JP7401047B2 - Manufacturing method for fuel introduction inlet - Google Patents

Description

The present invention relates to a method of manufacturing a fuel introduction inlet attached to a delivery pipe used in an internal combustion engine.

Conventionally, in internal combustion engines, a delivery pipe has been used that distributes fuel supplied from a fuel supply pipe to fuel injection valves provided in each cylinder.

Conventionally, this type of delivery pipe has a cylindrical body, and a plurality of insertion parts for attaching fuel injection valves are provided at predetermined intervals in the longitudinal direction of the cylindrical body having a fuel passage. The insertion portions are each provided with an insertion port that communicates with the fuel passage of the delivery pipe, and a rear end of a fuel injection valve (not shown) is inserted into the insertion port. One end of the delivery pipe is integrally provided with a fuel inlet having a threaded connection end for threading a joint of a high-pressure fuel supply pipe (not shown) connected to the high-pressure fuel pump. There is. Further, the cylindrical body of the delivery pipe is provided with a plurality of bolt holes for fixing the delivery pipe to the cylinder head of the internal combustion engine.

JP2007-54884

By the way, in the above-mentioned delivery pipe, the high-pressure fuel supply pipe is designed so that it can be attached to the threaded end of the fuel inlet of the joint part of the high-pressure fuel supply pipe, which is optimal for changing the engine layout of an internal combustion engine. There is one in which the fuel inlet port, which is the connection part with the pipe, is positively inclined with respect to the longitudinal direction of the delivery pipe, so that the threaded connection end protrudes in an inclined position.
In that case, the fuel inlet has a complicated shape that protrudes from the delivery pipe at an angle with respect to its axial direction, making it very complicated to mold the fuel inlet and the delivery pipe integrally. becomes difficult.

Therefore, currently, apart from the delivery pipe, the fuel introduction inlet (hereinafter referred to as the inlet), which is the connecting part of the high-pressure fuel supply pipe, is formed by hot forging, and then the threads are machined and the communication hole is machined in the subsequent process. The inlet is attached to one end of the delivery pipe.
In that case, the cylindrical forming material The cylindrical molding material A burr 20a comprising a fuel introduction shaft 23 having a columnar threaded connection end 21a, and a mounting leg 24 for attaching to a delivery pipe that protrudes from one end side of the fuel introduction shaft 23 perpendicularly to the axial direction thereof. A solid molded body 20A is molded. At this time, the burr 20a of the solid molded body 20A is formed thickly at the entire circumferential position on the center line that divides the fuel introduction shaft part 23 and the mounting leg part 24 into two symmetrical shapes. Next, in the second step of hot forging, the burr 20a portion is removed from the solid molded body 20A with burrs by punching to form a solid molded body 20A having the outer shape of the inlet shown in FIG. 15(C). . Thereafter, the solid molded body 20A is cooled, scale is removed by shot blasting in a post-process, and a thread is machined to the cylindrical threaded joint end 21a and communicated with the fuel inlet to the fuel inlet shaft 23. The inlet is formed into a desired shape by performing hole processing.
The inlet is attached by welding, brazing, etc., with the fuel introduction shaft portion 23 projecting obliquely relative to the axial direction of the delivery pipe.
However, in the case where the inlet is formed by hot forging as described above, the solid molded body 20A with burrs is first formed by forging to remove burrs in the first step, and then the solid body with burrs is formed in the second step. Since the solid molded body 20A is formed by removing the burr 20a from the molded body 20A by punching, there is a problem in that a large parting line remains on the solid molded body 20A, and in addition, there is a problem in that the parting line remains large during hot forging. The dimensions of the solid molded body 20A tend to vary, and due to the variation in dimensions, the holding posture and retention of the solid molded body 20A by chucks, etc. when machining screws, fuel inlets and communication holes in the post-process are difficult. There was a problem that the force was not constant and the repeatability during post-process processing was low. Moreover, in hot forging, the life of the mold is short, and since the burr 20a portion is removed, there is a lot of material loss of the forming material X, making it uneconomical as a whole.

