JP2009255139A - Conical spring and apparatus for forming the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for forming a conical spring by which a highly accurate conical spring is obtained at high speed and at low cost by performing helical shearing work without having the slit width and forming of a spring in one process. <P>SOLUTION: In an apparatus 1 for forming a conical spring which is provided with a one-turn coil (formed coil) 5, a power source means for energizing the one-turn coil 5 and a die 2 provided with a forming part 2A, electromagnetic force is generated by making the current flow to the one-turn coil 5 from the power source means in the state where a sheet 3 is interposed between the one-turn coil 5 and the die 2 and the sheet 3 is pressed against the die 2 by the electromagnetic force, and the forming part 2A is made by forming a helical shape into a mortar shape on the die 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a forming apparatus for forming a conical spring from a thin plate using electromagnetic force and a conical spring formed thereby.

  An electromagnetic forming method has been proposed as a method for processing a metal plate. In this electromagnetic forming method, a large current is instantaneously applied to a forming coil to generate a shocking electromagnetic force. According to this method, molding with less distortion can be performed at high speed. This electromagnetic forming method is applied to, for example, caulking of pipes and shafts, overhang forming of a body portion, flange processing, etc., and has been used mainly for relatively thick aluminum materials having a plate thickness of about 1 mm to 2 mm. It was not widely used for forming thin plates.

  Therefore, the present applicant has previously proposed an electromagnetic forming apparatus for electromagnetically forming a thin plate (see Patent Document 1). This electromagnetic forming apparatus is configured so that at least the current concentration portion of the one-turn coil is planar, and the electromagnetic force generation region in the power concentration portion is both the mold forming portion and the restraining region around the forming portion. It is a thing. According to this electromagnetic forming apparatus, since the current concentrated portion of the one-turn coil has a flat shape, a uniform electromagnetic force is generated in the current concentrated portion, and since the coil is one-turn, the inductance is reduced and the coil has a period. A short damped oscillating current is generated. For this reason, a high induced current is generated, and as a result, the electromagnetic force is increased. The large electromagnetic force causes the thin plate to be uniformly pressed to the mold including the molding part of the mold and the periphery of the molding part. A high-quality molded product having a uniform groove depth can be obtained.

  The current-concentrated portion of the one-turn coil covers the molding part of the mold and a part of the peripheral part around it, and the electromagnetic force is applied to both the molding part of the mold and a part of the peripheral part of the periphery (restraint part). Since the part that contacts the constraining part around the molding part of the thin plate and the convex part of the mold is restrained by pressing strongly against the mold, the constraining part is drawn into the molding part side of the mold. Therefore, since the molding is performed only by the elongation of the thin plate of the molding portion, the generation of distortion is almost eliminated, the molded product is hardly warped, and a high-quality molded product with high flatness can be obtained.

  On the other hand, in Patent Document 2, as a method for forming a conical spring used in a keyboard such as an electric typewriter, a spiral cutting line having a predetermined number of turns by a cutting tool or etching on a thin plate body such as phosphor bronze. And the conical spring is raised and formed by raising the portion surrounded by the cut line, and according to this, the conical spring and the plate body on which the conical spring is mounted are integrally configured. be able to.

Moreover, in Patent Document 3, as an integrated manufacturing method of a large number of springs and the back plate thereof, a plurality of cuts of the same shape with a predetermined arrangement are formed in the annular spring material plate before quenching by press cutting, A method has been proposed in which the cut portion is raised by a press to form a protrusion, and then a spring material plate is quenched to make the protrusion or the whole spring.
JP 2007-296553 A Japanese Utility Model Publication No. 54-052587 JP 58-013424 A

  However, the methods proposed in Patent Documents 2 and 3 both require two steps, a shearing process for cutting and a forming process for forming a spring shape, and thus the problem is that man-hours increase and cost increases. is there.

