JP2002282982A - Method and device for manufacturing double tapered spring steel wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a double tapered spring steel wire in which tapered parts are provided at end parts of a straight part. SOLUTION: In manufacturing the double tapered spring steel wire in which the tapered parts are provided at both end parts of the straight part, the tapered parts are formed by a swaging machine or a peeling machine 16, the straight part and tapered parts are uniformly heated by induction heating and continuously hardened and tempered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring steel wire wound in, for example, a barrel-shaped or spindle-shaped coil spring shape, and a double-taper spring steel wire having a tapered tapered portion at both ends of a straight portion having a uniform cross section. And a method for producing the same.

[0002]

2. Description of the Related Art An ordinary coil spring is formed by winding a wire having the same diameter over its entire length. In the case of a barrel-shaped or spindle-shaped coil spring, as shown in FIG.
It is desirable to make the wire diameter of the coil small diameter portion 26 on the spring end side smaller than the wire diameter of No. 5. In this case, there is an advantage that a special spring characteristic can be obtained and the weight can be reduced as compared with a barrel-shaped spring having a strand having the same diameter as the whole length. For that purpose, it is desired to use a double-tapered steel wire having tapered tapered portions at both ends as a spring steel wire.

[0003] With regard to such a method of manufacturing a double tapered spring steel wire, the applicants have previously disclosed in Japanese Patent Laid-Open No.
There is a technique disclosed in Japanese Patent Application No. -169991 and proposed in Japanese Patent Application No. 2000-172440 for deformed steel wires. JP-A-11-169991 and Japanese Patent Application No.
The double-tapered steel wire described in 0-172440 relates to a method of forming with a rolling roll.

[0004]

However, such a method using a rolling roll is suitable for mass production of the same shape, but in the case of a small quantity of many kinds, the roll must be frequently changed when the dimensions are changed. There is a problem.

Therefore, in order to cope with the production of a small number of products of various types, forging is performed by a swaging machine for controlling the moving amount of the anvil in accordance with the feed of the wire, or the cutting blade is adjusted in accordance with the feed of the wire. There is a method of manufacturing a double taper wire by cutting and forming with a peeling machine that controls the position.

[0006] As described above, in the case of forming by a swaging machine or a peeling machine, conventionally, it was manufactured by two steps of a forming step and a step of performing quenching and tempering heat treatment by patenting or the like after forming. However, in order to shorten the process and reduce the number of steps, it is desirable that the forming process and the heat treatment process be performed in one process.

[0007] In order to prevent defects such as decarburization of the wire, heat treatment by induction heating is desirable. However, when the wire is induction-heated, if the steel wire has a uniform diameter, the entire length is uniformly heated, so continuous heat treatment is easy.However, a straight large-diameter portion and a tapered small-diameter portion in the length direction are required. When the double-tapered steel wire is continuously heated by induction heating, there is a problem that the temperature of the large-diameter portion is lower than that of the small-diameter portion, and the hardening hardness of the large-diameter portion is low and the tensile strength is not uniform.

Therefore, the present invention solves the above-mentioned problems, and mainly relates to a method of forming a double taper spring steel wire suitable for the production of a small number of various types of round steel wires, and a quenching and tempering heat treatment continuously with the steel wire. It is an object of the present invention to provide a manufacturing method and apparatus for obtaining a double tapered spring steel wire in which a large diameter portion and a small diameter portion have uniform hardness.

[0009]

In order to achieve the above object, a method of manufacturing a double-taper spring steel wire according to the present invention is directed to a double-taper spring steel wire having a straight portion having a uniform diameter and having tapered portions tapered at both ends of a straight portion. In production, the taper portion is forged by a swaging machine, or the taper portion is cut and formed by a peeling machine, and the steel wire to be processed is continuously quenched by induction heating, and the double taper forming and quenching heat treatment are continuously performed. It is characterized by performing.

[0010] At this time, the steel wire to be processed is tempered by induction heating continuously after quenching, and double taper forming and quenching are performed.
It is desirable to perform tempering heat treatment continuously.

That is, according to the above-described swaging machine or peeling machine, if the movement of the anvil and the cutting of the cutting tool are controlled with the progress of the wire, the wire can be formed into a taper. Since the amount of movement of the anvil or blade can be easily changed, double taper spring steel wires having different dimensions and shapes can be easily processed even in a small amount. The forging with a swaging machine may be performed by any of cold, hot or warm methods.

