JP3063170B2 - Method and apparatus for forming nozzle tip of injection nozzle and injection nozzle manufactured by the method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for manufacturing a tip of an injection nozzle, that is, a nozzle tip from a ceramic material containing ceramic particles and the like, an apparatus therefor, and an injection nozzle manufactured by the molding method.

[0002]

2. Description of the Related Art Conventionally, as a molding method for manufacturing a small precision part such as a tip of an injection nozzle using a ceramic material containing ceramic particles or the like, an injection molding method or a method of slip casting using a wax core is used. A method of heating and eluting a wax core is known.

Further, as a method of casting a slurry of silicon nitride ceramics, there is a method disclosed in Japanese Patent Application Laid-Open No. 64-5977. The molding method comprises adding a polyacrylic acid ammonium salt as a deflocculant to a slurry of silicon nitride ceramics in an amount of 0.1 to 0.7% by weight based on the slurry powder, and adding an acrylic emulsion to the slurry as a binder. It was cast molded.

A fuel injection nozzle for a diesel engine is disclosed in Japanese Utility Model Laid-Open No. 59-21084. The fuel injection nozzle includes a nozzle holder formed of a cylindrical metal holder and a nozzle portion made of a ceramic material located at the tip of the nozzle holder. Further, the valve body portion of the needle valve and the inner surface of the nozzle portion are configured so as not to contact with a small gap.

[0005]

However, in the conventional injection molding method described above, since the composition is filled into the mold by high pressure, for example, a pin (diameter: 0.3 mm) for forming the injection hole of the injection nozzle of a diesel engine is used. ) Etc. may be damaged when pressurized.

Further, the method of heating and eluting the wax core after molding by slip casting has a problem in accuracy, it is not possible to form a highly accurate hole, etc. Cracks may occur. Further, the molding method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 64-5977 has a similar problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and it is possible to form a nozzle having a polygonal shape or the like formed in a spray nozzle with a ceramic material with high precision. A fuel injection nozzle with a small diameter injection hole for use in diesel engines is manufactured by changing the ceramic composition in the height direction of the tip of the tip, that is, the nozzle tip, according to the intended use. When the molded body is fired to produce a sintered body, the joining surface portion is made of Al ₂ O ₃ or Y ₂ O so that the sintered body can be firmly joined to a metal member such as a nozzle body. _{The third} object of the present invention is to provide a method of forming a nozzle tip portion of an injection nozzle which can be made of a material having a rich composition, an apparatus therefor, and an injection nozzle manufactured by the method.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method of forming a nozzle tip having an injection hole and a joining surface for joining to a nozzle body, wherein the outer shape of the nozzle tip is formed. A porous mold forming the joining surface is arranged on a lower surface of a mold having a cavity to be formed,
A step of arranging a hole forming pin for forming the injection hole and a forming pin for forming an inner surface of the tip of the nozzle in the cavity and injecting slurry into the cavity, and causing the porous mold to absorb moisture of the slurry. Forming the injection hole in the inlaid portion by removing the hole forming pin from the inlaid portion in a state where shape retention is developed in the inlaid portion where the slurry is inlaid in the cavity. And a step of causing the porous mold to absorb the moisture of the inlaid portion to solidify the inlaid portion, and a method of forming a nozzle tip of an injection nozzle.

The nozzle tip of the injection nozzle manufactured by this molding method is one in which the shape of the injection hole formed at the nozzle tip is polygonal and made of at least a ceramic material.

Further, in the method of forming a nozzle tip portion of the injection nozzle, the slurry has a composition in which components and constituent concentrations are different, and the slurries having the different compositions are sequentially injected into the cavity, and Forming the inlaid portion of the composition. The nozzle tip of the injection nozzle manufactured by this molding method includes a portion near the joining surface of the nozzle tip with the nozzle body,
The other portions of the nozzle tip are made of materials having different types of components and different composition ratios.

