A stainless steel fuel high pressure oil pipe and its manufacturing process

Abstract

The present invention provides a stainless steel fuel high-pressure oil pipe, comprising a body and two joints, characterized in that: the two ends of the body are respectively a first end and a second end, the two joints are respectively a first joint and a second joint, the first end of the body is integrally formed with the first joint, and the second end of the body is integrally formed with the second joint. The present invention solves the first problem existing in the prior art: how to make the stainless steel fuel high-pressure oil pipe and the corresponding joints with different hardness at the two ends have no gaps and no leakage.

Description

Technical Field

[0001] The invention relates to the technical field of a fuel high-pressure oil pipe connecting a high-pressure oil pump and a high-pressure oil rail in a cylinder direct injection engine, and in particular to a stainless steel fuel high-pressure oil pipe and a manufacturing process thereof. Background Art

[0002] First of all, the stainless steel high-pressure fuel pipe needs to be connected to the corresponding joint during use with no gap between the two to avoid oil leakage. Therefore, how to make the stainless steel high-pressure fuel pipe and the corresponding joint connected without gap becomes a problem that needs to be solved.

[0003] In addition, there are two existing manufacturing processes for high-pressure fuel oil pipes. One is to perform high-temperature brazing on the high-pressure fuel pipe composed of the fuel pipe, machined sealing joint, copper ring and nut as a whole, so that the hardness of the sealing joints at both ends of the high-pressure fuel pipe is soft. The reliability of the matching seal of the soft sealing joint and the soft pipe joint will be reduced; at the same time, the nut is subjected to high-temperature annealing in this process, and the nut also becomes soft, and the locking performance of the nut is greatly reduced, which greatly reduces the reliability of the fuel pipe seal; the other is to cold form the sealing joints at both ends of the high-pressure fuel pipe. Due to the cold working hardening effect, the hardness of the sealing joint is greatly improved, and it cannot effectively perform sealing matching and yielding with the hard counterpart pipe joint, reducing the reliability of the seal. Both methods have great risks for pipeline sealing.

[0004] Therefore, how to use the same high-pressure fuel oil pipe to meet the sealing requirements of both the soft counterpart pipe joint and the hard counterpart pipe joint has become an urgent problem to be solved. In addition, how to avoid the high-temperature annealing of the nut during this process, which will greatly reduce the locking performance of the nut and the reliability of the oil pipe seal, also needs to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide a stainless steel high-pressure fuel pipe and a manufacturing process thereof, mainly to solve the problem one existing in the above-mentioned prior art: how to make the stainless steel high-pressure fuel pipe and the corresponding joint seamlessly connected; problem two: how to use the same high-pressure fuel pipe to meet the sealing requirements of matching with soft counterpart pipe joints and also meet the sealing requirements of matching with hard counterpart pipe joints; problem three: how to avoid the nut being subjected to high-temperature annealing in this process, avoiding a significant decrease in the locking performance of the nut, and greatly reducing the reliability of the pipe seal, and provide a stainless steel high-pressure fuel pipe and a manufacturing process thereof.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a stainless steel fuel high-pressure oil pipe, including a main body and two joints, characterized in that: the two ends of the main body are respectively a first end and a second end, the two joints are respectively a first joint and a second joint, the first end of the main body is integrally formed with the first joint, and the second end of the main body is integrally formed with the second joint.

[0007] Further, the interior of the first joint and / or the interior of the second joint is a hollow part in a cylindrical shape, and the exterior of the first joint and / or the exterior of the second joint is a spherical or double spherical structure;

[0008] Or the interior of the first joint and / or the interior of the second joint is a hollow portion formed by a spherical surface or a double spherical surface, and the exterior of the first joint and / or the exterior of the second joint is a spherical surface or a double spherical surface structure.

[0009] Furthermore, the body is bent into at least three bending parts.

[0010] Furthermore, the bending angle range of at least one bending portion close to the middle part of the main body is 90°-170°; the first joint and the second joint have different hardness; and two back-to-back nuts are sleeved on the main body.

[0011] Furthermore, the first end and the first joint at one end of the body are soft sealing joints formed by cold forming and then high temperature annealing; the second end and the second joint at the other end of the body are hard sealing joints formed by cold forming.

[0012] Furthermore, the hardness value of the soft sealing joint of the stainless steel high-pressure fuel pipe is between 110-230HV1; the hardness value of the hard sealing joint of the stainless steel high-pressure fuel pipe is between 240-440HV1.