As described above, by continuously performing the forming and the heat treatment of the tapered portion, the processing time and the number of steps are reduced as compared with the conventional method of performing the taper forming and the quenching / tempering heat treatment in two steps. Cost is reduced.

In the quenching and / or tempering heating, the wire diameter of the steel wire to be processed is continuously detected, and the output of the heating means is controlled in accordance with the detected wire diameter value. It is desirable to heat the steel wire to a uniform temperature in the longitudinal direction to perform quenching and / or tempering heat treatment.

That is, the method of manufacturing a double-tapered steel wire according to the present invention does not heat the small diameter portion and the large diameter portion with the same electric power as in the prior art. Detecting the diameter, when heating a straight section with a uniform diameter, keep the output of the heating means constant and perform continuous heating.When heating the tapered section, decrease or increase the output of the heating means according to the diameter of the taper. By heating by heating, both the large-diameter straight portion and the tapered small-diameter portion are heated to a uniform temperature for heat treatment. As a result, it is possible to obtain a double-tapered spring steel wire in which both the straight portion and the tapered portion are uniformly heat-treated in hardness and tensile strength.

[0015] Alternatively, as a second method, in the quenching and / or tempering heating, the wire diameter of the steel wire to be processed is continuously detected, and the steel wire to be processed is detected in accordance with the detected wire diameter value. By controlling the feed rate through the heating means, the steel wire can be heated to a uniform temperature in the longitudinal direction and subjected to quenching and / or tempering heat treatment.

That is, in the first method, the straight portion and the tapered portion are heated to a uniform temperature by increasing or decreasing the output of the heating means in accordance with the wire diameter. The feeding speed of the wire passing through the heating means is slow when heating the large-diameter portion and fast when heating the small-diameter portion so as to make the temperature of the straight portion and the taper portion uniform.

In order to manufacture the above double taper spring steel wire, the manufacturing apparatus of the present invention comprises a swaging machine or a taper portion for forging a taper portion so that double taper forming and quenching heat treatment are continuously performed. A peeling machine for cutting and forming, a quenching heating means for heating a steel wire to be processed to a quenching temperature by induction heating, and a quenching cooling means for cooling and quenching after heating are arranged in series.

Further, after the quenching and cooling means, a tempering heating means for heating the steel wire to be processed to the tempering temperature by induction heating is provided so that the double taper forming and the quenching / tempering heat treatment are performed continuously. They are arranged in series.

Further, in the apparatus for manufacturing a double taper spring steel wire according to the present invention, in order to make the heating temperature of the straight portion and the taper portion uniform, the quenching or / and tempering heating means is provided with: Wire diameter detecting means for continuously detecting the wire diameter, and controlling the output of the heating means in accordance with the wire diameter value of the wire diameter detecting means so that the steel wire is heated to a predetermined temperature in the longitudinal direction. And control means for performing the control.

Alternatively, in order to make the heating temperature of the straight portion and the taper portion uniform, the quenching and / or tempering heating means and the wire diameter detecting means for continuously detecting the wire diameter of the steel wire to be processed are provided. Control means for controlling a feed rate at which the steel wire to be processed passes through the heating means in accordance with the wire diameter value of the wire diameter detecting means so that the steel wire is heated to a predetermined temperature in the length direction. It is characterized by having.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a conceptual diagram showing the overall configuration of a double taper spring steel wire manufacturing apparatus according to a first embodiment of the present invention, and FIG. 2 is a diagram showing an example of the shape of the double taper spring steel wire.

The double taper steel wire of the present invention embodiment, as shown in FIG. 2, at both ends of the straight portion 21 of the same diameter of the large diameter of the length L _2, the taper length L ₁₂ tapered portion 22 ,
23, and the other end of the tapered portions 22 and 23 has a length L.
_A continuous double tapered line connected by the small diameter straight portion 24 of FIG. By cutting this in the middle of the small diameter straight section 24, a single double tapered steel wire used for a spindle coil spring or the like is produced.

1, the payoff stand 1, the work feed detecting means 15, the taper forming means 16, the length measuring means 2, the first wire diameter measuring instrument 3, and the printing apparatus are arranged from the upstream side (right side in the figure). Heating coil (quenching heating means) 4,
A quenching water cooling jacket (quenching cooling means) 5, a second wire diameter measuring device 6, a tempering heating coil (tempering heating means) 7, a tempering water cooling jacket 8, and a winding stand 9 are arranged in tandem. As a result, the steel wire S (hereinafter referred to as “work”) unreeled from the payoff stand 1 is continuously tapered, quenched, and tempered, and wound around the winding stand 9.