According to another aspect of the present invention, there is provided a molding apparatus for forming a nozzle tip having an injection hole and a joining surface for joining to a nozzle body, wherein a cavity for forming an outer shape of the nozzle tip is provided. A mold having a slurry injection port communicating with the cavity, a porous mold disposed on the lower surface of the mold having the cavity and forming the joining surface, and the mold for forming the injection hole at the tip of the nozzle; A hole forming pin detachable from the mold and protruding into the cavity, a positioning table supporting the mold and supporting the porous mold positioned on the lower surface of the cavity, and a positioning table. A nozzle for the injection nozzle, comprising a molding pin which is removably disposed so as to protrude into the cavity and forms an inner surface of the nozzle tip. It relates molding apparatus end.

Since the method for forming the nozzle tip of the injection nozzle according to the present invention is configured as described above, in the state where shape retention is exhibited, shrinkage hardly occurs in the inlaid portion. Therefore, the hole forming pin can be extracted while maintaining the predetermined shape of the injection hole formed in the inlaid portion, and the hole shape is not broken. Therefore, it is possible to manufacture a small hole that requires precision and a hole having a complicated shape with high precision.

According to the method of forming the nozzle tip of the injection nozzle, for example, an injection nozzle having a polygonal hole shape and at least a nozzle tip made of a ceramic material can be easily manufactured.

In the method of molding the nozzle tip of the injection nozzle, the slurries having different components and constituent concentrations are sequentially injected into the cavity, for example, in the vicinity of the joining surface of the nozzle tip to the nozzle body. A structure having different types and composition ratios of constituent components between the portion and the other portion of the nozzle tip can be easily manufactured.

Furthermore, since the apparatus for forming a nozzle tip of an injection nozzle according to the present invention is configured as described above, the method for forming the nozzle tip of the injection nozzle can be easily implemented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the drawings, a description will be given of an embodiment of a method for forming a nozzle tip portion of an injection nozzle according to the present invention, an apparatus therefor, and an injection nozzle manufactured by the method. FIG. 1 is a schematic sectional view showing one embodiment of a nozzle tip forming apparatus of an injection nozzle according to the present invention, and FIG. 2 is an enlarged sectional view of a main part of FIG.

The injection tip forming apparatus of the injection nozzle is applied to manufacture a tip tip of a fuel injection nozzle used in a diesel engine, that is, a nozzle tip. As shown in FIGS. 1 and 2, a mold 1 is provided with a slurry injection port 2 and a cavity 3 communicating with the slurry injection port 2, and has a metal tip having a predetermined shape such as a polygon at the tip. A through hole 4 is formed for detachably attaching a pin removal jig 6 having a hole forming pin 5. The cavity 3 is formed in the lower surface 12 of the mold 1, and the slurry injection port 2 is formed in the cavity 3 from the upper surface of the mold 1.
Leads to. The shape of the cavity 3 has the outer shape of the tip of the fuel injection nozzle.

The mold 1 is set on a positioning table 8.
The upper surface 11 of the positioning table 8 is arranged in contact with the lower surface 12 of the mold 1. A hole 13 is formed in the positioning table 8, and a through hole 15 for raising and lowering the core 14 constituting the molding pin and the core elevating jig 10 to which the core 14 is attached is formed. . The core lifting jig 10 is detachably fixed to the positioning table 8 by an appropriate fixing means such as a screw, and functions as a molding pin that can protrude into the cavity 3.

