JP2014008638A - Method for molding delivery pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve transferability and surface roughness on the inner wall surface of a base end part of an injector fitting part.SOLUTION: A delivery pipe 10 made of a resin is injection-molded, which includes a pipe body part 11 having a fuel passage 14, and a plurality of injector fitting parts 12 each having a fuel supply port 16 for distributing a fuel introduced into the fuel passage 14 of the pipe body part 11 into a plurality of injectors. In a molding tool 20 for forming a cavity 21 of the delivery pipe 10, a degassing passage 34 opened to a die matching surface 31 abutting on a core 26 for the fuel passage is formed in a core 28 for the fuel supply port forming the fuel supply port 16. The delivery pipe 10 is injection-molded by using the molding tool 20 including the core 28 for the fuel supply port in which the degassing passage 34 is formed.

Description

  The present invention relates to a delivery pipe molding method for injection molding a resin delivery pipe that distributes fuel to a plurality of injectors.

  Conventionally, a delivery pipe, also referred to as a fuel distribution pipe, includes a pipe body portion having a fuel passage and a plurality of injector mounting portions having fuel supply ports for distributing fuel introduced into the fuel passage of the pipe body portion to the plurality of injectors. Prepare. A molding die that forms a cavity of a delivery pipe includes a fuel passage core that forms a fuel passage and a fuel supply port core that forms a fuel supply port. A delivery pipe is injection-molded using the mold (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 5-44594

  During injection molding of the delivery pipe, the shape of the delivery pipe 10 that is a molded product (described later) causes a gas pool (gas pocket) at the proximal end of the injector mounting portion, that is, the peripheral portion of the mold matching surfaces of both cores. Is likely to occur. Therefore, there has been a problem that transferability and surface roughness on the inner wall surface of the base end portion of the injector mounting portion are poor.

  The problem to be solved by the present invention is to provide a delivery pipe molding method capable of improving transferability and surface roughness on the inner wall surface of the proximal end portion of the injector mounting portion.

The above-mentioned problem can be solved by a method for forming a delivery pipe having the structure described in the claims.
According to the method for forming a delivery pipe according to claim 1, a plurality of injectors having a pipe body portion having a fuel passage and a fuel supply port for distributing fuel introduced into the fuel passage of the pipe body portion to the plurality of injectors. A delivery pipe molding method for injection molding of a resin delivery pipe having a mounting portion, a fuel path core forming a fuel path in a molding die for forming a delivery pipe cavity, and a fuel supply port At least one of the cores for the fuel supply port that forms a gas vent passage is formed in the die-matching surface that is in contact with the other core. The delivery pipe is injection-molded using the mold provided. According to this configuration, at the time of injection molding, the gas that tends to accumulate around the mold-matching surfaces of both cores passes through the gap that exists between the mold-matching surfaces of both cores, and is contained in at least one of the cores. The gas can be extracted or discharged through a gas vent passage formed in the child. Thereby, the transferability and surface roughness on the inner wall surface of the base end portion of the injector mounting portion can be improved. As a result, the quality of the delivery pipe can be improved.

  Moreover, generation | occurrence | production and accumulation | storage of the resin mist resulting from the temperature rise of the gas by the adiabatic compression in the peripheral part of the die-matching surface of both cores can be prevented. Further, when the mold is opened, the mold matching surfaces of both the cores are opened, so that the resin burrs and resin burrs generated between the mold matching surfaces of both the cores can be easily removed. Therefore, it is possible to prevent the transferability and surface roughness of the inner wall surface of the base end portion of the injector mounting portion from being deteriorated due to accumulation of deposits such as resin resin and resin burrs. At the same time, the number of washings of both cores can be reduced, productivity can be improved and manufacturing cost can be reduced. Also, by opening the gas vent passage in the mold matching surface, unlike the case of opening the gas vent passage to the cavity, no resin burr is generated in the opening end of the gas vent passage.

  According to the method for forming a delivery pipe according to claim 2, the opening formed in the die-matching surface has an opening area larger than the passage cross-sectional area of the gas vent passage in the core in which the gas vent passage is formed. A recess is formed. Therefore, the contact area between the mold-matching surfaces of both cores can be reduced, and the generation of resin burrs and resin burrs between the mold-matching surfaces of both cores can be reduced. Further, the passage length of the gas vent passage excluding the opening recess can be shortened.