Therefore, the present invention was invented in order to solve the above-mentioned conventional drawbacks.In addition to the delivery pipe, which has a plurality of insertion parts for attaching fuel injection valves, the present invention serves as a connection part for a high-pressure fuel supply pipe. When molding a fuel introduction inlet with a complex shape, it is possible to mass-produce high-precision solid inlet molded bodies by having no or as thin a parting line as possible, and minimizing variation in overall dimensions despite large volume movement. This makes it possible to securely hold the molded object and form screws and communicating holes with high repeatability during post-process processing, while also extending the life of the mold and reducing costs by eliminating material loss. The object of the present invention is to provide a method for manufacturing a fuel introduction inlet.

The invention according to claim 1 of the present application is a method for manufacturing a fuel introduction inlet to be attached to a delivery pipe having a fuel passage and a plurality of insertion portions for attaching fuel injection valves. Using a cold forging machine equipped with a fixed half mold having a half forming recess made of cemented carbide or high speed steel and a half movable mold having a half forming recess, these halves are A cylindrical molded material is cold-forged from the axial direction using a movable mold and a fixed half-split mold to form a fuel introduction shaft having a cylindrical threaded connection end at the tip, and a rear end of the fuel introduction shaft. A solid molded body is formed with a mounting leg for the delivery pipe that protrudes from the lower part at an angle perpendicular or obtuse to the axial direction of the fuel introduction shaft, and then the solid molded body is cold-rolled. After taking it out of the forging machine, in a post-process, the outer periphery of the cylindrical threaded end of the molded body is threaded to form a threaded end, and a fuel inlet is formed in the center of the threaded end. The present invention is characterized in that a communication hole is formed that communicates with the fuel inlet and opens on the side surface of the rear end side of the fuel inlet shaft to communicate the fuel inlet with the fuel passage.

The invention according to claim 2 of the present application is the method for manufacturing a fuel introduction inlet according to claim 1 of the present application, in which the cylindrical threaded joint end is connected to the tip of the fuel introduction shaft through a stepped part. On the other hand, the diameter of the cylindrical forming material is the same or smaller than that of the cylindrical screw connection end, and the forming material is cold forged from the axial direction to reduce the load. When it hangs, the volume of the molding material is transferred to the fuel introduction shaft molding part and the mounting leg molding part in both molds at once by using the gap space due to the shaft diameter difference between the molding material and the fuel introduction shaft part. , the fuel introduction shaft and the mounting leg protruding from the lower rear end of the fuel introduction shaft are simultaneously molded.

According to the method for manufacturing a fuel introduction inlet of the present invention, the inlet formed separately from the delivery pipe is formed into a cylindrical shape by a cold forging machine whose mold is made of cemented carbide or high-speed steel. Since the material is cold-forged from the axial direction, the parting line of the cold-forged solid molded product can be zero or as thin as possible, and the overall dimension variation is small and high precision can be achieved. It is possible to mass produce actual molded objects. As a result, it can be stably and accurately held in a chuck for machining in the subsequent process, and the repeatability during machining of screws and communicating holes can be significantly increased and machining quality can be maintained. In addition, cold forging can extend the life of the mold and at the same time reduce the loss of forming material, resulting in lower costs overall.

In addition, while the cylindrical threaded joint end is set to have a smaller diameter than the fuel introduction shaft through a step at the tip of the fuel introduction shaft, the cylindrical threaded joint end at the fuel introduction shaft is set as a cylindrical molded material. If you use one with the same diameter or a smaller diameter than the shaft diameter of the fuel introduction shaft, the material will be cold forged from the axial direction and the load will be applied to the material. At this point, a large volume movement of the molding material to the fuel introduction shaft molding part and the mounting leg molding part in both molds is carried out using the gap space due to the shaft diameter difference between the molding material and the fuel introduction shaft part. By doing so, the fuel introduction shaft portion and the mounting leg portion protruding from the lower rear end of the fuel introduction shaft portion can be formed simultaneously and at once. As a result, we have created a solid molded body with a fuel introduction shaft having a cylindrical screw connection end and a mounting leg protruding from the lower rear end of the fuel introduction shaft, with less variation in overall dimensions and higher height. It is possible to mold solid molded objects with high precision.