[0013] Furthermore, the stainless steel high-pressure fuel pipe is also sleeved with at least two nuts, which are located between the soft sealing joint and the hard sealing joint on the stainless steel high-pressure fuel pipe; the nuts have not been subjected to high-temperature annealing treatment.

[0014] A manufacturing process of a stainless steel high-pressure fuel pipe, which relates to the above-mentioned stainless steel high-pressure fuel pipe, is characterized in that it comprises the following steps:

[0015] Step S1: Cutting the stainless steel straight tube;

[0016] Step S2: turning the outer diameters of both ends;

[0017] Step S3: chamfering both ends;

[0018] Step S4: first cleaning;

[0019] Step S5: cold forming a port at one end of the stainless steel straight tube;

[0020] Step S6: first polishing;

[0021] Step S7: Second cleaning

[0022] Step S8: high temperature annealing;

[0023] Step S9: first marking;

[0024] Step S10: Put two nuts on;

[0025] Step S11: cold forming a port at the other end of the stainless steel straight tube;

[0026] Step S12: second polishing;

[0027] Step S13: third cleaning;

[0028] Step S14: marking for the second time;

[0029] Step S15: Sealing joint size detection;

[0030] Step S16: bending the pipe;

[0031] Step S17: Sealing joint position and pipe type detection;

[0032] Step S18: Appearance inspection;

[0033] Step S19: Packing and storage.

[0034] Further, the step S2 specifically includes the following steps:

[0035] Step S2-1: providing a turning device;

[0036] Step S2-2: Put the cut stainless steel straight tube into a turning device, and use the turning device to precisely turn the outer diameters of both ends of the stainless steel straight tube. The length of the outer diameter is 2-20 mm, and the surface accuracy of the outer diameter is Rz0.8-10.

[0037] Further, the step S3 specifically includes the following steps:

[0038] Step S3-1: providing a processing device for chamfering the ends of a stainless steel straight tube;

[0039] Step S3-2: Place the stainless steel straight tube after turning into a chamfering processing device, and chamfer the inner and outer diameters of the tube ends of the stainless steel straight tube by the chamfering processing device. The outer diameter of the tube end is rounded or chamfered, and the inner diameter of the tube end is chamfered.

[0040] Further, the step S5 specifically includes the following steps:

[0041] Step S5-1: providing a cold forming device for cold forming a stainless steel straight pipe end;

[0042] Step S5-2: cold forming the port at one end of the stainless steel straight tube through a cold forming device.

[0043] Further, the step S6 specifically includes the following steps:

[0044] Step S6-1: The stainless steel straight tube sealing joint that has been cold-formed at one end (actually the sealing joint at one end of the corresponding soft joint that has not been annealed at high temperature) is polished for the first time by using a grinding wheel to improve the surface accuracy to Rz0.8-10, or by using mechanical spinning polishing to improve the surface accuracy to Rz0.8-10.

[0045] Further, the step S8 specifically includes the following steps:

[0046] Step S8-1: providing a high temperature annealing device;

[0047] Step S8-2: high temperature annealing the stainless steel straight tube which has been cold-formed and polished at one end.

[0048] A stainless steel high-pressure fuel pipe, characterized in that a sealing joint at one end of the stainless steel high-pressure fuel pipe is a soft sealing joint that is cold-formed and then annealed at high temperature, and a sealing joint at the other end of the stainless steel high-pressure fuel pipe is a hard sealing joint that is cold-formed.

[0049] A manufacturing process of a stainless steel high-pressure fuel pipe, which relates to the above-mentioned stainless steel high-pressure fuel pipe, is characterized in that it comprises the following steps:

[0050] Step S1: After the raw stainless steel straight tube is cut, a port at one end of the stainless steel straight tube is subjected to a first cold forming process;

[0051] Step S2: high temperature annealing is performed on the end of the stainless steel straight tube that has undergone the first cold forming process to form a soft sealing joint;

[0052] Step S3: inserting two back-to-back nuts through the unprocessed other end port of the stainless steel straight tube;

[0053] Step S4: cold forming the unprocessed other end of the stainless steel straight pipe to form a hard seal joint;

[0054] Step S5: bending the stainless steel straight pipe with both ends of the pipe processed to form a stainless steel fuel high-pressure pipe with a soft sealing joint at one end and a hard sealing joint at the other end.

