JP2014210958A - Method of producing flat spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique allowing heat treatment of a flat spring in a short time.SOLUTION: A method of producing a flat spring includes a clamp step of clamping a spring material W formed in a specified shape with a pair of electrodes (16a, 16b) and (18a, 18b) arranged at an interval in the longitudinal direction of the spring material W and an electrification heating step of electrifying the spring material W through the pair of electrodes (16a, 16b) and (18a, 18b) to heat the spring material W.

Description

  The present specification discloses a manufacturing technique of a leaf spring (for example, a leaf spring used in a leaf type suspension installed in an automobile or the like).

  When manufacturing a leaf | plate spring, various heat processing is performed (nonpatent literature 1). For example, heating before tempering, tempering, heat treatment performed before painting the surface of the spring material, and the like can be mentioned. For such heat treatment, a heating furnace such as a hot air furnace or an infrared heating furnace is usually used. When heat treatment is performed using a heating furnace, a spring material formed into a product shape is put into the heating furnace from one end of the heating furnace. The spring material put into the heating furnace is heated while being conveyed toward the other end of the heating furnace, and is carried out of the heating furnace from the other end of the heating furnace. Thereby, the spring material is subjected to heat treatment.

The Spring Society of Japan "Spring" 4th edition, pages 498-508, Maruzen Co., Ltd.

  In the prior art, since the leaf spring is heat-treated in a heating furnace, it takes time for the heat treatment and productivity is lowered. Further, since the spring material is heated while being conveyed, if the heating time is increased, the heating furnace is enlarged accordingly. As the heating furnace becomes larger, energy efficiency also decreases.

  This specification aims at providing the technique which can perform the heat processing implemented to a leaf | plate spring in a short time.

  A method of manufacturing a leaf spring disclosed in the present specification includes a clamping step of clamping a spring material formed into a predetermined shape with a pair of electrodes spaced apart in the longitudinal direction of the spring material, and a pair of electrodes. An energization heating step of heating the spring material by passing an electric current through the spring material.

  In this manufacturing method, the spring material is heated by passing an electric current through the spring material. That is, the spring material is heated by energization heating. Since current heating can heat the spring material in a short time, the time required for the heat treatment can be shortened.

The figure which shows typically the whole structure of the heat processing equipment which heat-processes a leaf spring. The figure which shows typically the structure of the electric heating apparatus which energizes and heats a leaf spring. The figure which expands and shows the site | part clamped with an electrode which is an edge part of a leaf spring. The figure which shows typically the structure of the induction heating apparatus which carries out the induction heating of the edge part of a leaf spring. The figure which shows an example of the state of a leaf spring and an induction coil when the edge part of a leaf spring is induction-heated. The figure which shows the leaf spring which concerns on an Example. The figure which expands and shows the other example of the site | part clamped with an electrode which is an edge part of a leaf spring.

  The main features of the embodiments described below are listed. The technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Absent.

(Characteristic 1) In the manufacturing method disclosed in this specification, the pair of electrodes may clamp both ends of a spring material formed in a predetermined shape. According to such a structure, an electric current flows between the both ends of a spring material, and the whole spring material can be heated.

(Feature 2) The manufacturing method disclosed in the present specification may further include an induction heating step of heating both ends of the spring material by induction heating. According to such a structure, the part clamped with the electrode and / or the part outside the part clamped with the electrode can be heated, and the whole spring material can be heated without leakage.

  A manufacturing method according to the example will be described. In this embodiment, an example of manufacturing a leaf spring which is a kind of leaf spring will be described. First, the leaf spring will be briefly described. Leaf springs are used in leaf suspensions installed in automobiles and the like. As shown in FIG. 6, the leaf spring W is a plate-like spring, and is curved so as to protrude toward the one surface 42 (the upper surface in FIG. 6). That is, one surface 42 (upper surface in FIG. 6) of the leaf spring W is a convex surface, and the other surface 44 (lower surface in FIG. 6) is a concave surface. Eyeballs 40 are formed at both ends of the leaf spring W. When the leaf spring W is mounted on the automobile, a support shaft (bibot or shackle) on the vehicle body side is attached to the eyeball 40. When the leaf spring W is attached to the vehicle body, a force acts on the leaf spring W in the direction of the arrow 46. As a result, compressive stress acts on one surface 42 of the leaf spring W, and tensile stress acts on the other surface 44.