  In addition, regarding the formation of a spiral cut (slit), a slit having a predetermined width can be processed by pressing or etching, but a slit having no width cannot be processed by pressing except in special cases. It is. In particular, Patent Document 3 discloses a method of forming a spiral cut by press cutting, but does not disclose a specific press working method. In addition, even if it is a spiral slit, when the width | variety is wide, it can process using a shear metal mold | die, but it is not realistic because of problems, such as durability of a metal mold | die.

  The present invention has been made in view of the above problems, and its object is to perform a spiral shearing process without a slit width and a spring forming in one step, so that a conical spring with high dimensional accuracy can be produced at high speed and low speed. It is an object of the present invention to provide a molding device that can be obtained at a low cost and a conical spring molded by the device.

  In order to achieve the above object, an invention according to claim 1 includes a molded coil, a power supply means for energizing the molded coil, and a mold including a molded part, and the molded coil and the mold As a molding apparatus for forming a conical spring by energizing the molding coil from the power supply means with a thin plate interposed therebetween to generate an electromagnetic force and pressing the thin plate against the mold by the electromagnetic force, It is characterized in that a molding part formed by forming a spiral shape in a mortar shape on a mold is formed.

  The invention according to claim 2 is characterized in that a plurality of spiral shapes are concentrically formed in the molding portion of the mold.

  A conical spring according to a third aspect of the present invention is formed by the molding device according to the first or second aspect.

  According to the present invention, when the forming coil of the forming apparatus is energized from the power supply means, the electromagnetic force generated in the forming coil acts as a forming force on the thin plate in the forming part of the mold, and the mortar-like step of the forming part At the same time, the thin plate is sheared along the spiral shape of the forming portion as a cutting edge, and at the same time, the portion of the thin plate sheared into the spiral shape is raised along the mortar-shaped forming portion and formed as a conical spring. Thus, spiral shearing without slit width and spring molding are simultaneously performed on a thin plate in one step to form a desired conical spring, and a conical spring with high dimensional accuracy can be formed at high speed and low cost by electromagnetic molding. Obtainable.

  In addition, when the thin plate is sheared in a spiral shape with a mortar-shaped step formed in the molding part of the mold, the material is sag in the sheared part of the thin plate. When compressed, adjacent shearing portions do not rub against each other, and the compressed conical spring forms a planar shape. And when using the conical spring formed in this way as an electrical contact such as a connector, when the conical spring expands and contracts, the central protrusion of the conical spring that becomes the contact rotates around the protrusion, Friction is generated between the protruding portion and the contact of the other party, and the contamination of the contact is removed by this friction by the self-cleaning function, and both the contacts are cleaned and the electrical connection between the contacts is made stable.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 is a cross-sectional view of the molding apparatus according to the present invention (cross-sectional view taken along line AA in FIG. 2), FIG. 2 is a plan view of the molding apparatus with a fixing member removed, and FIG. 3 is an exploded perspective view of the molding apparatus. 4 is a perspective view of the mold, FIG. 5 is a cross-sectional view taken along the line BB of FIG. 4, FIGS. 6A to 6C are partial cross-sectional views showing a forming process of the conical spring, and FIG. FIG.

  A forming apparatus 1 according to the present invention is an apparatus for forming a conical spring W shown in FIG. 7 using electromagnetic force, and is placed on a block-shaped mold 2 as shown in FIGS. A thin plate 3 as a molding material, a flat-plate driver 4 having a thickness of 0.5 mm made of aluminum which is a metal having higher conductivity than the thin plate 3, a one-turn coil 5 composed of an E-shaped metal flat plate, and a thickness The rectangular flat plate-shaped fixing members 6 having appropriate strength and rigidity that can withstand the reaction force that the one-turn coil 5 receives from the driver 4 are sequentially stacked, and the thin plate 3 and the driver 4 and between the driver 4 and the one-turn coil. 5, a heat-resistant sheet 8 made of polyimide and an insulating sheet 9 are interposed. These mold 2, thin plate 3, heat-resistant sheet 8, driver 4, insulating sheet 9, one-turn coil 5 and fixing member 6 are sequentially laminated, and the reaction force generated in the driver 4 by the electromagnetic force generated in the one-turn coil 5 To prevent the laminated structure from collapsing, it is fixed by vertical restraining means (not shown) (for example, between the ram and bolster of the press machine).

