A high-precision plug-and-pull resistant TYPE-C shell drawing process

Abstract

The present invention discloses a high-precision plug-and-pull resistant TYPE-C shell drawing process, which comprises the following steps: firstly, annealing a tube to soften the tube; then drawing the treated tube into a transitional elliptical tube; then drawing the transitional elliptical tube multiple times to obtain an oblate tube; and then annealing the oblate tube again. Then, an ammonia decomposition atmosphere obtained by completely decomposing liquid ammonia through a heated catalyst layer is fed into the annealing furnace. The temperature of the annealing furnace is set at 450-550°C, the annealing time is 4-8 hours, and the concentration of undecomposed ammonia in the ammonia decomposition atmosphere is set at 50-100×10 ‑6 After annealing, a nitrided layer with a thickness of 1-3 μm is formed on the surface of the oblong tube. The oblong tube with the nitrided layer is then subjected to at least two passes of wall-reducing drawing to obtain a finished product. This invention improves surface hardness while maintaining overall softness, resolving the conflict between interface material hardness and dimensional accuracy control.

Description

Technical Field

[0001] The present invention relates to the technical field of connector manufacturing, and in particular to a high-precision plug-and-pull resistant TYPE-C shell drawing process. Background Art

[0002] Due to its inherent characteristics, the Type-C interface is prone to poor contact and a high failure rate. Analysis of the causes of poor contact in the Type-C interface reveals that, in addition to poor product quality and design, insufficient housing material properties, particularly hardness, and large dimensional tolerances are the primary contributing factors. If the housing material is too soft, the interface will loosen and expand during use, leading to poor contact. However, if the housing material is too hard, the housing will rebound significantly during molding, making dimensional accuracy difficult to control. Furthermore, excessively hard housing material can damage the molding die.

[0003] When manufacturing USB TYPE-C connectors on the market, due to formability considerations, austenitic stainless steels with good plasticity, such as 316 stainless steel, are generally selected and formed through a secondary stretching process. Annealing and softening treatment is performed before the final air-drawing process to ensure the accuracy of the final connector. Since austenitic stainless steel cannot be hardened through heat treatment, it can only be improved through work hardening. The deformation during the final air-drawing process is too small, with only a 0.01mm dimensional change in the thickness direction. This insufficient work hardening results in the connector housing material having low hardness, making it susceptible to deformation during subsequent use, leading to poor contact. Balancing the contradiction between material hardness and dimensional accuracy is a challenge faced in connector housing manufacturing.

[0004] A previous patent (application number CN202220915179) provided a plug-resistant Type-C connector. By installing a corresponding reinforcement plate in the wider position between the upper and lower rows of terminals, it can effectively ensure the overall strength of the tongue plate, thereby improving product quality and extending service life. However, this solution changes the structure of the interface and increases manufacturing difficulty. Summary of the Invention

[0005] The present invention aims to solve the above technical problems and provide a high-precision plug-and-pull resistant TYPE-C shell drawing process, which can improve the surface hardness while maintaining the overall softness, and solve the contradiction between the hardness of the interface material and the dimensional accuracy control.

[0006] In order to solve the above technical problems, the present invention provides a high-precision plug-and-pull resistant TYPE-C shell drawing process, comprising the following steps:

[0007] Step 1) annealing the pipe to soften it;

[0008] Step 2) drawing the treated pipe into a transition elliptical pipe;

[0009] Step 3) Drawing the transition elliptical tube multiple times to obtain an oblate tube;

[0010] Step 4) The oblate tube is annealed again. The ammonia decomposition atmosphere obtained by completely decomposing liquid ammonia through the heated catalyst layer is fed into the annealing furnace. The temperature of the annealing furnace is set at 450-550°, the annealing time is 4-8 hours, and the concentration of undecomposed ammonia in the ammonia decomposition atmosphere is set at 50-100×10 -6 After annealing, a nitriding layer is formed on the surface of the oblate tube with a thickness of 1-3 μm;

[0011] Step 5) The flat round tube with the nitrided layer is subjected to at least two passes of wall-reducing drawing to obtain a finished product.

