JP2001248498A - Method for manufacturing needle valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a high quality needle valve. SOLUTION: Plungers 2 exact in roundness can be manufactured as compared with manufacturing of a plurality of plungers 2 from a material by cutting by forming a plunger material s of one unit of the plungers 2 by molding a blank b by pressing and manufacturing the plungers 2 by cutting the plunger material s and the needle valve 1 can be manufactured to high quality. The plunger raw member s to be machined can be easily cut with high accuracy because the plunger raw member s is worked into a shape which can be easily cut by pressing molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a needle valve used for controlling fuel of a carburetor of an automobile or a general-purpose engine.

[0002]

2. Description of the Related Art As shown in FIG. 6, a carburetor of an automobile has a float for keeping a surface height h of fuel sent from a fuel tank (not shown) through a fuel passage 61 to a float chamber 62 constant. There is a lineage.

In this float system, the needle valve 1 provided on the float 63 opens and closes the fuel inlet in response to the rise and fall of the float 63 floating on the fuel surface in the float chamber 62 due to the increase and decrease of the fuel. , And always serves to keep the surface height h of the fuel constant.

A needle valve 1 used in such a float system is shown in FIG. The needle valve shown in FIG.
And a conical valve head 3 made of a conical elastic body, which is in contact with the fuel inlet at the front end thereof.

A conventional manufacturing process of the needle valve 1 will be described below.

[0006] First, a base material having a length of 5 to 8 m and provided with ribs 4 on the outer periphery is formed by pulling out a draw bench, and bending and twisting of the material are corrected by a stretcher. After that, the workpiece is cut into a length of 2 to 3 m, which can be machined by an automatic lathe of a spindle moving type, to obtain a long material 70.

[0007] The long material 70 is cut by a bar work by an automatic lathe of a movable spindle type, and a plurality of plungers 2 are manufactured from one long material.

[0008] As shown in FIG. 7, a guide bush 7 in which the outer periphery of a long material 70 is supported by a guide bush holder 74.
The guide bush 71 guides the long material 7
0 The long material 70 is gripped by the collet chuck 72 provided on the rear headstock, guided by the guide bush 71 and extruded in the direction of the arrow to guide the long material 70 by a predetermined length t as shown in FIG. Cutting is performed by exposing from the bush 71.

The predetermined length t of the long material 70 corresponds to one of the plungers 2, and the entire shape of one plunger 2 is formed by cutting here.
Separated from

When one plunger 2 is manufactured in this way, the long material 70 is extruded again by a predetermined length t.
A plurality of plungers 2 are manufactured from the long member 70 by performing cutting while exposing from the guide bush 71 and repeating the cutting. The plunger 2 to be manufactured is as shown in FIG.

Next, the plunger 2 manufactured as shown in FIG. 4 is placed in a molding die 40, and a cavity c provided at the tip of the plunger 2 is filled with an elastic molding material e to form a valve head 3
(A valve head forming step).

In this valve head forming step, a leak preventing portion 2a provided on the plunger 2 is in close contact with the mold 40 in order to prevent leakage of the elastic molding material e from the cavity c.

Thus, the needle valve 1 has been manufactured.

[0014]

However, the production of the above-mentioned prior art needle valve 1 has the following problems.

The shape of the rib 4 provided on the outer periphery of the elongated material 70 by pulling out the draw bench and the elongated material 70
In order to extrude the long material 70 by guiding the guide bush 71 when cutting with an automatic lathe of a movable spindle type, the outer diameter including the rib 4 is uneven.
Has to be adjusted to the maximum outer diameter of the long material 70.

When the guide inner diameter of the guide bush 71 is adjusted to the maximum outer diameter of the long material 70, a gap is formed between the guide inner diameter of the guide bush 71 and the outer diameter of the long material 70 at a portion smaller than the maximum outer diameter. Since cutting occurs, cutting is performed in a state where the center is displaced.