  Further, according to the method for forming a delivery pipe according to claim 3, the gas vent passage formed in the core for the fuel supply port opens at the center portion of the die-matching surface and is relative to the axis of the core. It is formed in an inclined straight line. Therefore, for example, a straight gas vent passage can be formed so as not to interfere with the cooling circuit formed at the center of the fuel supply port core.

It is sectional drawing which shows the delivery pipe concerning Embodiment 1. FIG. It is a bottom view which shows a delivery pipe. It is sectional drawing which shows a shaping | molding die. It is sectional drawing which shows the principal part of a shaping | molding die. It is a top view which shows the core for fuel supply ports. It is sectional drawing which shows the principal part of the shaping | molding die concerning Embodiment 2. FIG. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. It is sectional drawing which shows the principal part of the shaping | molding die concerning Embodiment 3. FIG.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Embodiment 1]
Embodiment 1 will be described. In the present embodiment, for example, a method for forming a delivery pipe used for an in-line three-cylinder internal combustion engine (engine) is illustrated. For convenience of explanation, after explaining a delivery pipe and a shaping | molding die, a shaping | molding method is demonstrated. FIG. 1 is a sectional view showing a delivery pipe, and FIG. 2 is a bottom view of the same. For convenience of explanation, the top, bottom, left, and right of the delivery pipe are determined based on the cross-sectional view of FIG.

  As shown in FIG. 1, the delivery pipe 10 is made of resin, and includes a pipe main body portion 11 that is a main body, and three pipes arranged at predetermined intervals in the axial direction (left and right direction in FIG. 1) of the pipe main body portion 11. And an injector mounting portion 12. The injector mounting portion 12 protrudes from the pipe main body portion 11 in the radial direction (downward in FIG. 1), and an injector (not shown) can be mounted. The inner peripheral surface of the pipe body 11 is formed in a tapered shape that becomes thinner from the base end (left end in FIG. 1) toward the tip (right end in FIG. 1). Moreover, the outer peripheral surface of the pipe main-body part 11 is formed in straight shape. Further, a fuel passage 14 is formed in the pipe body 11 with its tip end (right end in FIG. 1) closed. Further, a pipe member (not shown) of a fuel supply system in the internal combustion engine can be connected to a base end portion, that is, an open end portion (left end portion in FIG. 1) of the pipe main body portion 11.

  A fuel supply port 16 communicating with the fuel passage 14 is formed in each injector mounting portion 12. Further, a partition wall 17 having an opening 18 is formed in the proximal end portion of the injector mounting portion 12 (see FIG. 2). The opening hole 18 corresponds to the opening end of the fuel supply port 16 on the fuel passage 14 side. Moreover, the opening hole 18 is formed as a long hole that lengthens the left-right direction. In addition, the opening hole 18 of the partition wall 17 should just be able to ensure a required opening area, and may be shapes, such as a round hole, a semicircle hole, an elliptical hole, a square hole, and a deformed hole, besides a long hole. Further, the partition wall 17, for example, regulates the flow of fuel and the transmission of pressure fluctuations to the fuel passage 14, and prevents the O-ring (not shown) attached to the injector from falling off.

Next, a mold for the delivery pipe 10 will be described. FIG. 3 is a cross-sectional view showing a mold. For convenience of explanation, the upper, lower, left, and right sides of the mold are determined according to the upper, lower, left, and right sides of the delivery pipe 10. The orientation in the mold is set for convenience of explanation, and does not limit the arrangement direction of the mold.
As shown in FIG. 3, the molding die 20 includes a fixed die 22, a movable die 24, a fuel passage core 26, and three fuel supply port cores 28, and the delivery is performed by clamping the die. A cavity 21 of the pipe 10 (see FIG. 1) is formed.

  The fixed mold 22 and the movable mold 24 are for molding the outer surfaces of the pipe main body 11 and the injector mounting portions 12 of the delivery pipe 10 (see FIG. 1). That is, the fixed mold 22 corresponds to an upper mold, and has a molding surface corresponding to the outer surface of the upper half of the pipe body 11 on the lower surface side. The fixed mold 22 is provided with a gate 23 communicating with the cavity 21. The movable mold 24 corresponds to a lower mold and can be aligned and opened in the vertical direction with respect to the fixed mold 22. The movable mold 24 has a molding surface corresponding to the outer surface of the lower half portion of the pipe body 11 and the outer surface of each injector mounting portion 12 on the upper surface side.