[0012] Furthermore, in step 4), the temperature of the annealing furnace is set to 500°.

[0013] Furthermore, in step 4), the concentration of undecomposed ammonia in the ammonia decomposition atmosphere is set to 80×10 -6 .

[0014] Furthermore, in step 4), the annealing time is 7 hours.

[0015] Furthermore, in step 4), a plurality of oblate tubes are mounted in a fixing rack, and the fixing rack is placed in an annealing furnace for batch annealing of the oblate tubes, with gaps being provided between adjacent oblate tubes.

[0016] Furthermore, the fixed frame includes a fixed plate and a movable plate arranged in parallel, two sliding sleeves are provided on the fixed plate, two sliding rods are provided on the movable plate, the two sliding sleeves and the two sliding rods cooperate with each other and one end of the sliding rod is extended into the sliding sleeve, and a locking screw is provided on the surface of the sliding sleeve, which is used to fix the relative position between the sliding sleeve and the sliding rod. The fixed plate, movable plate, sliding rod and sliding sleeve cooperate to form a rectangular frame structure, and card grooves are provided on the two opposite surfaces of the fixed plate and the movable plate.

[0017] Furthermore, it also includes a placement seat, on which a placement pad is provided, and on which a placement groove for placing the oblate tube is provided, and the fixed plate and the movable plate are provided on both sides along the length direction of the placement groove.

[0018] Furthermore, the number of the placed pads is 2, which are a fixed pad and a movable pad. The fixed pad is fixedly mounted on the base plate, and the movable pad is arranged on the base plate through a sliding rail. The fixed pad is provided with a first limiting slot on the side away from the movable pad, and the movable pad is provided with a second limiting slot on the side away from the fixed pad. The fixed plate and the movable plate are respectively arranged in the first limiting slot and the second limiting slot.

[0019] Furthermore, a positioning hole is provided in the first limiting slot, and a positioning pin is provided at the bottom of the fixing plate. The positioning hole cooperates with the positioning pin to define the position of the fixing plate.

[0020] Furthermore, lifting handles are provided on the top of the fixed plate and the movable plate.

[0021] Beneficial effects of the present invention:

[0022] Based on the existing flat tube production process, this invention adjusts the annealing process, replacing the original single-function stainless steel soft annealing with a soft annealing plus a thin layer of nitriding. This results in a fully softened base and a hardened surface. This process requires minimal changes to the overall process, is simple to operate, and has low modification costs. The improved heat treatment not only maintains the original softening effect, but also creates a 1-3 μm nitrided layer on the outer layer of the stainless steel tube, increasing material hardness, making the interface more wear-resistant, improving plugging and unplugging resistance, and extending service life. Most importantly, it prevents poor contact while maintaining a soft base, which essentially does not affect the forming of the shell tube. This allows for excellent control of dimensional accuracy and surface finish, thus satisfying the conflicting requirements of interface material hardness and dimensional accuracy control. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the cross-sectional structure of the oblate tube after annealing of the present invention;

[0024] Figure 2 It is a schematic diagram of the matching structure of the fixing frame and the fixing seat of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of the present invention in which an oblate tube is placed on a fixed seat;

[0026] Figure 4 This is a schematic diagram of the structure of the present invention in which the fixing frame cooperates with the fixing seat to clamp the oblate tube;