  By the way, as shown in FIGS. 4 and 5, a molding part 2A is formed at the center of the upper surface of the mold 2, and a flat peripheral part 2B is formed around the molding part 2A. Here, a spiral shape having the same shape as the conical spring W shown in FIG. 7 is formed in a mortar shape in the molded portion 2A. In the present embodiment, the maximum outer diameter of the spiral shape of the forming portion 2A is 21 mm, the spiral width is 3 mm, the step (downward pitch per round) is 1 mm, the number of turns is 3, and the maximum depth is 3 mm. Is set to In addition, a circular hole 2a having an inner diameter of 3 mm is formed at the center of the spiral shape of the molded part 2A to release air during molding, and the upper end periphery of the circular hole 2a prevents the material from rebounding during electromagnetic molding. For this purpose, a conical surface 2b having an angle of 45 ° is formed.

  As the material to be molded, the thin plate 3 is made of phosphor bronze (JIS C5191P) having a small conductivity and a thickness of 0.05 mm to 0.3 mm. As the thin plate 3, beryllium copper (JIS C1720P) having a thickness of 0.05 mm to 0.3 mm can be used.

  The driver 4 is made of aluminum (Al050) having a large conductivity and a thickness of 0.5 mm.

  The one-turn coil 5 is made of a chrome copper plate having a total length of about 270 mm and a thickness of 1.5 mm, and is formed in an E shape in plan view by the two slits 5a. A narrow current concentration portion 5A is formed at the center of the one-turn coil 5, and a wide return portion 5B is formed on the left and right sides of the slit 5a. Here, the length of the current concentration portion 5A of the one-turn coil 5 is set longer than the lengths of the mold 2, the thin plate 3, and the driver 4, and the width is set wider than the width of the molding portion 2A of the mold 2. ing. That is, as shown in FIG. 1, the current concentration part 5A of the one-turn coil 5 has a size that covers a part of the molding part 2A of the mold 2 and the surrounding peripheral part 2B from above.

  Further, as the heat-resistant sheet 8 and the insulating sheet 9, a 0.05 mm thick polyimide sheet having high electrical insulation and heat resistance is used. In the present embodiment, the same material is used for the heat-resistant sheet 8 and the insulating sheet 9, but another engineer plastic with high heat resistance can be used for the heat-resistant sheet 8.

  Incidentally, as shown in FIG. 2, a capacitor 11 as a power source is connected to the current concentrating portion 5A of the one-turn coil 5 and the return portions 5B on both sides thereof, and the current concentrating portion 5A of the capacitor 11 and the one-turn coil 5 is connected. The discharge gap switch 12 is connected in series between the two. Further, a DC high voltage power supply 10 is connected to the capacitor 11 in parallel. In the present embodiment, a DC high voltage power supply 10 having a rated voltage of 3000 V to 6000 V is used, and a capacitor 11 having a capacity of 400 μF is used. The capacitor 11 is charged in advance by the DC high voltage power supply 10. ing.

  Next, a method for forming the conical spring W shown in FIG. 7 by the forming apparatus 1 having the above configuration will be described.

  As shown in FIG. 1, a thin plate 3, a heat-resistant sheet 8, a driver 4, an insulating sheet 9, a one-turn coil 5, and a fixing member 6 are sequentially stacked on a mold 2 as a material to be molded. A state in which it is fixed so as not to collapse due to electromagnetic force generated in the one-turn coil 5, for example, the die 2 is fixed to the bolster of the press machine, and the fixing member 6 is fixed to the ram of the press machine, etc. When the discharge gap switch 12 shown in FIG. 2 is closed, the capacitor 11 that has been charged in advance is discharged from the capacitor 11 to the one-turn coil 5 in a time of about 10 μsec. In the one-turn coil 5, a current flows in the current concentrating portion 5A in the direction of the arrow in FIG. 2, and this current flows in the reverse direction in the left and right return portions 5B.