[0055] In view of the above technical features, the present invention has the following beneficial effects:

[0056] 1. In the stainless steel high-pressure fuel pipe of the present invention, the first end and the first joint are integrally formed to form a sealed connection, and the second end and the second joint are integrally formed to form a sealed connection, so that the stainless steel high-pressure fuel pipe is seamlessly connected to the corresponding joint and will not leak oil.

[0057] 2. In the stainless steel high-pressure fuel pipe of the present invention, the first joint has a cylindrical hollow portion inside and a spherical or double-spherical structure outside; this design enhances the strength of the first joint. That is, the problem of how to improve the strength of the first joint is solved here.

[0058] 3. The main body of a stainless steel high-pressure fuel oil pipe of the present invention is bent into at least three bends. The bending angle range of at least one bend near the middle of the main body is 90°-170°; this design makes the main body of a stainless steel high-pressure fuel oil pipe more tensilely flexible, reduces the rigidity of the main body, ensures the axial force of the nut, and further ensures the sealing reliability of the sealing structure formed by the nut between the main body and the counterpart.

[0059] 4. A stainless steel high-pressure fuel pipe of the present invention has a first joint and a second joint with different hardnesses. When the same high-pressure fuel pipe is used, it can meet the sealing requirements of matching with soft counterpart pipe joints and also meet the sealing requirements of matching with hard counterpart pipe joints.

[0060] 5. The present invention provides a stainless steel fuel high-pressure oil pipe with a soft sealing joint at one end and a hard sealing joint at the other end. The soft sealing joint can match a harder counterpart pipe joint, while the hard sealing joint can match a softer counterpart pipe joint. At the same time, the nut is not annealed to maintain good tightening and sealing reliability, which is very consistent with the actual hardness and softness of the counterpart pipe joint of the fuel high-pressure oil pipe. The reliability of the seal is improved through the soft and hard matching.

[0061] 6. The stainless steel high-pressure fuel pipe and its manufacturing process in the present invention economically and reliably performs high-temperature annealing on one end of the stainless steel high-pressure fuel pipe, avoiding the annealing of the nut and the cold-formed sealing joint at the other end, so that the stainless steel high-pressure fuel pipe can be adapted to the reliable assembly of the handpiece pipe joints with different hardness.

[0062] 7. The manufacturing process of a stainless steel high-pressure fuel oil pipe in the present invention eliminates surface defects such as tearing, indentation, and bumping by turning the outer surfaces of both ends of the straight pipe, thereby improving the surface roughness; reduces the surface hardness of the sealing joint by high-temperature annealing at one end, thereby improving the sealing reliability with the hard counterpart pipe joint; maintains the original locking and sealing function of the nut by avoiding high-temperature annealing of the nut; and maintains a relatively high hardness by cold forming the sealing joint at the other end, thereby enabling reliable sealing with the soft counterpart pipe joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a structural schematic diagram of a stainless steel high-pressure fuel pipe in Example 1.

[0064] Figure 2 It is a structural schematic diagram of a stainless steel high-pressure fuel pipe in Example 2.

[0065] Figure 3 It is a structural schematic diagram of a stainless steel high-pressure fuel pipe in Example 3.

[0066] Figure 4 This is a manufacturing process flow chart of a stainless steel high-pressure fuel pipe in Example 4.

[0067] In the figure: 1 is the main body of the stainless steel fuel high-pressure oil pipe; 1-1 is the first end; 1-2 is the second end; 2 is the soft sealing joint; 3 is the hard sealing joint; 4 is the bending part; 5 is the nut; 8 is the first joint; 9 is the second joint. DETAILED DESCRIPTION

[0068] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0069] See also Figure 1 , Specific embodiment 1, this embodiment 1 provides a stainless steel fuel high-pressure oil pipe, including a main body 1 and two joints, characterized in that: the two ends of the main body 1 are respectively a first end 1-1 and a second end 1-2, the two joints are respectively a first joint 8 and a second joint 9, the first end 1-1 of the main body 1 is integrally formed with the first joint 8, and the second end 1-2 of the main body 1 is integrally formed with the second joint 9.

[0070] The interior of the first joint 8 and / or the interior of the second joint 9 is a hollow part in the shape of a cylinder, and the exterior of the first joint 8 and / or the exterior of the second joint 9 is a spherical or double-spherical structure; or the interior of the first joint 8 and / or the interior of the second joint 9 is a hollow part formed by a spherical or double-spherical surface, and the exterior of the first joint 8 and / or the exterior of the second joint 9 is a spherical or double-spherical structure.