[0027] Figure 5 It is a schematic diagram of the overall structure of the fixing frame of the present invention after clamping the oblate tube. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0029] An embodiment of the high-precision plug-and-pull resistant TYPE-C shell drawing process of the present invention, the technical solution adopted by the present invention is to use ammonia decomposition atmosphere annealing during the stainless steel annealing process, and control the decomposition degree of the ammonia decomposition atmosphere so that a small amount of residual ammonia in the ammonia decomposition atmosphere enters the annealing furnace; specifically, the ammonia decomposition atmosphere is composed of H2 and N2. During annealing, the ammonia decomposition atmosphere can protect the chromium-nickel austenitic stainless steel pipe to achieve good bright and non-oxidation effects. The ammonia decomposition atmosphere is obtained by completely decomposing liquid ammonia through a heated catalyst layer. The decomposition degree of liquid ammonia depends on the appropriate reaction temperature and catalyst. If the decomposition rate is low, the ammonia decomposition atmosphere often contains a small amount of residual ammonia. If these residual ammonia enters the annealing furnace, it will cause thermal decomposition and produce trace amounts of atomic nitrogen, causing the metal to nitride, resulting in the stainless steel pipe becoming brittle and scrapped. Therefore, during bright annealing of stainless steel products, the ammonia decomposition rate is increased as much as possible, and refining (purification) measures are taken after ammonia decomposition to ensure the purity of the ammonia decomposition atmosphere and the quality of the stainless steel pipe. However, the present invention takes the opposite approach and reduces the purity of the ammonia decomposition atmosphere, allowing a small amount of residual ammonia to enter the annealing furnace, where it is pyrolyzed to produce a trace amount of atomic nitrogen, causing nitriding on the pipe surface. In addition, by shortening the annealing time and controlling the thickness of the nitrided layer to 1-3 μm, the surface is hardened while the annealing softens. This state does not affect the subsequent wall reduction drawing, and can also ensure drawing accuracy, surface friction resistance, good finish, and more stable process control.

[0030] The specific process steps are as follows: first, the tube is annealed to soften the tube, and no atmosphere is added during annealing; then, the treated tube is drawn into a transitional elliptical tube; the transitional elliptical tube is drawn multiple times to obtain an oblate tube; the oblate tube 1 is annealed again, and the ammonia decomposition atmosphere obtained by completely decomposing liquid ammonia through a heated catalyst layer is sent into the annealing furnace. The temperature of the annealing furnace is set to 500°, and the annealing time is 7 hours, which is significantly reduced compared to the existing annealing time of 12-24 hours. The concentration of undecomposed ammonia in the ammonia decomposition atmosphere is set to 80×10 -6 After annealing, a nitriding layer 2 is formed on the surface of the flat tube. By controlling the temperature, time and residual ammonia, a nitriding layer with a surface thickness of 1-3 μm is obtained. Figure 1 As shown, the flat round tube with the nitriding layer is subjected to two passes of wall reduction drawing to ensure the appearance quality of the weld and the stability of the final finished product drawing to obtain the finished product.

[0031] Through the processing technology of the present invention, the size and shape accuracy of the produced shell are:

[0032] Pipe wall thickness uniformity <0.005mm Pipe width deviation <0.03mm Shell verticality deviation <0.03mm External surface finish <0.004mm Internal surface finish <0.004mm

[0033] To address the problem of balancing the strength and dimensional control of the currently used TYPE-C interface shell material, the present invention utilizes the annealing process that already exists in the interface production process to bright anneal the stainless steel tube in an ammonia decomposition atmosphere, while controlling the degree of ammonia decomposition in the atmosphere to slightly nitride the surface of the stainless steel tube, thereby improving the hardness of the stainless steel material. Since the nitride layer is very thin, the substrate remains soft and does not affect subsequent drawing deformation, thereby resolving the contradiction between the hardness of the interface material and the dimensional accuracy control.

[0034] In order to better form a nitriding layer on the surface of the oblate tube, multiple oblate tubes are installed in a fixed rack, and the fixed rack 3 is placed in an annealing furnace to anneal the oblate tubes in batches. A gap is set between adjacent oblate tubes. Figure 5 As shown, the oblate tubes are suspended by a fixing frame, and there are gaps between each oblate tube, so that a nitriding layer can be formed on the entire outer surface of the oblate tube during annealing.