  In order to manufacture the leaf spring W described above, first, spring steel (for example, SUP6, SUP9, SUP9A, SUP11A, etc.) is processed into a plate material of a predetermined size, and machine processing (for example, drilling, rolling, etc.) is performed on the plate material. ) To make a semi-finished product shape. Next, the plate material in a semi-finished product shape is heated to form a curved shape, and then quenched. Next, after tempering the plate material after quenching, surface treatment such as shot peening is performed. Thereafter, heating is performed until the surface temperature reaches a predetermined coating temperature, and paint is sprayed on the heated surface for coating. Thereby, the leaf spring W is manufactured. In the present embodiment, the heat treatment according to the present invention is performed in the quenching process, the tempering process, and the heating process before painting performed on the semi-finished plate material. In addition, since it can carry out similarly to a conventionally well-known method about parts other than heat processing, the detailed description is abbreviate | omitted here.

  First, a heat treatment facility for heat-treating a semi-finished plate material (hereinafter sometimes simply referred to as a plate material W) will be described. As shown in FIG. 1, the heat treatment facility includes an energization heating device 10 that energizes and heats the plate material W and an induction heating device 30 that induction-heats the plate material W. As will be described later in detail, the plate member W is first heated at the central portion except the end by the electric heating device 10, and then the end is heated by the induction heating device 30.

  As shown in FIG. 2, the energization heating apparatus 10 includes a power source 12, electrodes 16a and 16b connected to the power source 12 through the switch 14 and the wiring 20a, and electrodes 18a connected to the power source 12 through the wiring 20b. , 18b. As the power source 12, either a DC power source or an AC power source can be used. The on / off state of the switch 14 is controlled by a control device (not shown).

  The electrodes 16a and 16b clamp one end of the plate material W, and the electrodes 18a and 18b clamp the other end of the plate material W. When the pair of electrodes (16a, 16b), (18a, 18b) clamps the plate material W, the electrodes (16a, 16b), (18a, 18b) and the plate material W are in electrical contact. Thus, one electric circuit is formed by the power source 12, the wirings 20a and 20b, the switch 14, the electrodes (16a and 16b) and (18a and 18b), and the plate material W. For this reason, when the control device turns on the switch 14, a current flows through the plate material W, and the plate material W is energized and heated. When the control device turns off the switch 14, the current flowing through the plate material W is cut off.

  Here, the positions where the electrodes (16a, 16b), (18a, 18b) clamp the plate material W clamp the position from the center of the end of the plate material W rather than the centerpiece 40. That is, as shown in FIG. 3, the center position C <b> 1 is clamped rather than the centerpiece 40. For this reason, when the plate material W is energized and heated, a current flows from the clamped position C1 to a portion from the center, and the portion where the current flows is heated. Therefore, the eyeball 40 outside the clamped position C1 is not heated. The electrodes (16a, 16b) and (18a, 18b) clamp the side surfaces of the plate material W. Unlike the surfaces 42 and 44 of the plate material W, the side surface of the plate material W is not curved. For this reason, when the side surface of the plate material W is clamped by the electrodes (16a, 16b), (18a, 18b), the clamp surfaces of the electrodes (16a, 16b), (18a, 18b) (surfaces in contact with the plate material W) Can be a flat surface.

  As shown in FIG. 4, the induction heating device 30 includes two AC power sources 32a and 32b, and heating coils 36a and 36b connected to the AC power sources 32a and 32b via wirings 34a and 34b. The on / off of the AC power supplies 32a and 32b is controlled by a control device (not shown).

  The heating coils 36a, 36b are cylindrical coils in which windings are wound in a spiral shape, and are formed in such a size that the end portion (that is, the eyeball 40) of the plate material W can be disposed inside (inner side). Yes. The winding of the heating coil 36a is connected to the AC power source 32a via the wiring 34a. For this reason, when the AC power supply 32a is turned on, an AC current flows through the heating coil 36a. Similarly, the winding of the heating coil 36b is connected to the AC power supply 32b via the wiring 34b. When the AC power supply 32b is turned on, an AC current flows through the heating coil 36b.

  When the plate material W is heated by the heat treatment equipment described above, first, the plate material W is energized and heated by the energization heating device 10. Specifically, one end of the plate material W (specifically, the position of C1 in FIG. 4) is clamped by the electrodes 16a and 16b, and the other end of the plate material W is clamped by the electrodes 18a and 18b. Next, the switch 14 is turned on and the power supply 12 is turned on to pass a current through the plate material W. When an electric current flows through the plate material W, the entire portion excluding the end portions of the plate material W (portions outside the electrodes 16a, 16b, 18a, and 18b (that is, the eyeball 40 and its vicinity)) is heated. When the plate material W rises to a predetermined temperature, the switch 14 is turned off, and the energization heating to the plate material W is finished.