[0071] In the present embodiment 1, it is preferred that the outside of the first joint 8 and the outside of the second joint 9 are spherical, and the inside of the first joint 8 and the inside of the second joint 9 are hollow parts formed by spherical surfaces. This design has a large spherical surface area, is easy to process and measure, and has good quality reliability.

[0072] As an alternative, the shape of the soft sealing joint 2 and / or the hard sealing joint 3 of the stainless steel fuel high-pressure oil pipe is spherical, conical, double spherical or cylindrical. The sealing joint shapes of the soft sealing joint 2 and / or the hard sealing joint 3 include but are not limited to spherical, conical, double spherical and cylindrical shapes, and their respective geometric combinations.

[0073] The body 1 is bent into at least three bending portions 4. The bending angle of at least one bending portion 4 near the middle of the body 1 is in the range of 90°-170°; the bending radius of the bending portion 4 is greater than 5 mm, meeting the actual assembly requirements.

[0074] The first joint 8 and the second joint 9 have different hardnesses, and the soft sealing joint 2 is formed by the first joint 8, and the hard sealing joint 3 is formed by the second joint 9; in this way, the stainless steel fuel high-pressure oil pipe body 11 can adapt to the reliable assembly of the hand pipe joints with different hardnesses.

[0075] The body 1 is sleeved with two back-to-back nuts 5. The nuts 5 are located between the soft seal joint 2 and the hard seal joint 3 on the stainless steel fuel high-pressure oil pipe;

[0076] See also Figure 2 , Specific embodiment 2, this embodiment 2 provides a stainless steel fuel high-pressure oil pipe, the difference between embodiment 2 and embodiment 1 is that the outside of the first joint 8 and the outside of the second joint 9 are spherical, and the inside of the first joint 8 and the inside of the second joint 9 are cylindrical hollow parts. In this way, the outer spherical surface area of ​​the two joints is large, easy to process and measure, and has good quality reliability. At the same time, the hollow parts of the two joints are cylindrical, which can increase the strength of the two joints.

[0077] See also Figure 3, specific embodiment 3, this embodiment 3 provides a stainless steel fuel high-pressure oil pipe, the difference between embodiment 2 and the previous embodiment is that the interior of the first joint 8 and / or the interior of the second joint 9 is a hollow part formed by a double spherical surface, and the outside of the first joint 8 and / or the outside of the second joint 9 is a double spherical structure.

[0078] See also Figure 4 , Specific embodiment 4, this embodiment 4 provides a manufacturing process of a stainless steel high-pressure fuel pipe, which relates to a stainless steel high-pressure fuel pipe as described in any one of embodiments 1 to 3 above, characterized in that it includes the following steps:

[0079] Step S1: Cutting the stainless steel straight tube; the step S1 specifically comprises the following steps:

[0080] Step S1-1: providing a machining device and a chip removal tooling device;

[0081] Step S1-2: machining and cutting the raw stainless steel straight tube and removing chips through machining equipment and chip removal tooling equipment; the raw stainless steel straight tube, that is, the incoming straight tube without modification, is generally long in length and needs to be cut, that is, the raw stainless steel straight tube is cut according to the required length of the product. At this time, the machining equipment cuts the material and uses the chip removal tooling for chip removal at the same time, in order to avoid the metal chips generated during the cutting process of the raw stainless steel straight tube from scratching the outer surface of the straight tube and affecting the processing effect of the subsequent processing steps.

[0082] Step S2: turning the outer diameters of both ends; the step S2 specifically includes the following steps:

[0083] Step S2-1: providing a turning device;

[0084] Step S2-2: Place the cut stainless steel straight tube into a turning device, and use the turning device to precisely turn the outer diameters of both ends of the stainless steel straight tube. The length of the outer diameter is 2-20 mm, and the surface accuracy of the outer diameter is Rz0.8-10. Turning the outer diameters at both ends is to improve the surface accuracy of the outer diameters at both ends.

[0085] Step S3: chamfering both ends; the step S3 specifically includes the following steps:

[0086] Step S3-1: providing a processing device for chamfering the ends of a stainless steel straight tube;

[0087] Step S3-2: Place the stainless steel straight tube after turning into a chamfering processing device, and chamfer the inner and outer diameters of the tube ends of the stainless steel straight tube by the chamfering processing device. The outer diameter of the tube ends is rounded or chamfered, and the inner diameter of the tube ends is chamfered; for example, the outer diameter is rounded R0.1-R5 or chamfered C0.1-C5, and the inner diameter is chamfered C0.1-C5. Prepare for the subsequent cold forming of the two ends of the stainless steel straight tube.