[0035] Specifically, refer to Figures 2 to 5 As shown, the fixed frame includes a fixed plate 4 and a movable plate 5 arranged in parallel. Two sliding sleeves 6 are provided on the fixed plate, and two sliding rods 7 are provided on the movable plate. The two sliding sleeves cooperate with the two sliding rods in pairs, and one end of the sliding rod extends into the sliding sleeve. A locking screw 8 is provided on the surface of the sliding sleeve. The locking screw is used to fix the relative position between the sliding sleeve and the sliding rod. The fixed plate, the movable plate, the sliding rod and the sliding sleeve cooperate to form a rectangular frame structure. The fixed plate and the movable plate are provided with a card slot 9 on the two opposite surfaces. The two sliding rods extend into the two sliding sleeves. While being able to slide axially, they limit the position of the fixed plate and the movable plate. They can only move relative to each other in the axial direction. After moving into place, they are fixed by locking screws to achieve the stability of the frame. The oblong tube is placed between the fixed plate and the movable plate. The fixed plate and the movable plate move close to each other. The card slot covers on the two plates are provided at both ends of the oblong tube, so that the oblong tube cannot fall, and the structure is suspended. The slot is a profiled structure that imitates the end structure of the flat round tube, with good positioning effect. The slot is a structure that gradually becomes smaller from the slot mouth to the bottom of the slot. The size of the slot bottom is the same as or slightly larger than the size of the flat round tube end.

[0036] In order to better place the oblate round tubes, a placing seat 10 is also designed, on which a placing pad 11 is provided, and on which a placing groove 12 for placing the oblate round tubes is provided. The fixed plate and the movable plate are arranged on both sides along the length direction of the placing groove. When in use, the fixed frame is placed on the placing seat, and the oblate round tubes are placed in the placing groove of the placing seat. Then the fixed frame is pushed to make the fixed plate and the movable plate move closer to each other, forming an effect of clamping the oblate round tubes. Finally, the oblate round tubes positioned in the placing grooves can enter the card slots at one time, and the operation is simple and reliable.

[0037] Specifically, there are two pads, one fixed pad 13 and one movable pad 14. The fixed pad is fixedly mounted on a base plate 15, and the movable pad is mounted on the base plate via a sliding track 16. A first limiting slot 17 is provided on the side of the fixed pad away from the movable pad, and a second limiting slot 18 is provided on the side of the movable pad away from the fixed pad. The fixed plate and the movable plate are respectively disposed within the first and second limiting slots. A positioning hole is provided within the first limiting slot, and a positioning pin is provided at the bottom of the fixed plate. The positioning hole and the positioning pin cooperate to define the position of the fixed plate. Lifting handles 21 are also provided on the top of the fixed plate and the movable plate for easy lifting and picking.

