis of the metal tube 1. The first mandrel assembly 2-1 and fourth mandrel assembly 2-4 can be removed from the metal tube 1 first to make way for the remaining mandrel assemblies. Then, the second mandrel assembly 2-2, the third mandrel assembly 2-3, the fifth mandrel assembly 2-5, and the sixth mandrel assembly 2-6 are removed from the reduced diameter end of the metal tube 1 in sequence.

Claims

1. A metal tube end-reduction spinning auxiliary tool, characterized in that: Includes a spindle (2), a core rod (3), and a pull rod (4); The mandrel (2) is a split structure, consisting of at least six sets of mandrel blocks. All the mandrel blocks enclose a hollow sleeve whose outer diameter matches the inner diameter of the metal tube (1) to be processed. The central hole of the hollow sleeve is a conical hole. The inner wall arc surface width of the two sets of mandrel blocks arranged opposite each other is greater than the outer wall arc surface width, forming a wedge-shaped mandrel block that can move towards the central axis of the mandrel under radial pressure. The core rod (3) is a cone that matches the conical hole of the mandrel. The core rod (3) is inserted into the conical hole of the mandrel to open the mandrel assembly, so that its outer wall fits and presses against the inner wall of the metal tube (1) to be processed. A threaded hole (3-1) is provided at the large diameter end of the core rod (3) along the central axis. The pull rod (4) is a long strip rod with an external thread at one end that mates with the threaded hole (3-1) on the core rod (3). The length of the pull rod (4) is greater than the total length of the reduced diameter spinning part (1-1) and the transition part (1-2) of the metal tube (1) to be processed.

2. The metal tube end-reduction spinning auxiliary tool according to claim 1, characterized in that: A flange (3-2) is provided at the large diameter end of the core rod (3), and the threaded hole (3-1) passes through the flange (3-2). The outer diameter of the flange (3-2) is smaller than the inner diameter of the metal tube (1) after the end is spun.

3. The metal tube end-reduction spinning auxiliary tool according to claim 2, characterized in that: The tie rod (4) is a circular cross-section rod.

4. The metal tube end-reduction spinning auxiliary tool according to claim 1, 2, or 3, characterized in that: A set of support rods (6) is also provided, which includes a two-part support rod (6-1), a three-part support rod (6-2), and a four-part support rod (6-3). All support rods (6) are provided with a clamping end and a working end. The clamping end is a cylindrical structure. The working end of the two-part support rod is provided with two sets of support surfaces arranged opposite to each other. The working end of the three-part support rod (6-2) is provided with three sets of support surfaces evenly arranged in the circumferential direction. The working end of the four-part support rod (6-3) is provided with four sets of support surfaces evenly arranged in the circumferential direction. All support surfaces are arc surfaces that match the inner diameter of the metal tube's reduced diameter spinning part.

Images