As the taper forming means, a computer 1
A forging is performed by controlling the amount of the anvil going in and out according to the work feed amount detected by the work feed detecting means 15, and a forging is performed on the steel wire S. Is to be molded.

As a taper forming means, a cutting machine is controlled by a computer 17 so that the cutting blade is moved in and out, and the cutting amount is controlled in accordance with the work feed amount detected by the work feed detecting means 15 for cutting. Then, a predetermined tapered portion may be formed in the steel wire S.

The length measuring means 2 measures the moving length of the workpiece to be processed, based on the number of rotations of a roller rotating in contact with the surface of the workpiece.

The first wire diameter measuring device 3 and the second wire diameter measuring device 6
For example, a laser-type wire-diameter measuring device that continuously measures the wire diameter of a workpiece traveling with a non-contact measuring device is used.
The first wire diameter measuring device 3 and the second wire diameter measuring device 6 are respectively k ₁ from the center of the quenching heating coil 4 and the tempering heating coil 7.
It is disposed and the inlet side of the distance k _2.

Hardening heating coil 4 and tempering heating coil 7
Are connected so that power is supplied from the quenching high-frequency power supply 10 and the tempering high-frequency power supply 11, respectively. The quenching cooling jacket 5 and the tempering cooling jacket 8 are designed to rapidly cool the work heated by the quenching heating coil 4 and the tempering heating coil 7, respectively.

Although the details will be described later, the length measuring means 2 and the first
The quenching heating coil 4 and the tempering heating coil 7 are supplied from the quenching high-frequency power supply 10 and the tempering high-frequency power supply 11 by the measurement value signals of the wire diameter measuring device 3 and the second wire diameter measuring device 6, respectively.
Is controlled by a control device (control means) 12.

The production of a double tapered spring steel wire by the apparatus according to the first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, a work S previously drawn to the diameter of the large-diameter straight portion 21 shown in FIG. 2 is fed out of the payoff stand 1 and sent to a swaging machine (taper forming means) 16. The feed amount of the work S passing through the swaging machine (taper forming means) 16 is detected by the work feed detecting means 15.

First, the anvil position of the swaging machine (taper forming means) 16 is set by the computer 17 at a position corresponding to the diameter of the small-diameter straight portion 14 of the work S. As a result, when the work S is fed into the swaging machine (taper forming means) 16, the tip of the work S is forged to the diameter of the small-diameter straight portion 14, and the small-diameter straight portion 24 of the work S is formed. When a predetermined amount of feed by the workpiece feeding detection means 15 is detected, the anvil position of the swaging machine 16 is forged while opening in proportion to the feeding amount of the work S by a command of computer 17, the tapered portion of the length L ₁₂ 23 are formed. Tapered part 2
When 3 is molded, the length sent to the straight portion 1 of the work S in a state where the opening of the anvil position is stopped proceeds L ₂
1 is formed. In addition, in the straight part 21, the anvil may be advanced without touching the work, but the straight part 21 may be forged to a predetermined diameter.

The work S is detected by the work feed detecting means 15.
When There is detected that sent the length of L _2, anvil swaging machine proceeds forging while closing in proportion to the feeding amount of the work S again by a command from the computer 17, the tapered portion 23 opposite taper Is formed. When the workpiece S is fed length of L _12, forging closing of the anvil is stopped diameter straight portion 24 proceeds is molded. Further work S following the tapered portion 23 forged while moving in the direction to proceed to open again the anvil when L ₁ proceeds is molded. The same forging is continued, and the large-diameter and small-diameter straight portions 21 and 24 are alternately formed into the tapered portion 22,
A double tapered steel wire connected at 23 is produced.

In the above embodiment, the swaging machine is used as the taper forming means. However, a double taper line can be formed in the same manner by cutting using a peeling machine in which the position of the cutting bit is controlled by a computer. .

Next, the operation of heat-treating the double tapered wire formed as described above will be described. First, referring to the whole of FIG. 1, a work S taper-formed by a swaging machine (taper forming means) 16 is sent to a quenching heating coil 4 and is heated to a quenching temperature. Quenched and quenched. The quenched work S is continuously heated to a tempering temperature by a tempering heating coil 7, quenched and tempered by a tempering cooling jacket 8, and wound up on a winding stand 9. Thereby, the workpiece is continuously quenched and tempered.