In the hole 13 formed in the positioning table 8, a porous mold 9 made of gypsum or the like is arranged. The porous mold 9
It has an effect of absorbing water from the slurry S injected into the cavity 3 from the slurry injection port 2 to solidify the slurry inlaid portion 7. A through-hole 16 is formed in the porous mold 9 at a position facing the cavity 3, and the through-hole 16 is formed in the core 1.
4 is configured to be movable up and down. The core 14 is set so as to be able to rise up the through hole 16 and protrude into the cavity 3 formed in the mold 1. In some cases, a recess 18 may be formed on the outer surface of the core 14 so that the hole forming pin 5 is fitted into the recess 18.
Alternatively, the tip end surface of the hole forming pin 5 can be formed in a shape corresponding to the outer shape of the core 14. Alternatively, petroleum jelly or the like is applied to the surface of the core 14 so that the hole forming pin 5 is
Is set in a state where gaps are eliminated by contact with
Is injected into the cavity 3 from the slurry injection port 2, the forming hole can be formed accurately and accurately. The core 14 is set to protrude into the cavity 3, thereby forming the inner surface of the nozzle tip 22, that is, the sack portion of the fuel injection nozzle.

The molding device for the nozzle tip of the injection nozzle is configured as described above, and a ceramic member can be manufactured as follows. That is, the method of forming the nozzle tip portion of the injection nozzle includes a step of injecting the slurry S into the cavity 3 from the slurry injection port 2 formed in the upper part of the mold 1 in which the hole forming pin 5 is disposed, A step of allowing the porous mold 9 to absorb water, a step of extracting the hole-forming pin 5 from the inlaid part 7 with the inlaid part 7 exhibiting shape retention, and forming an injection hole 17 in the inlaid part 7, and a slurry. The process comprises a step of absorbing the moisture of S into the porous mold 9 to solidify the inlaid portion 7. The slurry S injected into the cavity 3 absorbs water by the porous mold 9 and forms an inking layer on the porous mold 9 and the core 14.

In this molding method, no shrinkage occurs in the inlaid layer in a state where an appropriate amount of water is absorbed from the inlaid layer and an appropriate amount of water remains in the inlaid layer. Receiving part 7
Although the shape-retaining property is developed, but the contraction does not occur in the inlaid layer, the hole forming pin 5 is pulled out from the inlaid section 7 so that the solid injection hole 17 is formed in the inlaid section 7. Can be formed. Further, before the inlaid portion 7 is completely solidified, the core 14, which is a sack portion forming pin, is lowered from the positioning table 8 and removed from the inlaid portion 7. Next, after the hole forming pin 5 and the core 14, that is, the forming pin are removed from the inlaid portion 7, water is completely absorbed from the inlaid portion 7 by the porous mold 9. Shrinkage occurs, but since the hole forming pin 5 has already been removed from the inlaid portion 7,
The inlaid portion 7 is not broken, and a molded body made of a ceramic material is formed. Further, the mold 1 is moved to the positioning table 8.
, And the molded body formed by the inlaid portion 7 is removed from the mold. The molded body becomes a sintered body by firing, and the tip of the fuel injection nozzle is manufactured.

In the method of forming the nozzle tip of the injection nozzle, a plurality of types of slurries S having different components and constituent concentrations are sequentially injected into the cavity 3 to produce a formed body as shown in FIG. 4, for example. be able to. That is, the compact can be formed into components having different components in the height direction according to the purpose, and by firing the compact, sintered bodies made of different ceramic materials can be manufactured. For example, when an injection nozzle is manufactured from this molded body, the nozzle tip portion 22 of the injection nozzle has a portion 21 near the joining surface with the nozzle body, a portion 20 adjacent to the portion 21 near the joining surface, and the portion 20. The tip portion 19 which is adjacent to and has the injection hole 17 is different in the type and composition ratio of the constituent components of the ceramic material. For example, the tip portion 19 is made of a heat-resistant and high-strength ceramic material, and the portion 21 near the joint surface with the metal nozzle body is made of a ceramic material having a composition rich in Al ₂ O ₃ and Y ₂ O _3. It can be manufactured and a metal-to-metal joint can be formed by the metal contained in the ceramic and the metal contained in the nozzle body, and the joining between the tip portion 19 and the metal nozzle body can be strengthened.