  The fuel passage core 26 forms the inner wall surface of the fuel passage 14 of the delivery pipe 10 (see FIG. 1), and is formed in a round bar shape and a tapered shape. The core 28 for the fuel supply port is for forming the inner wall surface of the fuel supply port 16 of the delivery pipe 10 and is formed in a stepped columnar shape. Further, a protruding portion 30 for forming the opening hole 18 of the partition wall 17 of the delivery pipe 10 protrudes from the tip end portion (upper end portion) of the fuel supply port core 28.

Next, the gas venting structure of the mold 20 for discharging the gas in the cavity 21 during the injection molding of the delivery pipe 10, particularly the gas in the cavity portion corresponding to the injector mounting portion 12 will be described. 4 is a cross-sectional view showing the main part of the mold, and FIG. 5 is a top view showing the core for the fuel supply port.
As shown in FIG. 4, the cavity portion corresponding to the lower end portion of the injector mounting portion 12 of the delivery pipe 10 includes a core fitting hole (reference numeral 25) attached to the movable die 24 and a core fitting hole 25 thereof. Is opened to the outside (atmosphere) through an annular gap existing between the fitting surface of the fuel supply port core 28 fitted to the large diameter shaft portion 29. Also, the upper end surface (tip surface) 31 of the convex portion 30 of the fuel supply port core 28 and the lower side surface 27 of the fuel passage core 26 corresponding to the upper end surface 31 of the convex portion 30 contact each other. It is a so-called mold-matching surface. For this reason, the upper end surface 31 of the convex portion 30 is referred to as a mold matching surface 31 (same as the upper end surface), and the lower side surface 27 of the fuel passage core 26 is referred to as the mold matching surface (same reference numeral as the lower side surface). That's it.

  The fuel supply port core 28 is formed with a straight gas vent passage 34 that opens to a die-matching surface 31 that contacts the fuel passage core 26. The lower end of the gas vent passage 34 is open to the outside (atmosphere). In addition, the die-matching surface 31 of the convex part 30 is formed with an open concave part 35 having a bottomed horizontally-long rectangular hole having an opening area larger than the cross-sectional area of the gas vent passage 34. The opening recess 35 is formed by cutting, for example.

  As shown in FIG. 5, the mold matching surface 31 of the convex portion 30 is formed in a horizontally long rectangular frame shape by the formation of the opening concave portion 35. A vent groove 36 is formed in the mold matching surface 31 of the convex portion 30 so as to cross in the left-right direction and the front-rear direction. The vent groove 36 is formed with a depth (for example, a depth of about 10 to 20 μm) through which the resin material does not pass or hardly passes but the gas passes. The vent groove 36 is formed by, for example, grinding.

  As shown in FIG. 4, a linear cooling circuit 40 is formed at the center of the fuel supply port core 28. The cooling circuit 40 is a passage for flowing a cooling liquid (for example, cooling water) and is formed in a hollow hollow cylindrical shape. For this reason, the gas vent passage 34 opens in the center of the die-matching surface 31 of the convex portion 30, that is, in the opening concave portion 35 so as not to interfere with the cooling circuit 40, and with respect to the axis of the fuel supply core 28 It is formed in an inclined straight line. The gas vent passage 34 and the cooling circuit 40 are formed, for example, by drilling with a drill or the like.

Next, a molding method for injection molding the delivery pipe 10 using the molding die 20 will be described.
As shown in FIG. 3, the fuel passage core 26 is inserted into the molding space formed by the two dies 22, 24 in a state where the movable die 24 is matched with the fixed die 22. Further, the fuel supply port core 28 is inserted into the movable mold 24, and the mold matching surface 31 of the convex portion 30 of the fuel supply port core 28 contacts the mold matching surface 27 of the fuel passage core 26. That is, the molds are matched (see FIG. 4). In this manner, the cavity 21 for molding the delivery pipe 10 is formed by the fixed mold 22, the movable mold 24, the fuel passage core 26, and the fuel supply cores 28 that are clamped. The delivery material 10 is injection-molded by injecting a resin material (molten resin) into the cavity 21 from the gate 23 (see FIG. 3) of the fixed mold 22. Further, after the injection-molded resin material is cooled, each fuel supply port core 28 and the fuel passage core 26 are extracted, and the movable mold 24 is opened, so that a delivery pipe as a molded product is obtained. 10 is taken out.