For this reason, when the plunger 2 is formed by cutting the conventional long material 70 with an automatic lathe of a movable spindle type, there is a problem that the roundness of the plunger 2 is poor due to the influence of the center runout.

In particular, if the roundness of the leakage preventing portion 2a of the plunger 2 is poor, the elastic molding material e leaks from the cavity c because it cannot be in close contact with the mold 40 and a gap is generated.

When the elastic molding material e leaks from the cavity c as described above, burrs are generated around the molded valve head 3 as shown in FIG.
Insufficient flow of the elastic molding material e (short shot) due to a decrease in the internal pressure causes molding failure, resulting in a deterioration in the quality of the needle valve 1.

On the other hand, if the guide inner diameter of the guide bush 71 is made smaller than the maximum outer diameter of the long material 70 in order to prevent the center run-out, the guide material is pushed out of the guide bush 71 when the guide material is pushed out. The portion of the long material 70 having a diameter larger than the inner diameter is rubbed against the inner diameter of the guide and seized by frictional heat, so that cutting cannot be performed.

Further, cutting a plurality of plungers 2 one by one from the long material 70 causes the long material 70 to bend or twist under the influence of vibrations or the like at the time of cutting. The plunger 2 manufactured by cutting the twisted long material 70 may have poor dimensional accuracy.

Even in the case of the plunger 2 having poor dimensional accuracy manufactured from the long material 70 having a bend or twist, the leakage preventing portion 2a of the plunger 2 cannot be in close contact with the molding die 40 in the valve head forming step, and a gap is generated. As a result, the elastic molding material e leaks from the cavity c, and as a result, the quality of the needle valve 1 is reduced.

As shown in FIG. 3, the plunger 2 may be provided with a hole 5 which is open at the rear end face, or may not have the hole 5. When there is a hole 5 as shown in FIG. 3 (a), if this hole 5 is formed by cutting, depending on the cutting conditions, the cut scum adheres to the cutting edge of a cutting tool (drill, reamer) and the formed cutting edge. May occur.

[0024] If a component edge is formed, there arises a problem that the diameter of the hole 5 becomes larger as it goes deeper. Since the residue generated from the cutting edge is removed from the cutting edge when the cutting tool is pulled out from the hole 5, the diameter of the opening of the hole 5 is normal, and it is difficult to find this defect.

Further, since chips when cutting are left in the hole 5, the chips in the hole 5 need to be removed by sorting all the chips.

As described above, by forming the hole 5 in the plunger 2 by cutting, the quality of the needle valve 1 is deteriorated.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method of manufacturing a high-quality needle valve.

[0028]

According to the present invention, there is provided a needle valve having a plunger and a valve head formed of an elastic material at a tip end of the plunger. Wherein a blank is formed by forging to form a plunger material for each plunger, and the plunger material is cut to produce the plunger.

Therefore, according to the present invention, a plurality of plungers are cut from a single material to manufacture a plunger by cutting the plunger material for each plunger formed by forging. In comparison, a plunger that is accurate to a roundness can be manufactured, and a needle valve can be manufactured with high quality.

Further, since the plunger material to be cut is processed into a shape that can be easily cut by forging, the plunger material can be cut easily and with high precision.

When the plunger is manufactured with a roundness, the plunger can be arranged in the molding die as set when the valve head is molded into the plunger, so that leakage of the elastic molding material from the cavity can be prevented. In addition, no burr is generated around the formed valve head, and no molding failure is caused by a flow failure (short shot) of the elastic molding material due to a decrease in the internal pressure inside the cavity.

The plunger material is preferably formed by forging a portion to be gripped by a chuck when cutting the plunger material and a rib protruding from the outer periphery of the plunger.

Thus, the plunger material can be cut accurately by gripping the gripped portion with the chuck, and the ribs can be formed into a uniform shape by forging.

The plunger material is preferably formed by forging a hole opening at the rear end face of the plunger.

As a result, it is possible to manufacture a hole having a dimensional accuracy more accurate than a case where the hole is formed by cutting.
Needle valves can be manufactured with high quality.