[0088] Step S4: first cleaning; Step S4 specifically includes the following steps:

[0089] Step S4-1: The chamfered stainless steel straight tube is subjected to a first cleaning to remove oil and dust. The first cleaning includes cleaning the entire inside and outside of the stainless steel straight tube, especially cleaning the inner diameter and outer diameter of the tube openings at both ends of the stainless steel straight tube to remove oil and dust, mainly in preparation for subsequent cold forming and the first polishing.

[0090] Step S5: cold forming a port at one end of the stainless steel straight tube; the step S5 specifically comprises the following steps:

[0091] Step S5-1: Provide a cold forming device for cold forming the end of a stainless steel straight tube; at this time, the end of the stainless steel straight tube can also be rotated and clamped using a tooling, and the mold is used to perform cold forming processing on the end of the stainless steel straight tube.

[0092] Step S5-2: cold forming the port at one end of the stainless steel straight tube through a cold forming device; that is, the port at the end of the stainless steel straight tube is placed in the cold forming device, clamped by a tooling, and cold formed by a mold at the same time, which is also called the first cold forming of one end of the stainless steel straight tube. The cold formed port of the stainless steel straight tube is prepared for subsequent high temperature annealing. Depending on the size and shape of the sealing joint, the forming process step is 1 step or within 5 steps.

[0093] Step S6: first polishing; Step S6 specifically includes the following steps:

[0094] Step S6-1: The stainless steel straight pipe sealing joint that has been cold-formed at one end (actually the sealing joint at one end of the corresponding soft joint that has not been annealed at high temperature) is first polished by grinding wheel polishing to improve the surface accuracy to Rz0.8-10, or by mechanical spinning polishing to improve the surface accuracy to Rz0.8-10. Depending on the size and shape of the sealing joint, the grinding wheel polishing and mechanical spinning polishing steps are 1 step or within 5 steps.

[0095] Step S7: Second cleaning Step S7 specifically includes the following steps:

[0096] Step S7-1: The stainless steel straight tube after the first polishing is subjected to a second cleaning to remove oil and dust. The second cleaning includes cleaning the entire inside and outside of the stainless steel straight tube, especially cleaning the inner diameter and outer diameter of the tube openings at both ends of the stainless steel straight tube to remove oil and dust, mainly in preparation for subsequent high-temperature annealing.

[0097] Step S8: high temperature annealing; the step S8 specifically includes the following steps:

[0098] Step S8-1: providing a high temperature annealing device;

[0099] Step S8-2: The stainless steel straight tube that has been cold-formed and polished at one end is subjected to overall high-temperature annealing; during high-temperature annealing, air, reducing gas, hydrogen, nitrogen or ammonia decomposition gas can be used for high-temperature annealing, and a mesh belt tunnel furnace or induction equipment can be used for annealing, and the workpiece annealing temperature is 950-1190 degrees Celsius, and the time is 1-10 minutes. The temperature of each heating zone of the tunnel furnace muffle is set between 800-1300 degrees Celsius, the mesh belt speed is 100-500 mm per minute, and the atmosphere dew point when using reducing gas, hydrogen, nitrogen or ammonia decomposition gas is controlled below minus five degrees Celsius.

[0100] Step S9: marking for the first time; the step S9 specifically includes the following steps:

[0101] Step S9-1: marking the stainless steel straight pipe after high temperature annealing for the first time, i.e., marking to prevent mistakes. Marking is made on the pipe body near the end of the stainless steel straight pipe, such as dotting, to indicate that this part has been subjected to high temperature annealing.

[0102] Step S10: Put two nuts 5 on; the step S10 specifically includes the following steps:

[0103] Step S10-1: Select two nuts 5 and insert them back to back from the other unformed end of the stainless steel straight tube to complete the socketing of the nuts 5 and the stainless steel straight tube. The two nuts are sleeved on the stainless steel straight tube back to back, which is efficient and the matching direction of the nuts and the two ends of the stainless steel straight tube is correct. At this time, the two nuts 5 are sleeved on the stainless steel straight tube. Since the stainless steel straight tube has completed the cold forming and high temperature annealing operations, the high temperature annealing operation of the nuts 5 can be completely avoided, that is, the two nuts 5 are not subjected to high temperature annealing together with the stainless steel straight tube, and the hardness of the nuts 5 will not be affected, so that the nuts 5 can maintain the original good hardness, and the nuts 5 have a better fastening effect on the workpiece (i.e., the two ends of the stainless steel straight tube), that is, the fastening and fixing effect between the two ends of the stainless steel fuel high-pressure oil pipe and its corresponding counterpart is better.