  Here, since the current concentrating portion 5A of the one-turn coil 5 has a thin planar shape with a thickness of 1.5 mm, its cross-sectional area is small, and since the coil is one-turn, the inductance is also small. For this reason, a large current flows through the current concentrating portion 5A in an impact, and a large magnetic field is instantaneously and uniformly generated in the current concentrating portion 5A. This magnetic field intersects the thin plate 3 and the driver 4. At this time, an eddy current is generated in the driver 4 having a high conductivity, and the eddy current and the magnetic field generated in the current concentrating portion 5A of the one-turn coil 5 are electromagnetically moved in the arrow direction (downward) in FIG. Force is generated. Since a heat-resistant sheet 8 and an insulating sheet 9 are interposed between the driver 4 and the thin plate 3, and between the one-turn coil 5 and the driver 4, respectively, a short circuit of current from the one-turn coil 5 to the driver 4, 4 and the thin plate 3 are reliably prevented from being welded by the insulating sheet 9 and the heat-resistant sheet 8, respectively, and a large eddy current is generated in the driver 4, and as a result, a large electromagnetic force is generated. As the material of the driver 4, a material having high conductivity such as copper, brass, gold, silver, etc. can be used in addition to aluminum.

  Further, the current concentrating portion 5A of the one-turn coil 5 has a thin planar shape, and the magnetic field generated therein is uniformly distributed in the region of the current concentrating portion 5A of the one-turn coil 5. Accordingly, the uniform magnetic field generated in the one-turn coil 5 and the electromagnetic force generated by the eddy current generated in the driver 4 are also uniform over the region of the current concentration portion 5A of the one-turn coil 5.

  Here, the eddy current (current density i) generated in the driver 4 and the electromagnetic force f working per unit area are given by the following equations.

roti = −κ (∂B / ∂t) (1)
f = i × B (2)
Where κ: driver (Al) conductivity
B: Magnetic flux density
t: Time When a large electromagnetic force is generated as described above, this electromagnetic force acts as a forming force on the thin plate 3 in the forming portion 2A of the mold 2, and the driver 4 applies the thin plate 3 to the mold 2. Press. Then, as shown in FIGS. 6A to 6C, the mortar-shaped step of the molding part 2A formed on the mold 2 becomes the cutting edge, and the thin plate 3 is successively continuous along the spiral shape of the molding part 2A. At the same time, the portion of the thin plate 3 that has been sheared into a spiral shape is raised along the mortar-shaped forming portion 2A to be formed as a conical spring W shown in FIG. In FIGS. 6A to 6C, the driver 4 is not shown.

  As described above, according to the molding apparatus 1 according to the present invention, the spiral spring without slit width and the spring molding are simultaneously performed on the thin plate 3 in one step to form the desired conical spring W. Therefore, a highly accurate conical spring W can be obtained at high speed and low cost by electromagnetic forming. Further, when the thin plate 3 is sheared into a spiral shape with a mortar-shaped step formed in the molding part 2A of the mold 2 as shown in FIGS. 6 (a) to 6 (c), Since the sagging of the material occurs in the shearing portion, the compressed conical spring W has a flat shape without being rubbed between adjacent shearing portions when the shaped conical spring W is compressed.

  By the way, the conical spring W formed by electromagnetic forming as described above can be used as an electrical contact of a connector or the like. However, when the conical spring W is used as an electrical contact, the conical spring W is expanded and contracted. Since the central projecting portion Wa of the conical spring W serving as a contact rotates about the projecting portion Wa, friction is generated between the projecting portion Wa and a contact (not shown) of the other party, and this friction causes contamination of the contact. Is removed by the self-cleaning function, both contacts are cleaned, and the electrical connection between the contacts is stabilized.