Next, a specific example of a method of forming the nozzle tip of the injection nozzle will be described. First, a ceramic powder of silicon nitride (Si ₃ N ₄ ), a sintering aid, a deflocculant,
A predetermined amount of polyvinyl alcohol was blended as water and an organic binder. Then, the mixture is mixed with a ball mill to obtain slurry S
I got The slurry S thus obtained was poured into the cavity 3 from the slurry injection port 2 formed in the mold 1 into a die for producing a nozzle tip of a fuel injection nozzle in the diesel engine shown in FIGS. Cavity 3
The slurry S injected into the cavity 3 absorbs water by the porous mold 9 and deposits in the cavity 3 to form a deposit layer. After a predetermined time has passed, the slurry S has a shape retaining property. Then, the hole forming pin 5 attached to the mold 1 is
The core 14, which is a molding pin attached to the positioning table 8, is extracted from the inlaid portion 7. In this state, the inlaid portion 7 is left in the mold, and the inlaid portion 7 is
, The water is further absorbed and discharged, and the inlaid part 7 is solidified. After the inlaid portion 7 was solidified to form a molded body of the ceramic member, the molded body was removed from the mold to obtain a molded body of the nozzle tip having the injection hole 17. The molded body of the nozzle tip is fired to produce a sintered body, and the sintered body is subjected to SEM (scan).
Observation with a ning electron microscope) confirmed that the shape of the injection hole and the like were extremely excellent.

In the method for forming the nozzle tip of the injection nozzle, as the ceramic powder, aluminum titanate, mullite, zirconia, potassium titanate or the like can be used in addition to silicon nitride. Further, as the organic binder, a thermoplastic acrylic resin capable of suppressing dimensional shrinkage in a process of manufacturing a ceramic member can be used in addition to polyvinyl alcohol.

Next, another embodiment of the apparatus for forming a ceramic member according to the present invention will be described with reference to FIG. FIG.
The molding apparatus shown in Fig. 1 is composed of the same parts as those shown in Fig. 1 except that the positioning table and the core are slightly different. Therefore, the same reference numerals are given to the components in the molding apparatus shown in FIG. 3 that are the same as the components shown in FIG. 1, and the duplicate description is omitted here. In FIG. 3, the positioning table 8 is supported by the lifting jig table 24, and the lifting jig 10 attached to the lifting jig table 24 is used.
The core 14 as a molding pin can be inserted into and removed from the cavity 3 by the operation of.

[0026]

The method for forming the nozzle tip of the injection nozzle according to the present invention is configured as described above, so that the injection hole formed in the inlaid portion forming the nozzle tip of the injection nozzle is formed by the method described above. The state in which the hole shape is maintained can be maintained, and a desired injection hole can be accurately and reliably formed. In particular,
Since the mold is located on the outer surface side of the nozzle tip, a compact having a small and complicated shape, that is, the nozzle tip of the injection nozzle can be manufactured with high precision. Since the porous mold is located on the surface side, a good joining surface to the nozzle body can be provided at the nozzle tip.

Furthermore, the method of forming the nozzle tip of the injection nozzle includes a step of sequentially injecting the slurries having compositions having different components and their constituent concentrations into the cavities to form inlaid portions having different compositions. It is possible to manufacture ceramic members made of materials with different compositions. For example, it is possible to easily manufacture injection nozzles with different types of components and composition ratios between the vicinity of the joint surface of the nozzle tip with the nozzle body and the other parts. Can be manufactured.

Also, a molding device at the nozzle tip of the injection nozzle has a mold having a slurry inlet and a cavity communicating with the slurry inlet, and is detachable from the mold and can project into the cavity. A hole forming pin, a positioning table supporting the mold, a porous mold disposed on the positioning table and positioned at the bottom of the cavity, and detachable from the positioning table and protruding into the cavity. Since there is a possible forming pin, the hole forming pin can be reliably and easily extracted from the molded product attached to the forming pin in the cavity.