[0038] When using, refer to Figure 2 As shown, the fixed frame is placed on the placement seat, wherein the fixed plate is placed in the first limit slot, and the positioning pin is inserted into the positioning hole to limit the horizontal movement position, and the movable plate can be moved arbitrarily and placed in the second limit slot. Here, the limit pin and the limit hole can be omitted, and it can be directly placed in the second limit slot. Of course, limit pins and limit holes can also be set. After setting, there is no misalignment problem between the slots and the placement grooves in a straight line, and the alignment accuracy is higher; then the movable pad is pulled in the direction away from the fixed pad until the movable pad is limited, and then the position of the movable pad is locked, and the position of the movable pad is fixed. The fixed frame is pulled open, and then the oblong tube is placed in the placement grooves of the fixed pad and the movable pad. Since the movable pad is moved to the far end, both ends of the oblong tube can be placed in the placement groove without interfering with the fixed plate and the movable plate. After the placement is completed, the lock of the movable pad is released, and the movable pad is pushed toward the fixed pad. The movable plate is pushed to move synchronously. The movement of the movable plate cooperates with the fixed plate to clamp the placed oblong tube. After the movable plate cannot move, the oblong tube is clamped in the card slot. Then the locking screw is locked, and the position of the sliding sleeve and the sliding rod is fixed, and they cannot be extended or moved, achieving an overall fixing effect. Then, the handle is removed for annealing. The operation is simple, and there will be no product contact interference during the annealing process, ensuring the coverage rate of the nitriding layer on the surface of the oblong tube.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A high-precision plug-and-pull resistant TYPE-C shell drawing process, characterized in that: The following steps are involved: Step 1) Annealing the tube to soften it; Step 2) Drawing the processed tube into a transition elliptical tube; Step 3) Drawing the transition elliptical tube multiple times to obtain an oblate tube; Step 4) The oblate tube is annealed again. The ammonia decomposition atmosphere obtained by completely decomposing liquid ammonia through the heated catalyst layer is sent into the annealing furnace. The temperature of the annealing furnace is set at 450-550°, the annealing time is 4-8 hours, and the concentration of undecomposed ammonia in the ammonia decomposition atmosphere is set at 50-100×10 -6 After annealing, a nitriding layer is formed on the surface of the oblate tube with a thickness of 1-3 μm; Step 5) performing at least two passes of wall-reducing drawing on the flat round tube with the nitrided layer to obtain a finished product; In step 4), a plurality of oblong tubes are mounted in a fixing rack, and the fixing rack is placed in an annealing furnace for batch annealing of the oblong tubes, with gaps being provided between adjacent oblong tubes; The fixing frame includes a fixed plate and a movable plate arranged in parallel, the fixed plate is provided with two sliding sleeves, the movable plate is provided with two sliding rods, the two sliding sleeves cooperate with the two sliding rods in pairs, and one end of the sliding rod extends into the sliding sleeve. The surface of the sliding sleeve is provided with a locking screw, which is used to fix the relative position between the sliding sleeve and the sliding rod. The fixed plate, movable plate, sliding rod and sliding sleeve cooperate to form a rectangular frame structure, and slots are provided on the two opposite surfaces of the fixed plate and the movable plate; It also includes a placement seat, which is provided with a placement pad. The placement pad is provided with a placement groove for placing the oblate tube, and the fixed plate and the movable plate are arranged on both sides along the length direction of the placement groove.

2. The high-precision plug-resistant TYPE-C shell drawing process according to claim 1 is characterized in that: In step 4), the temperature of the annealing furnace is set to 500°C.

3. The high-precision plug-resistant TYPE-C shell drawing process according to claim 1 is characterized in that: In step 4), the concentration of undecomposed ammonia in the ammonia decomposition atmosphere is set to 80×10 -6 .

4. The high-precision plug-resistant TYPE-C shell drawing process according to claim 1 is characterized in that: In step 4), the annealing time is 7 hours.

5. The high-precision plug-and-pull resistant TYPE-C shell drawing process according to claim 1, characterized in that: The number of the placed pads is 2, which are a fixed pad and a movable pad. The fixed pad is fixedly mounted on the base plate, and the movable pad is arranged on the base plate through a sliding track. The fixed pad is provided with a first limiting slot on the side away from the movable pad, and the movable pad is provided with a second limiting slot on the side away from the fixed pad. The fixed plate and the movable plate are respectively arranged in the first limiting slot and the second limiting slot.

6. The high-precision plug-and-pull resistant TYPE-C shell drawing process according to claim 5, characterized in that: A positioning hole is provided in the first limiting slot, and a positioning pin is provided at the bottom of the fixing plate. The positioning hole cooperates with the positioning pin to define the position of the fixing plate.

7. The high-precision plug-and-pull resistant TYPE-C shell drawing process according to claim 6, characterized in that: The tops of the fixed plate and the movable plate are provided with lifting handles.

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