For this reason, it is possible to solve the problem that the diameter of the hole becomes larger as it goes deeper in the case where the hole is formed in the plunger by cutting the hole, and that chips generated when the hole is cut remain in the hole. .

[0037]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

Here, the structure, shape, and application location of the needle valve 1 are the same as in the prior art, and thus description thereof is omitted. In the present embodiment, a method of manufacturing the needle valve 1 will be described.

In the method of manufacturing the needle valve 1 according to the present embodiment, the plunger 2 is manufactured by a forging process for forming the plunger material s and a cutting process for forming the plunger 2 from the plunger material s, and the plunger 2 is formed. The valve head 3 is provided in a valve head forming step of forming the valve head 3 by arranging it on the mold 40.

First, an example of the head forming process for forming the plunger material s will be described with reference to FIG. FIG. 1 is an explanatory diagram showing a pressure forming process for forming the plunger material s according to the embodiment.

A blank b having a predetermined shape is formed by cutting the round coil material (FIG. 1A). The blank b having the predetermined shape can form a plunger material s for each plunger 2 required to manufacture one plunger 2.

Then, on one end side of the blank b, a gripped portion 11 where the plunger material s is gripped by the chuck 20 at the time of cutting is forged (FIG. 1B), and the other end side of the blank (with the plunger portion 12). Hole) 5 from the end surface of the plunger 12 (see FIG. 1C).
Is forged (FIG. 1D).

The plunger material s shown in FIG. 1D is obtained by forging the gripped portion 11, the hole 5, and the rib 4 described above. The plunger material s is 1 plunger 2
It is for cutting and manufacturing in units of individual pieces, for example, the length of the gripped portion 11 is about 5 to 8 mm, the length of the plunger section 12 is about 7 to 15 mm, and the depth of the hole 5 is about 6 to 14 mm. Is provided.

The hole 5 is provided when necessary for the plunger 2, and is omitted when unnecessary.

Next, a cutting process for forming the plunger 2 from the plunger material s will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a cutting step of forming the plunger 2 from the plunger material s according to the embodiment.

The gripped portion 11 of the plunger material s is gripped by the chuck 20 (FIG. 2A), cut into a plunger shape by a part work by an automatic lathe of a fixed spindle type, and the plunger 2 is removed from one plunger material s. It is manufactured individually (FIG. 2 (b)). The plunger 2 to be manufactured is as shown in FIG.

In this cutting step, a leakage preventing portion 2a is provided which is in close contact with the molding die 40 during the valve head molding step to prevent leakage of the elastic molding material e from the cavity c. The shape of the leakage prevention portion 2a includes, for example, a tapered shape, a chamfered shape, a shape without a chamfered shape, and the like, and any shape requires a highly accurate roundness.

Then, as in the prior art, as shown in FIG. 4, the valve head 3 is formed at the tip of the plunger 2 in a valve head forming step. The plunger 2 is placed in a molding die 40, and a cavity c provided at the tip of the plunger 2 is filled with an elastic molding material e to form the valve head 3.

Here, the leakage preventing portion 2a provided on the plunger 2 is in close contact with the molding die 40, so that the elastic molding material e does not leak from the cavity c.

The plunger 2 shown in FIG.
And a needle valve 1 having a plunger 2 and a valve head 3 at a tip end thereof.

In the present embodiment described above, the plunger 2 is manufactured by cutting the plunger material s after forming the plunger material s in units of the plunger 2 by forging, as in the prior art. Compared to cutting and manufacturing a plurality of plungers 2 from one long material, it is possible to manufacture the plunger 2 with accurate dimensional accuracy.

According to the prior art, when a plurality of plungers 2 are cut from one long material and manufactured, the roundness of the plungers 2 becomes poor due to the influence of the core run-out, or the vibrations during cutting. Since the plunger 2 is manufactured from a long material that has been bent or twisted under the influence of, for example, the dimensional accuracy of the plunger 2 is poor. In the present embodiment, however, one plunger material s is used for one plunger material s. This is because the plunger 2 is only cut, and the material is not affected by the cutting.