FIG. 2 is a partially omitted perspective view of a delivery pipe to which an inlet manufactured by the manufacturing method according to the present invention is attached. FIG. 2 is a side view of an inlet manufactured by the manufacturing method according to the present invention. It is a front view of the same inlet. It is a front view center vertical cross-sectional view of the same inlet. It is an explanatory view showing the cold forging state of the same inlet. FIG. 3 is a front view of a cylindrical molded material. FIG. 2 is a side view of a cold-forged solid molded body. FIG. 7 is a side view of an inlet with a mounting leg having a different shape. It is a front view of the same inlet. It is a front view center vertical cross-sectional view of the same inlet. It is an explanatory view showing the cold forging state of the same inlet. FIG. 3 is a side view of the same cold-forged solid molded body. It is an explanatory view showing another closed cold forging state. It is an explanatory view showing still another closed cold forging state. It is a conventional explanatory diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the method for manufacturing a fuel introduction inlet according to the present invention will be described below with reference to the drawings.

First, FIG. 1 shows a delivery pipe 1 for an internal combustion engine equipped with an inlet 10 manufactured by the manufacturing method of the present invention.
The delivery pipe 1 is a cast body having a cylindrical shape, and has a cylindrical body portion 1a having a fuel passage (not shown).In the longitudinal direction thereof, an insertion portion 2 for attaching a fuel injection valve (not shown) is provided. 2 are provided at predetermined intervals, and each insertion portion 2...2 is provided with an insertion port 2a...2a that communicates with the fuel passage of the cylindrical body portion 1a of the delivery pipe 1, and the insertion port 2a... ...The rear end of the fuel injection valve is inserted into 2a. Further, the cylindrical body portion 1a of the delivery pipe 1 is provided with a plurality of bolt holes 3 for fixing the delivery pipe 1 to the cylinder head of an internal combustion engine.
One end of the delivery pipe 1 is a part to which a tip 5 of a high-pressure fuel supply pipe 4 connected to a high-pressure fuel pump (not shown) is fixed with a screw connection. A fuel introduction inlet 10 is separately provided by welding or brazing.

As shown in FIGS. 2 to 4, the inlet 10 is a forged body formed separately from the delivery pipe 1 by a cold forging machine whose mold is made of cemented carbide or high speed steel.
Specifically, as shown in FIGS. 2 to 4, the cylindrical fuel introduction shaft has a threaded joint end 11 at its tip that serves as a connection part for the high-pressure fuel supply pipe 4, and a fuel introduction port 12 at its center. 13, and a mounting leg 14 (projecting downward in FIGS. 2 to 4) for the delivery pipe 1 that protrudes laterally from the intermediate portion in the longitudinal direction of the fuel introduction shaft 13 at right angles to the axial direction. ) on the rear end side of the fuel introduction shaft 13, and when the fuel introduction shaft 13 is attached to the delivery pipe 1 via the mounting leg 14, the fuel introduction port 12 is connected to the fuel passage of the delivery pipe 1. A communication hole 15 is formed for communication.

As shown in FIG. 1, the inlet 10 is attached to one end of the delivery pipe 1 by welding, brazing, etc. in an attitude inclined with respect to its longitudinal direction. By attaching the inlet 10 to one end of the delivery pipe 1 with the inlet 10 inclined relative to the delivery pipe 1 in this way, it can be widely adapted to changes in the engine layout of internal combustion engines, and maintains high pressure in an optimal state. The tip 5 of the fuel supply pipe 4 can be attached to the threaded end 11 of the fuel introduction shaft 13.
Furthermore, when the inlet 10 is attached to one end of the delivery pipe 1 by, for example, welding in an inclined position with respect to the delivery pipe 1, the fuel inlet 12 of the inlet 10 is connected to the fuel inlet of the delivery pipe 1 through the communication hole 15. It will be connected to the passage without any leakage.

Thereby, the fuel supplied from the high-pressure fuel supply pipe 4 passes through the fuel passage of the cylindrical body portion 1a of the delivery pipe 1 from the fuel introduction port 12 of the inlet 10 through the communication hole 13, and passes through each insertion portion 2...2. The fuel is distributed to each fuel injection valve through the insertion ports 2a...2a, and is supplied into the fuel chamber of the engine.