According to this method of forming the nozzle tip of the injection nozzle, the shape of the injection hole formed at the nozzle tip of the injection nozzle is polygonal, and at least the nozzle tip is made of a ceramic material. A fuel injection nozzle with high heat resistance at the tip of the nozzle, and the injection hole itself can be easily formed into a square or other irregular shaped injection hole, and can be injected in a good spray pattern that can improve the combustion form it can.

According to the method for forming the nozzle tip of the injection nozzle, the injection nozzle is formed of a composition in which the types and composition ratios of the constituent components are different between the portion near the joint surface of the nozzle tip with the nozzle body and the other portion. Therefore, for example, the tip portion is made of a heat-resistant and high-strength ceramic material, and the portion near the joint surface with the metal nozzle body is Al ₂ O _3.
Or a material having a rich composition of Y ₂ O ₃ , a metal-to-metal bonding portion can be formed, and the bonding between the tip portion and the metal nozzle body can be strengthened.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a molding apparatus capable of achieving a method of molding a nozzle tip portion of an injection nozzle according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a schematic sectional view showing another embodiment of a molding apparatus capable of achieving a method of molding a nozzle tip portion of an injection nozzle according to the present invention.

FIG. 4 is a cross-sectional view showing an example of a molded body of a ceramic member manufactured by a method of molding a nozzle tip of an injection nozzle according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 2 Slurry injection port 3 Cavity 4 Through-hole 5 Hole forming pin 7 Filling part 8 Positioning stand 9 Porous mold 12 Lower surface 13 Hole 14 Core (forming pin) 17 Injection hole 19 Tip part 20 Tip part 21 Adjacent part of joining surface 22 Nozzle tip

Claims (5)

(57) [Claims] 1. A nozzle having an injection hole and joined to a nozzle body.
Forming method to form the nozzle tip with a joint surface
A key for forming the outer shape of the nozzle tip
A mold for forming the joint surface on a lower surface of a mold having a cavity.
A porous mold is arranged, and the injection hole is inserted into the cavity.
Forming hole forming pin and inner surface of nozzle tip
Step of in the molding pin disposed injecting slurry into the cavities, the step of water absorption of the water of the slurry into the porous mold, the slurry in the cavity adheres
Have been forming the injection hole in the inking unit withdrawn <br/> said hole forming pin from the inking unit in a state where shape retention to the inking unit is expressed, then the inking unit solidifying the inking unit by water moisture to the porous type, this consisting
A method for forming a nozzle tip of an injection nozzle . Wherein said slurry has a composition ingredients and its structure density different, the slurry of the different compositions are sequentially injected into said cavity, said <br/> inking unit of the different compositions are formed method of forming the nozzle tip of the injection nozzle according to <br/> claim 1, characterized in that that step contains Nde a which are Ru is. 3. A nozzle having an injection hole and joined to a nozzle body.
Forming device for forming a nozzle tip having a joining surface for
A key for forming the outer shape of the nozzle tip.
Cavity and a slurry inlet leading to the cavity
And a mold provided on the lower surface of the mold having the cavity.
A porous mold that is placed and forms the joining surface, the nozzle
Possible and hole molding pins can protrude into said cavity detachable from the mold to form the injection hole in the tip, the porous positioned the mold under surface of the support and the cavity positioning base you support the quality type, and can project removably to said cavity relative to said positioning mount
A nozzle for a spray nozzle, comprising a molding pin movably arranged and forming an inner surface of the nozzle tip.
Device at the tip of the tool. 4. The nozzle tip of the injection nozzle according to claim 1.
Manufactured by the molding method of the end , the nozzle tip
This shape of the formed the injection hole and at least the nozzle tip with polygon is made of a ceramic material
And an injection nozzle characterized by the following . 5. The nozzle tip of the injection nozzle according to claim 2.
Manufactured by the molding method of the end ,
Injection nozzle and said the portion near the joint surface of the nozzle tip, and the other parts of the nozzle tip of the kind and composition ratio of the components are composed of different materials.