More specifically, before the work S is introduced into the quenching and heating coil 4, the amount of movement is measured by the length measuring means 2 and its diameter is measured by the first wire diameter measuring device 3. You. The controller 12 is set in advance so that power corresponding to the diameter of the work measured by the first wire diameter measuring device 3 is input to the quenching heating coil 4.
That is, the control device 12 controls the quenching high-frequency power supply 10 to output to the quenching heating coil 4 electric power proportional to the square of the wire diameter in accordance with a change in the wire diameter of the work. In the present embodiment, the movement amount of the work is measured by the length
The position of the work measured by the wire diameter measuring device 3 is the distance k ₁
When it moves only and comes to the center position of the quenching heating coil 4,
It was set so that predetermined power was output to the quenching heating coil 4.

For example, the position of A of the diameter d ₁ of the small diameter portion of the work shown in FIG. 2 is measured by the first wire diameter measuring device 3, and the position of A is moved by the distance k _{1 and} the center of the quenching heating coil 10 is moved. power of P ₁ is output when it came to. And the work is B
Until moved to the position is heated at a constant power of P _1. The moving amount of the work is measured by the length measuring device 2.

When the work moves and the position B comes to the center of the quenching heating coil 10, the electric power is sequentially increased between the tapered portions B and C in accordance with the increase in the diameter of the taper, and this electric power is the square of the diameter. Is changed in proportion to. When the C position of the diameter d ₂ of the large-diameter portion comes to the center position of the quenching heating coil 4, the power of _{P 2 = P 1 × (d} 2 / d 1) 2 is output, C-D During this period, the work is heated by this constant power.

[0038] In yet a position of the workpiece is moved tapered portion D-E, sequentially power output amount to the opposite is being reduced to the power P ₁ at the position of E. As described above, by heating the quench heating coil 10 while changing the electric energy according to the diameter of the work, the large diameter portion, the tapered portion, and the small diameter portion of the double tapered wire are heated to the same temperature. The above control is performed by the control device 1
2 is performed.

The work heated by the quenching heating coil 4 is rapidly cooled and quenched by the quenching cooling jacket 5.
Here, since the entire length of the work is heated to a uniform temperature, the double tapered wire has uniform hardened hardness at both the large diameter portion, the tapered portion, and the small diameter portion.

Subsequently, the quenched work is continuously heated to the tempering temperature by the tempering heating coil 7 and tempered. The diameter of the work is measured by the second wire diameter measuring device 6 in the same manner as in the above-described quenching, and when this position comes to the center position of the tempering heating coil 7, a predetermined electric power proportional to the square of the wire diameter is applied to the tempering heating. Output to the coil 7. As in the case of quenching, the work is heated to a uniform temperature in the longitudinal direction, tempered, cooled by the tempering cooling jacket 8, and wound around the winding stand 9. The double tapered spring steel wire formed and heat-treated in this way has a uniform hardness and strength at both the large diameter portion and the tapered portion of the straight.

The double-tapered steel wire formed by the swaging machine 16 and continuously quenched and tempered is
It is cut at an intermediate position of 24 in FIG. 2 and is supplied to steel wires for coil springs one by one.

In the above embodiment, a swaging machine is used as the taper forming means. However, a double taper wire can be formed in the same manner by using a peeling machine in which the position of the cutting tool is controlled by a computer. The quenching and tempering can be continuously performed in the same manner as described above.

[Second Embodiment] In the first embodiment, the heating of the straight portion and the tapered portion of the double-tapered steel wire is performed by changing the output of the heating means while keeping the feed rate of the work constant during the heat treatment and heating. The temperature was made uniform.
In the second embodiment, the heating temperature of the straight portion and the tapered portion is made uniform by changing the feed rate of the work while keeping the output of the heating means constant in the heat treatment heating. FIG. 3 is a conceptual diagram showing the overall configuration of the double taper spring steel wire manufacturing apparatus according to the second embodiment.

In the second embodiment shown in FIG. 3, the arrangement of the payoff stand 1, the work feed detecting means 15, and the taper forming means 16 is the same as that of the first embodiment. Or a peeling machine is used.