  In the above embodiment, a single spiral shape is formed in the molding portion 2A of the mold 2. However, by forming a plurality of winding shapes concentrically, a double spiral is formed as shown in FIG. A conical spring W ′ having a shape or a conical spring W ″ having a triple helical shape as shown in FIG. 9 can be formed.

  Next, still another embodiment of the present invention will be described with reference to FIGS.

  10 is a perspective view of a mold showing another embodiment of the present invention, FIG. 11 is a sectional view taken along the line CC of FIG. 10, and FIG. 12 is a perspective view of a conical spring according to another embodiment of the present invention. In FIG. 4, the same elements as those shown in FIGS. 4 to 7 are denoted by the same reference numerals, and the repetitive description thereof will be omitted below.

  When molding is performed using the mold 2 shown in FIGS. 4 and 5 in the embodiment, a conical spring W cut and raised from the thin plate 3 is obtained as shown in FIG.

  Also in the present embodiment, as shown in FIGS. 10 and 11, a spiral shape having the same shape as the conical spring W shown in FIG. 12 is formed in a mortar shape in the molding portion 2 </ b> A of the mold 2. In the present embodiment, the mortar-shaped spiral shape is made deeper than the spiral shape of the above-described embodiment so that a step of at least 1 mm is generated on the outer periphery of the spiral shape.

  Thus, when electromagnetic forming is performed using the mold 2 shown in FIG. 10 and FIG. 11, the thin plate is sheared at the outer periphery of the deep spiral shape formed in the forming portion 2 </ b> A of the mold 2. The conical spring W is independent from the thin plate as shown in FIG.

  In the above embodiment, the example in which one molding part 2A is formed on the mold 2 has been described. However, if a plurality of molding parts 2A are formed on the mold 2, a plurality of conical springs can be molded simultaneously. And productivity is increased. Further, if the molding apparatus according to the present invention is built in the progressive die, a large number of conical springs can be molded at high speed.

It is sectional drawing (AA sectional view taken on the line of FIG. 2) of the shaping | molding apparatus which concerns on this invention. It is a top view of the state which removed the fixing member of the shaping | molding apparatus which concerns on this invention. It is a disassembled perspective view of the shaping | molding apparatus which concerns on this invention. It is a perspective view of the metal mold | die of the shaping | molding apparatus which concerns on this invention. It is the BB sectional view taken on the line of FIG. (A)-(c) is a fragmentary sectional view which shows the formation process of a conical spring. It is a perspective view of the conical spring which concerns on this invention. It is a perspective view of the conical spring which concerns on another form of this invention. It is a perspective view of the conical spring which concerns on another form of this invention. It is a perspective view of the metal mold | die which shows another form of this invention. It is CC sectional view taken on the line of FIG. It is a perspective view of the conical spring which concerns on another form of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molding device 2 Mold 2A Mold molding part 2B Mold peripheral part 2a Mold circular hole 2b Mold conical surface 3 Thin plate 4 Driver 5 One-turn coil (molded coil)
5A One-turn coil current concentration part 5B One-turn coil return part 5a One-turn coil slit 6 Fixing member 8 Heat-resistant sheet 9 Insulating sheet 10 DC high-voltage power supply (power supply means)
11 Capacitor 12 Discharge gap switch W Conical spring Wa Conical spring protrusion

Claims (3)

A molding coil, a power supply means for energizing the molding coil, and a mold having a molding portion, and the molding from the power supply means with a thin plate interposed between the molding coil and the mold. A molding device that energizes a coil to generate electromagnetic force, and presses the thin plate against the mold by the electromagnetic force to form a conical spring,
An apparatus for forming a conical spring, wherein a forming portion is formed by forming a spiral shape in a mortar shape on the mold.   The conical spring molding apparatus according to claim 1, wherein a plurality of spiral shapes are formed concentrically in the molding portion of the mold.   A conical spring formed by the forming apparatus according to claim 1.

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