Next, a method for manufacturing the fuel introduction inlet 10 formed and used as described above will be described.
As a manufacturing method of this inlet 10, first, as shown in FIG. Using a cold forging machine 30 equipped with a half-split movable mold (punch) 32 having a forming recess 32a, the half-split fixed mold 31 and the half-split movable mold 32 are used to form a mold as shown in FIG. A cylindrical forming material X is cold forged from its axial direction to form a fuel introduction shaft 13 having a cylindrical threaded connection end 11a at the tip shown in FIG. 7, and a longitudinally intermediate portion of the fuel introduction shaft 13. A solid molded body 10A having a mounting leg portion 14 for attaching to the delivery pipe 1 protruding perpendicularly to the axial direction thereof is molded.
Here, in FIG. 5, the dotted line on the solid molded body 10A indicates the abutting surface between the lower half-split fixed mold 31 and the upper half-split movable mold 32 when molding the solid molded body 10A. This abutment surface is formed on an extension of a horizontal line that roughly divides the thickness of the mounting leg 14 into upper and lower halves in FIG. A molding space is formed for the lower half of the solid molded body 10A, and a molding space for the upper half of the solid molded body 10A is formed by the molding recess 32a formed on the bottom of the movable half mold 32. are doing. Then, with the molding material X interposed between the lower half-split fixed mold 31 and the upper half-split movable mold 32, the upper half-split movable mold 32 is replaced with the lower half-split fixed mold. The molding material X is moved to the mold 31 side and cold forged by the forming force and closing force of the half-split fixed mold 31 and the half-split movable mold 32 into the desired shape in which the mounting leg 14 is laterally drawn out. An actual molded body 10A is molded.

Thereafter, the solid molded body 10A formed as shown in FIG. Cutting is performed to form a threaded joint end 11 as shown in FIG. 2, and a hole is suitably drilled in the center of the threaded joint end 11 using a drilling machine (not shown) to form a fuel inlet 12. Furthermore, a communication hole 15 is formed which communicates with this fuel inlet 12 and opens on the side surface of the rear end side of the fuel inlet shaft portion 13 to communicate the fuel guide 12 with the fuel passage of the delivery pipe 1. A fuel introduction inlet 10 is formed.

As described above, according to the method for manufacturing a fuel introduction inlet of the present invention, the inlet 10 formed separately from the delivery pipe is formed into a cylindrical shape using a cold forging machine whose mold is made of cemented carbide or high-speed steel. Since the material It is possible to mass produce 10A of solid molded bodies with high precision. As a result, it can be stably and accurately held in a chuck for machining in the subsequent process, and the repeatability during machining of screws and communicating holes can be significantly increased and machining quality can be maintained. In addition, cold forging can extend the life of the mold and at the same time reduce the loss of forming material, resulting in lower costs overall.
Even if the parting line of the solid molded body appears slightly thin, it can be easily removed by barrel processing, etc., and it can be stably held in a cutting chuck in the next process, maintaining processing quality.

In addition, in the embodiment described above, the cylindrical threaded joint end 11a is set at the tip of the fuel introduction shaft 13 via a stepped part to have a smaller diameter than the fuel introduction shaft 13, and the cylindrical molded material is The diameter is the same as or smaller than the shaft diameter of the cylindrical threaded connection end 11a of the introduction shaft 13, that is, the diameter is set smaller than the shaft diameter of the fuel introduction shaft 13. In this case, when the forming material is cold forged from its axial direction and a load is applied to the forming material, the gap space due to the difference in shaft diameter between the forming material and the fuel introduction shaft portion 13 is utilized. A large volume movement of the molding material to the fuel introduction shaft molding portion and the mounting leg molding portion in both molds is performed at once, and the fuel introduction shaft portion 13 and the fuel introduction shaft portion 13 protrude from the lower rear end thereof. The mounting leg portion 14 can be simultaneously molded in one go. As a result, the solid molded body 10A, which includes the fuel introduction shaft 13 having the cylindrical threaded joint end 11a and the mounting leg 14 protruding from the lower rear end of the fuel introduction shaft 13, can be manufactured without variations in overall dimensions. A smaller, more precise solid molded body 10A can be molded.

Further, in the above-described embodiment, the inlet 10 is provided with the attachment leg portion 14 to the delivery pipe 1 (laterally extending) that protrudes perpendicularly to the axial direction of the fuel introduction shaft portion 13. , for example, as shown in FIGS. 8 to 10, from a longitudinally intermediate portion of the fuel introduction shaft 13 to a delivery pipe 1 that projects obliquely at an obtuse angle with respect to the axial direction of the fuel introduction shaft 13. The inlet 10 having the mounting leg portion 14 (projecting downward in FIGS. 8 to 10) is also manufactured by the manufacturing method of the present invention using the cold forging machine 30 shown in FIG. 11 in the same manner as in the previous embodiment. It is possible to obtain similar effects.