  By the way, at the time of injection molding of the delivery pipe 10 by the molding die 20 (see FIG. 4), the resin material injected from the gate 23 (see FIG. 3) is the tip (upper end) of the core 28 for the fuel supply port. After being split at, it joins on the opposite gate side (right side in FIG. 4). At this time, a closed space divided up and down by the joining portion of the resin material is formed. The closed space below the merging portion is interposed through an annular gap that exists between the fitting surface between the core fitting hole 25 of the movable mold 24 and the large-diameter shaft portion 29 of the core 28 for the fuel supply port. Since the gas is open to the outside (atmosphere), the gas that accumulates in the closed space can escape to the outside (atmosphere).

On the other hand, on the upper side of the resin material merging portion (the peripheral portion of the convex portion 30 of the fuel supply port core 28, that is, the peripheral portion of the mold matching surface between the fuel passage core 26 and the fuel supply port core 28). Since the closed space is conventionally a sealed space, gas accumulation occurs, and transferability and surface roughness on the inner wall surface of the proximal end portion of the injector mounting portion 12 are reduced. This phenomenon is caused by the shape of the delivery pipe 10 that is a molded product.
However, according to the present embodiment, the gas supply passage 34 including the opening recess 35 is formed in the core 28 for the fuel supply port. For this reason, the gas that tends to accumulate in the closed space above the joining portion of the resin material (the space around the die-matching surface between the fuel passage core 26 and the fuel supply port core 28) From the gap (including the vent groove 36) existing between the mold matching surfaces 27, 31 of both the cores 26, 28, through the gas vent passage 34 including the opening recess 35 of the core 28 for the fuel supply port It can escape to (atmosphere).

  According to the molding method of the delivery pipe 10, the gas that tends to accumulate around the mold matching surfaces 27, 31 of both the cores 26, 28 during the injection molding is used as the mold matching surfaces 27, 28 of both the cores 26, 28. From the gap (including the vent groove 36) existing between 31, the gas can be extracted or discharged through a gas vent passage 34 (including the opening recess 35) formed in the fuel supply port core 28. Thereby, the transferability and surface roughness at the inner wall surface of the proximal end portion of the injector mounting portion 12, that is, the hole edge portion of the opening hole 18 of the partition wall 17, can be improved. As a result, the quality of the delivery pipe 10 can be improved.

  In the present embodiment, since the vent groove 36 is formed in the mold matching surface 31 of the convex portion 30 of the fuel supply port core 28, the peripheral portions of the mold matching surfaces 27 and 31 of both the cores 26 and 28 are formed. The gas to be stored in the gas can be quickly extracted into the opening recess 35 of the gas vent passage 34. The vent groove 36 may be provided as necessary and may be omitted.

  Moreover, generation | occurrence | production and accumulation | storage of the resin mist resulting from the temperature rise of the gas by the adiabatic compression in the peripheral part of the type | mold matching surfaces 27 and 31 of both the cores 26 and 28 can be prevented. In addition, when the mold is opened, the mold matching surfaces 27 and 31 of both the cores 26 and 28 are opened, so that the resin burrs and resin splines generated between the mold matching surfaces 27 and 31 of both the cores 26 and 28 are removed. It can be easily removed. Therefore, deterioration of transferability and surface roughness on the inner wall surface of the base end portion of the injector mounting portion 12 (hole edge portion of the opening hole 18 of the partition wall 17) due to accumulation of deposits such as resin burrs and resin burrs is prevented. be able to. At the same time, the number of washings of both the cores 26 and 28 can be reduced to improve the productivity and reduce the manufacturing cost. Unlike the case where the gas vent passage 34 is opened in the cavity 21 by opening the gas vent passage 34 in the mold matching surface 31 of the convex portion 30 of the fuel supply port core 28, the open end of the gas vent passage 34 is provided. Resin burrs are not generated in the part.

  In addition, the fuel supply port core 28 in which the gas vent passage 34 is formed is formed with an opening recess 35 that opens in the mold matching surface 31 with an opening area larger than the passage cross-sectional area of the gas vent passage 34. Accordingly, the contact area between the mold matching surfaces 27 and 31 of the cores 26 and 28 is reduced, and the generation of resin burrs and resin burrs between the mold matching surfaces 27 and 31 of the cores 26 and 28 is reduced. Can do. Further, the passage length of the gas vent passage 34 excluding the opening recess 35 can be shortened.