Further, since the plunger material s to be cut is formed by processing the blank b into a shape that can be easily cut by forging, cutting can be performed easily and with high precision.

When the plunger 2 is manufactured to be accurate to the roundness, the plunger 2 can be arranged on the molding die 40 as set when the valve head 3 is molded on the plunger 2, so that the leak preventing portion 2a of the plunger 2 is provided. Can be prevented from leaking from the cavity c due to the close contact with the molding die 40.

As a result, burrs are not generated around the formed valve head 3, and a molding failure is caused by a flow failure (short shot) of the elastic molding material e due to a decrease in the internal pressure inside the cavity c. Therefore, the needle valve 1 can be manufactured with high quality.

On the other hand, in the plunger material s, the gripped portion 1 to be gripped by the chuck 20 when cutting the plunger material s.
1 and the ribs 4 protruding from the outer periphery of the plunger 2 are forged, so that the plunger material s can be cut accurately by gripping the gripped portion 11 with the chuck 20.
Further, the ribs 4 can be formed into a uniform shape by forging.

Further, a hole 5 opening to the rear end face of the plunger 2 is formed by forging in the plunger material s.
Compared to the case where the hole 5 is provided by cutting, the hole 5 with accurate dimensional accuracy can be manufactured.

For this reason, when the hole 5 is formed by cutting the plunger 2, the diameter of the hole 5 becomes larger as it goes deeper, and chips generated when the hole 5 is cut remain in the hole 5. That can be resolved.

[0059]

As described above, according to the present invention, a plurality of plungers are cut from one material by manufacturing a plunger by cutting a plunger material for each plunger formed by forging. It is possible to manufacture a plunger that is accurate to the roundness, compared to manufacturing with
Needle valves can be manufactured with high quality.

Since the plunger material to be cut is processed into a shape that can be easily cut by forging, the plunger material can be cut easily and with high precision.

In the plunger material, a gripped portion gripped by the chuck when cutting the plunger material and a rib protruding from the outer periphery of the plunger are formed by forging, so that the cutting of the plunger material is performed by the chuck. And the ribs can be formed accurately by pressing and forging.

A hole that opens to the rear end face of the plunger is formed by forging in the plunger material, so that a hole with a more accurate dimensional accuracy can be manufactured as compared with a case where the hole is cut and provided. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a pressure forming process for forming a plunger material according to an embodiment.

FIG. 2 is an explanatory view showing a cutting step of forming a plunger from a plunger material according to the embodiment.

FIG. 3 is a configuration diagram showing a plunger.

FIG. 4 is an explanatory view showing a valve head forming step of forming a valve head at the tip of the plunger.

FIG. 5 is a configuration diagram showing a needle valve.

FIG. 6 is a schematic configuration diagram showing the vicinity of a float system of a carburetor of an automobile to which a needle valve is applied.

FIG. 7 is an explanatory view showing a cutting step of forming a plunger from a long material of the related art.

FIG. 8 is an explanatory view showing a cutting step of forming a plunger from a long material of the related art.

FIG. 9 is a view showing a state in which burrs are generated in the valve head forming of a conventional needle valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Needle valve 2 Plunger 2a Leak prevention part 3 Valve head 4 Rib 5 Hole part 11 Grasped part 12 Plunger part 20 Chuck 40 Mold 61 Fuel passage 62 Float chamber 63 Float

Claims (3)

[Claims] 1. A method of manufacturing a needle valve, comprising: a plunger; and a valve head formed of an elastic body at a tip end of the plunger. And manufacturing the plunger by cutting the plunger material. 2. The plunger blank is formed by forging a gripped portion to be gripped by a chuck when cutting the plunger blank and a rib protruding from an outer periphery of the plunger. 3. The method for manufacturing a needle valve according to item 1. 3. The method for manufacturing a needle valve according to claim 2, wherein a hole opening at a rear end surface of the plunger is formed in the plunger material by forging.