Since the arrangement of the heat treatment means is similar to that of the first embodiment, the same parts will be described using the same symbols. The difference from the first embodiment is that the pinch rollers 18a and 18b are disposed between the swaging machine 16 of the taper forming means and the front of the quenching heating means 4, and the quenching heating means 4 and the tempering heating means 7 are provided. And pinch rollers 20a and 20b provided between the tempering heating means 7 and the front of the winding stand 9 so that the work passing through the quenching heating means 4 is pinched by the pinch rollers 19a and 19b. The workpieces driven by the tempering heating means 7 are driven by the pinch rollers 19b and 20b.
a. Thereby, the speed of the work passing through the quenching heating means 4 and the tempering heating means 7 is reduced by the swaging machine 16 and the winding roller 9.
It can be changed freely regardless of the speed.

Then, the pinch rollers 18b, 19a and 1
9b and 20a are controlled by the control device 12, respectively.
The speed at which the work passes through the quenching and heating means 4 and the tempering and heating means 7 is defined. The pinch rollers 18a and 20b at both ends are driven according to the speeds of the swaging machine 16 and the take-up stand 9, respectively.
It is to be absorbed by loops formed between a and 19b and between 20a and 20b.

Before the quenching and heating means 4, the first length measuring means 2
a and the wire diameter detecting means 3 are provided as in the first embodiment, but in the second embodiment, the tempering heating means 7 is provided.
Is also provided with a second length measuring device 2b and a wire diameter detecting means 6.

The control device 12 is set in advance so that predetermined constant power is applied to the quenching heating coil 4 and the tempering heating coil 7 from the quenching high-frequency power supply 10 and the tempering high-frequency power supply 11. .

The operation of the apparatus according to the second embodiment will be described below. Swaging machine (taper forming means)
The operation of No. 16 is the same as that of the first embodiment. The movement amount of the tapered workpiece is measured by the first length measuring means 2a, and the diameter thereof is also measured by the first wire diameter measuring device 3. It is.

The controller 12 drives the pinch rollers 18b and 19a to heat the large diameter portion and the small diameter portion to the same temperature in accordance with the diameter of the work measured by the first wire diameter measuring device 3. Is set in advance so as to control the feed speed of the work. That is, when the large-diameter portion is at the position of the quenching heating coil 4, the workpiece is sent slowly, and when the small-diameter portion is at that position, the work is sent earlier, so that the heating temperature of the large-diameter portion and the small-diameter portion is uniform. Is done. As described above, in the second embodiment, the heating temperature of the straight portion and the tapered portion is made uniform by changing the feed speed of the work while keeping the input of the heating means constant.

Subsequently, the quenched work is continuously heated to the tempering temperature by the tempering heating coil 7 and tempered. As in the case of the above-mentioned quenching,
The diameter is measured by the length measuring means 2a, and the diameter is measured by the second wire diameter measuring device 6. As in the case of quenching, the control device 12 drives the pinch rollers 19b and 20a to heat the large-diameter portion and the small-diameter portion to the same temperature in accordance with the diameter of the work measured by the second wire diameter measuring device 3. The feed rate of the work is controlled in such a manner as to be performed. The work heated to a uniform temperature in the longitudinal direction in the same manner as in the case of quenching is cooled by the tempering cooling jacket 8 and then wound around the winding stand 9 to complete the heat treatment.

That is, in the second embodiment, the work is moved at a constant speed by the swaging machine 16 and the winding stand 9, but the feed speeds of the quenching heating coil 4 and the tempering heating coil 7 vary. . This fluctuation is absorbed by the respective loops between the pinch rolls 18a and 18b, between 19a and 19b and between 20a and 20b.

As described above, according to the method and apparatus for manufacturing a double-taper spring steel wire of the present invention, since the tapered portion is formed by a swaging machine or a peeling machine, it is possible to cope with small-volume production to large-volume production. Conventionally, a taper forming process and a quenching and tempering heat treatment process are used.
In the present invention, the heat treatment of taper forming and quenching and tempering can be performed in one step.

Since the large diameter straight portion and the tapered portion are uniformly heated to the same temperature, a uniform coil spring can be obtained.

Further, since the steel wire is rapidly and quickly heated and quenched and tempered by induction heating or the like, defects such as decarburization do not occur unlike other heating methods.

[0056]

As described above, according to the present invention, various types of double-tapered spring steel wires which have been uniformly heat-treated with high strength can be easily obtained. And contributes to the improvement of the performance of the spring part, the cost of the double taper spring steel wire can be greatly reduced, and the applications of the barrel-shaped and spindle-shaped coil springs are greatly expanded.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an overall configuration of a double taper spring steel wire manufacturing apparatus according to a first embodiment of the present invention.