In that case, the portion indicated by the dotted line in the solid molded body 10B in FIG. 11 represents the abutment surface between the lower half-split fixed mold 31 and the upper half-split movable mold 32. In other words, this abutment surface is formed by an inclined line that roughly divides the thickness of the mounting leg 14 that projects obliquely into two in the thickness direction in FIG. It will be formed on the line connecting the . The molding hole 31a of the fixed half mold 31 and the knockout pin 33 form a molding space for the lower half of the solid molded body 10B, and a molding recess formed on the bottom of the movable half mold 32 32a forms a molding space for the upper half of the solid molded body 10A.

In addition, in the solid molded body 10B in FIG. 12, both sides of the fuel introduction shaft portion 13 are shaped into an oval shape with flat surfaces 13a, 13a. It is possible to perform secondary processing such as screw processing and cutting with high precision after firmly fixing the product using the chuck on the table side.

Furthermore, the term "cold forging" in the present invention is a concept that includes not only the cold forging having the structure of the above-described embodiments but also closed cold forging. Therefore, as another embodiment, for example, as shown in FIGS. 13 and 14, each of the half-split movable molds 31 in the cold forging machine 30 of the two embodiments described above has a half-split recess 31a side. It has a closed cold forging structure with a built-in movable forming pin 34 that moves forward and backward, and after applying a closing force by pressing the half-split movable mold 31 to the half-split fixed mold 31 during cold forging, Further, a forming force is applied by advancing (downwardly moving) the movable forming pin 34 toward the half-split recess 32a to perform closed cold forging, thereby forming the solid formed body 10A or the solid formed body 10B. You can.

Further, in the above-mentioned embodiments, the above-mentioned solid molded body 10A or 10B is formed in one stage of cold forging process, but this is not limited to the above-mentioned embodiments. Rather, a multi-stage cold forging process is performed, for example, preforming one end of the cylindrical forming material You can do it like this.

1 Delivery pipe 1a Cylindrical body 2 Insertion part 2a Insertion port 10 Fuel introduction inlet 10A Solid molded body 10B Solid molded body 11 Threaded joint end 11a Cylindrical screw joint end 12 Fuel introduction port 13 Fuel introduction shaft part 14 Mounting leg 15 Communication hole X Molding material

Claims (2)

A method for manufacturing a fuel introduction inlet in a delivery pipe having a fuel passage and a plurality of insertion portions for attaching fuel injection valves, the method first involves forming a mold in half made of cemented carbide or high-speed steel. Using a cold forging machine equipped with a half-split fixed mold having a forming recess and a half-split movable mold having a half-split forming recess, these half-split movable molds and half-split fixed molds are used. A cylindrical forming material is cold forged from the axial direction, and a fuel introduction shaft having a cylindrical screw connection end at the tip and a fuel introduction shaft from the lower rear end of the fuel introduction shaft in the axial direction of the fuel introduction shaft are formed. A solid molded body is formed with mounting legs for the delivery pipe that protrude at right angles or obtuse angles, and then the solid molded body is taken out of the cold forging machine, and in a post-process, the molded body is The outer periphery of the cylindrical threaded joint end is threaded to form a threaded joint end, and at the same time, a fuel inlet is formed in the center of the threaded joint end. 1. A method of manufacturing a fuel introduction inlet, characterized in that a communication hole is formed in an end side surface and communicates a fuel introduction port with a fuel passage. The cylindrical screw connection end is set to have a smaller diameter than the fuel introduction shaft through a step at the tip of the fuel introduction shaft, while the shaft diameter of the cylindrical molded material is the same as the shaft diameter of the cylindrical screw connection end. When the forming material is cold forged from the axial direction using a material with the same diameter or a smaller diameter, when a load is applied to the forming material from the axial direction, the space created by the difference in shaft diameter between the forming material and the fuel introduction shaft is used to The volume is transferred to the fuel introduction shaft molding portion and the mounting leg molding portion of the mold at once, and the fuel introduction shaft and the mounting leg protruding from the lower rear end of the fuel introduction shaft are simultaneously molded. The method of manufacturing a fuel introduction inlet according to claim 1, characterized in that the method is characterized in that:

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