  Further, the gas vent passage 34 formed in the core 28 for the fuel supply port is formed in a linear shape that opens at the center of the mold matching surface 31 and is inclined with respect to the axis of the core 28. Therefore, for example, the straight gas vent passage 34 can be formed so as not to interfere with the cooling circuit 40 formed at the center of the fuel supply port core 28.

[Embodiment 2]
A second embodiment of the present invention will be described. Since the present embodiment is obtained by changing a part of the first embodiment, the changed portion will be described and redundant description will be omitted. 6 is a cross-sectional view showing the main part of the mold, and FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG.
As shown in FIG. 7, in the present embodiment, the fuel supply port core 28 in the first embodiment is divided into two in the front-rear direction. A split groove portion of the gas vent passage 34 (including the opening recess 35) and a split groove portion of the cooling circuit 40 are formed on the split surfaces of both the split bodies 28A and 28B (see FIG. 6). . The divided surfaces of both divided bodies 28A and 28B are joined together by adhesion or the like. According to the present embodiment, the degree of freedom in designing the gas vent passage 34 can be increased. Therefore, for example, the gas vent passage 34 can be formed in a polygonal line having a plurality of bends so as to bypass the cooling circuit 40 (see FIG. 6).

[Embodiment 3]
Embodiment 3 of the present invention will be described. Since the present embodiment is obtained by changing a part of the first embodiment, the changed portion will be described and redundant description will be omitted. FIG. 8 is a cross-sectional view showing the main part of the mold.
As shown in FIG. 8, in this embodiment, the opening concave portion 35 in the fuel supply port core 28 in the first embodiment is omitted, and the upper end opening portion of the gas vent passage 34 is directly on the die-matching surface 31 of the convex portion 30. Open. Further, the gas vent passage 34 is disposed at a position away from the gate 23 (see FIG. 3), that is, on the opposite gate side (right side in FIG. 8) where gas accumulation is likely to occur. For this reason, the gas which is going to accumulate in the peripheral part of the type | mold matching surfaces 27 and 31 of both the cores 26 and 28 can be rapidly extracted rather than the case where the degassing channel | path 34 is arrange | positioned at the gate side (left side in FIG. 8). it can.

  The present invention is not limited to the above-described embodiments, and modifications can be made without departing from the gist of the present invention. For example, the gas vent passage 34 may be provided in the fuel passage core 26. Further, the opening recess 35 of the gas vent passage 34 is not limited to a horizontally long rectangular shape, but may be a bottomed circular hole shape, other polygonal shapes, or the like.

DESCRIPTION OF SYMBOLS 10 ... Delivery pipe 11 ... Pipe main-body part 12 ... Injector attachment part 14 ... Fuel passage 16 ... Fuel supply port 20 ... Mold 21 ... Cavity 26 ... Core for fuel passage 27 ... Mold matching surface 28 ... Core for fuel supply port 31 ... Mold matching surface 34 ... Gas vent passage 35 ... Opening recess

Claims (3)

A pipe body having a fuel passage;
A delivery pipe molding method for injection molding a resin delivery pipe comprising: a plurality of injector mounting portions having fuel supply ports for distributing fuel introduced into a fuel passage of the pipe main body portion to a plurality of injectors;
In the mold that forms the cavity of the delivery pipe, at least one of the core for the fuel passage that forms the fuel passage, and the core for the fuel supply port that forms the fuel supply port, A gas vent passage is formed in the die-matching surface that is in contact with the core.
A method for forming a delivery pipe, wherein the delivery pipe is injection-molded using the molding die having a core in which the gas vent passage is formed. A method for forming a delivery pipe according to claim 1,
Molding of a delivery pipe, wherein the core in which the gas vent passage is formed is formed with an opening recess that opens in the die-matching surface with an opening area larger than a passage cross-sectional area of the gas vent passage. Method. A method for forming a delivery pipe according to claim 1 or 2,
The delivery port, wherein the gas vent passage formed in the core for the fuel supply port is formed in a linear shape that opens at a center portion of the mold matching surface and is inclined with respect to the axis of the core. Pipe forming method.

Images