  When the energization heating to the plate material W is completed, the plate material W is conveyed to the induction heating device 30. When the plate material W is conveyed to the induction heating device 30, the heating coil 36 a is arranged at one end of the plate material W, and the heating coil 36 b is arranged at the other end of the plate material W. Specifically, the heating coil 36a is arranged with respect to the plate material W such that one end of the plate material W (a portion outside the portion clamped by the electrodes 16a and 16b) is positioned inside the heating coil 36a. At the same time, the heating coil 36b is disposed with respect to the plate material W so that the other end of the plate material W (the portion outside the portion clamped by the electrodes 18a and 18b) is positioned inside the heating coil 36b. When the heating coils 36a and 36b are set with respect to the plate material W, the AC power sources 32a and 32b are turned on, and an alternating current is passed through the heating coils 36a and 36b. Thereby, an eddy current is generated at both ends of the plate material W, and both ends of the plate material W are heated by the eddy current. Inside the heating coils 36a and 36b, a portion that is not heated by the energization heating device 10 is located, and this portion is heated by induction heating. As a result, the entire plate material W is heated and necessary heat treatment is performed.

  As described above, in the manufacturing method of the leaf spring W of the present embodiment, the leaf spring W is heat-treated using the energizing heating device 10 and the induction heating device 30. For this reason, the leaf spring W can be heated in a short time, and the time required for the heat treatment can be shortened. Moreover, since the site | part which could not be heated with the electric heating apparatus 10 is heated with the induction heating apparatus 30, the whole leaf spring W can be heat-processed without a leak. In particular, in the induction heating device 30, the heating coils 36 a and 36 b and the leaf spring W do not come into contact with each other, so that there is no problem that the portion in contact with the electrode is difficult to heat unlike the energization heating device.

  As mentioned above, although the specific example of the technique disclosed by this specification was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  For example, in the above-described embodiment, the leaf spring W is heat-treated using the electric heating device 10 and the induction heating device 30, but the leaf spring W may be heat-treated using only the electric heating device 10. For example, as shown in FIG. 3, the tip C2 of the side surface of the leaf spring W (that is, the tip of the eyeball 40) is clamped by the electrodes 16a, 16b, 18a, and 18b so that a current flows through the entire leaf spring W. Also good. By clamping the tip C2 of the leaf spring W with an electrode, the leaf spring W can be heat-treated only by energization heating. Alternatively, as shown in FIG. 7, the tips of one surface (convex surface) and the other surface (concave surface) of the leaf spring W may be clamped by electrodes 48a and 48b. Even with such a configuration, a current flows through the entire leaf spring W, and the leaf spring W can be heat-treated only by energization heating.

  In the above-described embodiment, the vicinity of the eyeball 40 of the leaf spring W is clamped by the electrodes 16a, 16b, 18a, and 18b. However, the portion to be clamped by the electrodes 16a, 16b, 18a, and 18b is limited to such an example. I can't. For example, when the leaf spring W has a central portion where the cross-sectional area is uniform and both end portions where the cross-sectional area changes, the central portion where the cross-sectional area is uniform is heated by energization heating, and both end portions where the cross-sectional area changes May be heated by induction heating. According to such a configuration, the entire leaf spring W can be heated uniformly.

  Further, in the above-described embodiment, the heating coils 36a and 36b are arranged on the outer peripheral side of the end portion of the leaf spring W, but the induction heating method is not limited to such a method. For example, as shown in FIG. 5, a coil spring 38 may be disposed inside the centerpiece 40 of the leaf spring W. By disposing the coil spring 38 inside the centerpiece 40 of the leaf spring W, the surface 44 side of the leaf spring W (that is, the surface on which tensile stress is generated) can be further heated. As a result, it is possible to appropriately manage the heat treatment quality on the side where the mechanical strength is required. The end of the leaf spring W may be heated by arranging heating coils on both the inside and outside of the centerpiece 40. By heating the eyeball 40 of the leaf spring W from both sides (inside and outside), the end of the leaf spring W can be sufficiently heated.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

DESCRIPTION OF SYMBOLS 10 Current heating apparatus 12 AC power supply 14 Switch 16a, 16b, 18a, 18b Electrode 20a, 20b Wiring 30 Induction heating apparatus 32a, 32b AC power supply 34a, 34b Wiring 36a, 36b Coil 28 Coil 40 Eye part W Leaf spring 24, 26 Heating Board

Claims (3)

A method of manufacturing a leaf spring, comprising:
A clamping step of clamping the spring material formed into a predetermined shape with a pair of electrodes spaced apart in the longitudinal direction of the spring material;
An energization heating step of heating the spring material by passing a current through the spring material through a pair of electrodes;
A method for manufacturing a leaf spring.   The pair of electrodes is a method of manufacturing a leaf spring according to claim 1, wherein the pair of electrodes clamps both ends of a spring material formed in a predetermined shape.   The manufacturing method of the leaf | plate spring of Claim 2 which further has the induction heating process which heats the both ends of a spring material by induction heating.

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