[0104] Step S11: cold forming a port at the other end of the stainless steel straight tube; the step S11 specifically includes the following steps:

[0105] Step S11-1: Place the other end of the stainless steel straight pipe into a cold forming device, clamp it with a tooling, and use a mold to cold form the other end of the stainless steel straight pipe to form a hard seal joint 3. The other end of the stainless steel straight pipe at this time refers to the end that has not been annealed at high temperature, which is actually the end of the stainless steel straight pipe that has not been processed, and is also the end of the stainless steel straight pipe where the two nuts 5 are inserted. The forming process step is 1 step or within 5 steps.

[0106] Step S12: second polishing; the step S12 specifically includes the following steps:

[0107] Step S112-1: The hard seal joint 3 at the other end of the stainless steel straight pipe is polished for the second time, using a grinding wheel to improve the surface accuracy to Rz0.8-10, or using mechanical spinning polishing to improve the surface accuracy to Rz0.8-10. At this time, the stainless steel straight pipe is processed into a stainless steel fuel high-pressure oil pipe. The stainless steel fuel high-pressure oil pipe formed at this time has a soft seal joint 2 that has been cold-formed and high-temperature annealed at one end, and a hard seal joint 3 that has only been cold-formed at the other end. The hard seal joint 3 does not have a high-temperature annealing process.

[0108] Step S13: third cleaning; the step S13 specifically comprises the following steps:

[0109] Step S13-1: The stainless steel straight pipe whose other end has been cold-formed to form a hard-sealed joint 3 (i.e., the stainless steel fuel high-pressure oil pipe that has completed the hard-sealed joint 3 processing) is cleaned for the third time, including cleaning the entire inside and outside of the stainless steel straight pipe to remove oil and dust to ensure the cleanliness of the product, especially the inside of the pipe.

[0110] Step S14: marking for the second time; the step S14 specifically includes the following steps:

[0111] Step S14-1: Perform a second marking on the nut 5 or the stainless steel straight tube (i.e., stainless steel fuel high-pressure oil pipe) for product traceability. For example, a QR code or a plain code laser engraving mark can be performed on the nut 5 or the stainless steel straight tube, giving each stainless steel straight tube or stainless steel fuel high-pressure oil pipe an independent ID code for product traceability.

[0112] Step S15: Sealing joint size detection; Step S15 specifically includes the following steps:

[0113] Step S15-1: 100% geometric dimension and form tolerance inspection is performed on the soft seal joint 2 and the hard seal joint 3 at both ends of the stainless steel fuel high-pressure oil pipe. For example, the specific inspection items include: the ball diameter and tolerance of the sealing surface of the soft seal joint 2 and / or the hard seal joint 3, the contour of the sealing surface, the ball diameter and tolerance of the pressing surface, etc.

[0114] Step S16: bending the pipe; the step S16 specifically includes the following steps:

[0115] Step S16-1: bend the stainless steel high-pressure fuel pipe to form at least one bending portion 4, wherein the bending radius of the bending portion 4 is greater than 5 mm. The bending portion 4 is formed to meet the needs of practical applications, such as product installation requirements.

[0116] Step S17: Sealing joint position and pipe type detection; Step S17 specifically includes the following steps:

[0117] Step S17-1: After the stainless steel high-pressure fuel pipe is bent, the position of the soft seal joint 2 and the hard seal joint 3 and the shape of the stainless steel high-pressure fuel pipe are inspected by using mechanical inspection equipment or optical imaging inspection equipment. For example, the purpose of this inspection is not to determine whether the stainless steel high-pressure fuel pipe meets the acceptance requirements after processing.

[0118] Step S18: Appearance inspection; Step S18 specifically includes the following steps:

[0119] Step S18-1: Use a magnifying glass device to perform an appearance inspection on the stainless steel fuel high-pressure oil pipe to remove defective parts such as defects. For example, the appearance inspection standard may be no defects, no wire drawing, no embossing, no pits, no indentations, and no bumps.

[0120] Step S19: Packing and storage.

