Pipe cold heading forming structure
By designing a cold-forging structure for 8mm tubing, the problem of insufficient tubing performance under high pressure in diesel engines was solved, achieving improved pressure resistance and sealing performance without replacing materials, and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI USUI ENGINE PARTS
- Filing Date
- 2025-08-19
- Publication Date
- 2026-07-21
AI Technical Summary
In existing diesel engines, the oil pumps, oil rails, and injectors with ISO2974 standard interface dimensions cannot use 8 mm pipes, resulting in insufficient pipe performance under high pressure, and the cost of replacing them with high-performance materials is high.
Design an 8 mm pipe cold heading structure to meet the requirements of higher working pressure by adjusting the pipe wall thickness and cold heading process, including cold heading angle and ball transition size within a specific size range, to ensure sealing and pressure resistance.
Without changing the materials, the pressure resistance of the pipe was improved, the cost of replacing with high-performance materials was reduced, and a leak-proof sealing effect was achieved for the 8 mm pipe under high pressure.
Smart Images
Figure CN224525904U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of high-pressure fuel lines for diesel engines. Specifically, it describes the development of a new 8mm tubing structure that can be cold-formed, conforming to the ISO 2974 standard. When providing a non-standard interface for the size, a non-standard matching method is provided, which involves using an 8mm outer diameter high-pressure oil pipe, cold-forging the head, and then tightening and sealing it. Background Technology
[0002] As the operating pressure of diesel engines increases, some light and medium-duty engines have adopted the ISO 2974 standard. Oil pumps, fuel rails, and injectors with interface sizes can only be matched with fuel pipes with an outer diameter of 6 mm and an inner diameter of 3 mm. When higher working pressure is required, the limitations of the pipe material (6 mm pipe with a 3 mm inner diameter) cannot withstand the higher working pressure. Switching to higher-performance materials of the same specifications is necessary, but these higher-performance materials often come with a higher price premium. However, cold-forging structures that directly form 6 mm pipes from 8 mm outer diameter and 3 mm inner diameter pipes suffer from problems such as the inability to form the head and head cracking.
[0003] To solve the problem of 8mm pipes being unable to be molded and adapted The issue of dimensional constraints on accessories necessitates a redesign of the upsetting head structure. Once successfully developed, it will be possible to use 8mm inner diameter, 3mm tubing without altering the material, increasing wall thickness to meet higher operating pressures and reduce the costs associated with performance improvements. Utility Model Content
[0004] The purpose of this utility model is to overcome... Oil pumps, fuel rails, and injectors with interface sizes cannot use 8mm tubing. This paper proposes a novel cold-forged structure for 8mm tubing, enabling its use in various applications. The interface size is compatible with the accessories.
[0005] To achieve the above objectives, this utility model provides the following technical solution:
[0006] A cold-forged pipe structure is disclosed, comprising fuel piping with an outer diameter of 7-9 mm and other specifications close to that outer diameter, and an inner diameter of 3-4 mm. The ends of this piping are formed using a cold-forging process. The dimensions must meet the following requirements:
[0007] The forming angle A of the cold heading structure ranges from 35° to 45°.
[0008] The ball transition B dimension of the cold-forged structure ranges from 1 to 2 mm.
[0009] The height C of the front ball in the cold heading structure ranges from 3 to 4 mm.
[0010] The distance D between the front and rear spheres of the cold-forged structure ranges from 2 to 3 mm.
[0011] The diameter E of the ball after cold heading is in the range of 11–13 mm;
[0012] The transition size F of the ball diameter before cold heading is 1-2 mm.
[0013] The diameter range of the ball diameter G in the cold heading structure is 7–8 mm;
[0014] The total height H of the front end of the cold-forged structure ranges from 4 to 5 mm.
[0015] The total width I of the cold heading structure ranges from 10 to 11 mm.
[0016] Cold heading is used in low-carbon steel pipes with an outer diameter of 8.0 mm and an inner diameter of 3 to 4 mm.
[0017] Because the end structure is cold-forged, the production process is simple and can be mass-produced.
[0018] Compared with the prior art, the positive effects of this utility model are:
[0019] All dimensions of this special structure are rigorously calculated, taking into account the rigidity of the head unit structure and the feasibility of the cold heading process. It also fully considers the ultra-high pressure sealing performance after the head is assembled with the nut and connectors. In addition, the head of this application takes into account relevant correlations. The size of the ball head at the end of the head determines the angle of the nut's force-bearing surface. The size of the ball head at the front of the head and the angle of the connecting cone surface are prerequisites for sealing. The quality of the sealing performance is determined by the combined action of the nut, the head, and the cone surface.