FIG. 2 is a view showing an example of a double-taper spring steel wire having a modified cross section according to the present invention.

FIG. 3 is a conceptual diagram showing an entire configuration of a double taper spring steel wire manufacturing apparatus according to a second embodiment of the present invention.

FIG. 4 is a view showing an example of the shape of a spindle-shaped coil spring.

[Explanation of symbols]

1 Payoff stand, 2 Length measuring means, 3 First wire diameter measuring device (Wire diameter detecting means), 4 Quenching heating coil (Quenching heating means), 5 Quenching water cooling jacket (Quenching cooling means), 6th 2 Wire diameter measuring device (wire diameter detecting means), 7 tempering heating coil (tempering heating means), 8 tempering water cooling jacket, 9 winding stand, 10 quenching high frequency power supply, 11
Tempering high-frequency power supply, 12 control device, 15 work feed detecting means, 16 taper forming means (swaging machine or peeling machine), 17 computer, 21 straight section, 22, 23 taper section, 24 cutting section, 2
5 coil body, 26 coil small diameter part, S work (steel wire)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B21F 35/00 B21F 35/00 A F term (Reference) 3J059 AD04 BA05 EA01 EA02 EA09 4E070 AB09 AC01 EA00 4E087 AA10 BA17 CA46 DB17 HA00 4K043 AA02 CA04 DA01 DA04 EA07 FA02 FA03 FA12 GA10

Claims (8)

[Claims] In the manufacture of a double-taper spring steel wire having tapered tapered portions at both ends of a straight portion having a uniform diameter, the tapered portion is forged by a swaging machine,
Alternatively, the taper portion is cut and formed by a peeling machine, the steel wire to be processed is continuously quenched by induction heating, and the double taper forming and quenching heat treatment are continuously performed to form a double tapered spring steel wire. Production method. 2. The double taper according to claim 1, wherein the steel wire to be processed is tempered by induction heating after the quenching, and double taper forming and quenching / tempering heat treatment are continuously performed. Manufacturing method of spring steel wire. 3. In the quenching and / or tempering heating,
By continuously detecting the wire diameter of the steel wire to be processed by the wire diameter detecting means and controlling the output of the heating means in accordance with the detected wire diameter value, the steel wire can be uniformly heated in the longitudinal direction. The method for producing a double-tapered steel wire according to claim 1 or 2, wherein quenching and / or tempering heat treatment is performed by heating the steel wire. 4. In the quenching and / or tempering heating,
By continuously detecting the wire diameter of the steel wire to be processed by the wire diameter detecting means and controlling the feed speed at which the steel wire to be processed passes through the heating means in accordance with the detected wire diameter value, The method for producing a double-tapered steel wire according to claim 1 or 2, wherein quenching and / or tempering heat treatment is performed by heating the steel wire to a uniform temperature in the length direction. 5. In a double taper spring steel wire manufacturing apparatus having a tapered portion tapered at both ends of a straight portion having a uniform diameter, the tapered portion is forged formed so that double taper forming and quenching heat treatment are continuously performed. A swaging machine or a peeling machine for cutting and forming a tapered portion, a quenching heating means for heating a steel wire to be processed to a quenching temperature by induction heating, and a quenching cooling means for cooling and quenching after heating are connected in series. An apparatus for manufacturing a double-taper spring steel wire, which is provided. 6. An apparatus for manufacturing a double tapered spring steel wire having tapered tapered portions at both ends of a straight portion having a uniform diameter so that double taper forming and quenching / tempering heat treatment are performed continuously. 6. The double-taper spring steel wire manufacturing apparatus according to claim 5, wherein tempering heating means for heating the steel wire to be processed to the tempering temperature by induction heating after the cooling-in means is arranged in series. 7. A quenching and / or tempering heating means, a wire diameter detecting means for continuously detecting a wire diameter of a steel wire to be processed, and the steel wire is heated to a predetermined temperature in a length direction. 7. The apparatus according to claim 5, further comprising control means for controlling an output of the heating means in accordance with a wire diameter value of the wire diameter detecting means. 8. A hardening or / and tempering heating means, a wire diameter detecting means for continuously detecting a wire diameter of a steel wire to be processed, and the steel wire is heated to a predetermined temperature in a length direction. 7. A double means according to claim 5, further comprising control means for controlling a feed speed at which the steel wire to be processed passes through the heating means in accordance with a wire diameter value of said wire diameter detecting means. Equipment for manufacturing tapered steel wire.