[0121] The nut 5 has not been subjected to high temperature annealing. The two nuts 5 are inserted into the oil pipe after one end of the stainless steel straight pipe has been subjected to high temperature annealing and before the other end has been cold formed, so that the nut 5 is kept in its initial state without being subjected to high temperature annealing, thereby ensuring good tightening and sealing reliability.

[0122] The hardness value of the soft seal joint 2 of the stainless steel fuel high pressure oil pipe is between 110-230HV1, including 110HV1 and 230HV1; the hardness value of the hard seal joint 3 of the stainless steel fuel high pressure oil pipe is between 240-440HV1, including 240HV1 and 440HV1. The selection of the hardness value of the soft seal joint 2 and the hardness value of the hard seal joint 3 can correspond to different austenitic, martensitic, and duplex stainless steels.

[0123] The sealing joint at one end of the stainless steel fuel high pressure oil pipe is a soft sealing joint 2 that is cold formed and then annealed at high temperature, and the sealing joint at the other end of the stainless steel fuel high pressure oil pipe is a hard sealing joint 3 that is cold formed. At this time, the sealing joint at one end of the stainless steel fuel high pressure oil pipe is only composed of a stainless steel pipe, and is first formed into a sealing joint shape by cold forming, and then annealed at high temperature to eliminate the cold work hardening effect and reduce the hardness value of the soft sealing joint 2. The hard sealing joint 3 at the other end of the stainless steel fuel high pressure oil pipe is only composed of a stainless steel pipe, and is first formed into a sealing joint shape by cold forming, and is hardened by cold work to increase the hardness value of the hard sealing joint 3. In fact, the sealing joint at one end of the high pressure oil pipe is cold formed and then annealed at high temperature, while the other end is only cold formed without high temperature annealing. In addition, the stainless steel materials used in the stainless steel fuel high pressure oil pipe include all austenite, martensite, ferrite and duplex stainless steels. The raw materials of the stainless steel fuel high pressure oil pipe are preferably cold rolled or cold drawn stainless steel seamless steel pipes. The outer diameter of the stainless steel pipe of the stainless steel fuel high pressure oil pipe is between 4-20 mm, and the wall thickness is between 0.5-6 mm.

[0124] Specific embodiment 5, a stainless steel high-pressure fuel pipe provided in this embodiment 5 is the same as the stainless steel high-pressure fuel pipe in specific embodiment 1, except that the manufacturing process steps of the stainless steel high-pressure fuel pipe in this embodiment 5 are simpler, and include the following steps:

[0125] Step S1: After the raw stainless steel straight tube is cut, a port at one end of the stainless steel straight tube is subjected to a first cold forming process;

[0126] Step S2: high temperature annealing is performed on the end of the stainless steel straight pipe that has undergone the first cold forming process to form a soft sealing joint 2;

[0127] Step S3: inserting two nuts 5 back to back through the unprocessed other end of the stainless steel straight tube;

[0128] Step S4: cold forming the unprocessed other end of the stainless steel straight pipe to form a hard sealing joint 3;

[0129] Step S5: bending the stainless steel straight pipe with both ends of the pipe processed to form a stainless steel fuel high-pressure pipe with a soft sealing joint 2 at one end and a hard sealing joint 3 at the other end.

[0130] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A manufacturing process for a stainless steel high-pressure fuel pipe, characterized in that: The stainless steel high-pressure fuel pipe comprises a body and two joints, wherein the two ends of the body are respectively a first end and a second end, and the two joints are respectively a first joint and a second joint, wherein the first end of the body is integrally formed with the first joint, and the second end of the body is integrally formed with the second joint; the first end of one end of the body and the first joint are soft-sealed joints formed by first cold forming and then high-temperature annealing; the second end and the second joint at the other end of the body are hard-sealed joints formed by cold forming; the hardness value of the soft-sealed joint of the stainless steel high-pressure fuel pipe is between 110 and 230 HV1; the hardness value of the hard-sealed joint of the stainless steel high-pressure fuel pipe is between 240 and 440 HV1; the stainless steel high-pressure fuel pipe is also sleeved with at least two nuts, which are located between the soft-sealed joint and the hard-sealed joint on the stainless steel high-pressure fuel pipe; the nut has not been subjected to high-temperature annealing treatment, and comprises the following steps: Step S1: Cutting the stainless steel straight tube; Step S2: turning the outer diameters of both ends; Step S3: chamfering both ends; Step S4: first cleaning; Step S5: cold forming a port at one end of the stainless steel straight tube; Step S6: first polishing; Step S7: Second cleaning Step S8: high temperature annealing; Step S9: first marking; Step S10: Put two nuts on; Step S11: cold forming a port at the other end of the stainless steel straight tube; Step S12: second polishing; Step S13: third cleaning; Step S14: marking for the second time; Step S15: Sealing joint size detection; Step S16: bending the pipe; Step S17: Sealing joint position and pipe type detection; Step S18: Appearance inspection; Step S19: Packing and storage.