[0020] The 8mm tubing forming small tube head of this invention has a special structure that can adapt to... The interface sizes for the oil pump, fuel rail, and injectors can simultaneously meet the leak-proof requirements under system pressures of 180MPa and below. This addresses a current market challenge where the pressure resistance of piping in light and medium-sized engines is insufficient. Furthermore, the optimized material cost of this solution offers a significant advantage over developing higher-performance material alternatives. Attached Figure Description
[0021] Figure 1 Assembly diagram Figure 1 ;
[0022] Figure 2 Assembly diagram Figure 2 ;
[0023] Figure 3 Head styles and size ranges; Detailed Implementation
[0024] The following provides a specific embodiment of the cold heading structure for pipelines according to this utility model.
[0025] Example 1
[0026] Please see the appendix Figure 1 and Figure 2 The sealing structure of this high-pressure oil pipe, comprising the oil pipe connected to mating parts (such as injectors, oil pumps, oil rails, etc.) via a connecting nut, is characterized in that, through the engagement of the threads, the conical surface of the rear end of the nut contacts the rear ball of the head at points A and B, forming a compression. The front ball of the head contacts the conical surface of the mating part at points C and D, also forming a compression. Since the front and rear balls are coaxial, the compression applied to the rear ball by the nut is converted into compression of the front ball on the mating parts, causing the front ball to deform and form a sealing structure with the mating parts. This includes, but is not limited to, external thread sealing or internal thread sealing. (See attached...) Figure 1 The two application formats are shown.
[0027] Appendix Figure 3 This describes the dimensions and design of the cold-forged structure for the high-pressure oil pipe. The prototype of this head design has been completed and its performance verified. The core component lies in the front ball of the head. Size to meet The interface dimensions are required to be designed to be between 7 mm and 8 mm. The head taper (A°) must be controlled between 30° and 45° to ensure reliable head molding. This has been verified to reduce the depth of internal surface cracks and the difficulty of head molding. (The last part, "head rear ball," appears to be unrelated and likely refers to a different design element.) To ensure sufficient contact surface and absorption of axial force when in contact with the tapered surface of the nut, the size is controlled between 11 mm and 13 mm.
[0028] Figure 3 Head size range
[0029] 35～45 1～2 3～4 2～3 11～13 1～2 7～8 4～5 10～11
[0030] The positive effect of this utility model is that it can be applied to the 60° inner cone interface standard of ISO2974-diesel engines-high-pressure fuel injection components, and when selected... When it comes to the size of the interface, the standard recommends a 6mm outer diameter pipe, but an 8mm outer diameter pipe can be used with this cold-forged structure. With the increasing operating pressure of internal combustion engines, the requirements for the pressure resistance and mechanical properties of the pipe material are also increasing. To meet these higher usage needs, continuing to use a 6mm outer diameter pipe would require developing higher-performance materials, which involves a long development cycle and high investment. However, the successful development of this new type of connector allows for the use of 8mm outer diameter pipes without changing the material properties. Regarding the size of the interface fittings, the 8mm outer diameter tube has a thicker wall than the 6mm outer diameter tube, resulting in superior performance in all aspects. This performance improvement doesn't require material changes, eliminating the time and high costs associated with material development and verification. The head is cold-stamped in one piece, with a front ball... It features a small ball diameter and a tapered A-shaped transition. Its unique characteristic lies in using 8mm outer diameter tubing to form the small-diameter ball sealing structure, which can withstand high pressure.
[0031] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the concept of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.
Claims
1. A cold-forging structure for pipelines, characterized in that: The total height H of the front end of the cold-forged structure ranges from 4 to 5 mm. The total width I of the cold heading structure ranges from 10 to 11 mm.
2. The cold heading structure for pipelines as described in claim 1, characterized in that: The forming angle A of the cold heading structure ranges from 35° to 45°.
3. The cold heading structure for pipelines as described in claim 1, characterized in that: The size range of the ball transition B after cold heading is 1-2 mm.
4. The cold heading structure for pipelines as described in claim 1, characterized in that: The height C of the front ball in the cold heading structure ranges from 3 to 4 mm.
5. The cold heading structure for pipelines as described in claim 1, characterized in that: The distance D between the front and rear centers of the cold-forged structure is 2-3 mm.
6. The cold heading structure for pipelines as described in claim 1, characterized in that: The diameter E of the ball after cold heading is in the range of 11 to 13 mm.
7. The cold heading structure for pipelines as described in claim 1, characterized in that: The transition size F of the ball diameter before cold heading is in the range of 1 to 2 mm.
8. The cold heading structure for pipelines as described in claim 1, characterized in that: The diameter G of the front ball in the cold heading structure ranges from 7 to 8 mm.