2. The manufacturing process of a stainless steel high-pressure fuel pipe according to claim 1, characterized in that: The interior of the first joint and / or the interior of the second joint is a hollow part in a cylindrical shape, and the exterior of the first joint and / or the exterior of the second joint is a spherical or double spherical structure; Or the interior of the first joint and / or the interior of the second joint is a hollow portion formed by a spherical surface or a double spherical surface, and the exterior of the first joint and / or the exterior of the second joint is a spherical surface or a double spherical surface structure.

3. The manufacturing process of a stainless steel high-pressure fuel pipe according to claim 2 is characterized in that: The body is bent into at least three bending parts.

4. The manufacturing process of a stainless steel high-pressure fuel pipe according to claim 3 is characterized in that: The bending angle range of at least one bending portion near the middle part of the main body is 90°-170°; the first joint and the second joint have different hardness; and two back-to-back nuts are sleeved on the main body.

5. A manufacturing process for a stainless steel high-pressure fuel pipe according to claim 1, 2, 3 or 4, characterized in that: The step S2 specifically includes the following steps: Step S2-1: providing a turning device; Step S2-2: Put the cut stainless steel straight tube into a turning device, and use the turning device to precisely turn the outer diameters of both ends of the stainless steel straight tube. The length of the outer diameter is 2-20 mm, and the surface accuracy of the outer diameter is Rz0.8-10.

6. The manufacturing process of a stainless steel high-pressure fuel pipe according to claim 5, characterized in that: The step S3 specifically comprises the following steps: Step S3-1: providing a processing device for chamfering the ends of a stainless steel straight tube; Step S3-2: Place the stainless steel straight tube after turning into a chamfering processing device, and chamfer the inner and outer diameters of the tube ends of the stainless steel straight tube by the chamfering processing device. The outer diameter of the tube end is rounded or chamfered, and the inner diameter of the tube end is chamfered.

7. A manufacturing process for a stainless steel high-pressure fuel pipe according to claim 6, characterized in that: The step S5 specifically comprises the following steps: Step S5-1: providing a cold forming device for cold forming a stainless steel straight pipe end; Step S5-2: cold forming the port at one end of the stainless steel straight tube through a cold forming device.

8. The manufacturing process of a stainless steel high-pressure fuel pipe according to claim 7, characterized in that: The step S6 specifically comprises the following steps: Step S6-1: The stainless steel straight pipe sealing joint that has been cold-formed at one end is polished for the first time, using a grinding wheel to polish and improve the surface accuracy to Rz0.8-10, or using mechanical spinning polishing to improve the surface accuracy to Rz0.8-10.

9. A manufacturing process for a stainless steel high-pressure fuel pipe according to claim 8, characterized in that: The step S8 specifically includes the following steps: Step S8-1: providing a high temperature annealing device; Step S8-2: High temperature annealing is performed on the stainless steel straight tube which has been cold formed and polished at one end.

10. A manufacturing process for a stainless steel high-pressure fuel pipe, characterized in that: The sealing joint at one end of the stainless steel high-pressure fuel pipe is a soft sealing joint that is annealed at high temperature after cold forming, and the sealing joint at the other end of the stainless steel high-pressure fuel pipe is a hard sealing joint that is cold formed, which includes the following steps: Step S1: After the raw stainless steel straight tube is cut, a port at one end of the stainless steel straight tube is subjected to a first cold forming process; Step S2: high temperature annealing is performed on the end of the stainless steel straight tube that has undergone the first cold forming process to form a soft sealing joint; Step S3: inserting two back-to-back nuts through the unprocessed other end port of the stainless steel straight tube; Step S4: cold forming the unprocessed other end of the stainless steel straight pipe to form a hard seal joint; Step S5: bending the stainless steel straight pipe with both ends of the pipe processed to form a stainless steel fuel high-pressure pipe with a soft sealing joint at one end and a hard sealing joint at the other end.

Images