JPH05337592A - Manufacture of boss for core metal in steering wheel - Google Patents

Abstract

PURPOSE:To simplify a casting mold and to prevent uneven accuracy by allowing the excess inner material to flow into releasing gap formed by an upper and a lower dies, forming into concentric circular state with a cylindrical body and executing edge cutting in the following process to form a locked flange part. CONSTITUTION:A boss 84 used at the time of manufacturing a core metal in a die casting-made steering wheel is manufactured by the forging. A preformed cylindrical base stock having recessed parts at the upper and the lower parts is held while having the releasing gap on the outer periphery at the intermediate height position of the cylindrical base stock by the upper and the lower dies 60, 61, and by flowing the inner material in the cylindrical material into this releasing gap to form the almost concentric circular state of the preformed flange part 68. Successively, the edge-cutting is executed to a part of this preformed flange part 68 to form the locking flange part 80. By this method, the casting mold is simplified, and also even if there is unevenness in the wt. of the base stock, the unevenness of the flange part shape can be corrected by the edge-cutting.

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 boss used for manufacturing a steering wheel core metal (sometimes abbreviated as "wheel core metal") made of die casting by forging.

[0002]

2. Description of the Related Art The shape of a boss used when a core metal is manufactured by a conventional die casting is a cylindrical body in order to prevent the boss from being pulled out from the boss plate portion (formed by die casting) and to prevent rotation. In general, the outer peripheral portion at the intermediate height position has a hexagonal detent collar portion.

As a method of manufacturing the boss having the above-mentioned shape by forging, there is, for example, the method of the following constitution described in Japanese Patent Laid-Open No. 2-171382.

[In a method for manufacturing a boss for a steering wheel in which a boss plate to which a wheel ring is fixed via spokes is fixed to the outside, punches are pressed on the upper and lower surfaces of the material in the axial direction, respectively. First step of forming the recesses and chamfering the edges of the recesses, and pressing a pair of upper and lower recess forming punches into the pair of upper and lower recesses of the material to form the depth of each recess. And a second step of axially extending the material, a third step of axially penetrating both recesses of the material to form a through hole, and a lower end opening on the inner surface of the through hole on the lower side of the material. Fourth step of forming an inclined surface in which the inner diameter of the through hole gradually increases toward the end and flowing excess material at the time of forming the inclined surface to form a flange portion at a predetermined position on the outer surface of the material The method of the boss for a steering wheel, characterized in that as and a fifth step of performing serration into a predetermined position of the through-hole inner surface other than the inclined surface forming portion of the through hole of the material. "

[0005]

However, it has been found that when the boss for core metal having the above-mentioned shape is manufactured by the above method, the following problems occur.

That is, in the step of forming the anti-rotation collar portion in the above-mentioned fourth step, the collar portion is usually shaped in a hexagonal shape in a closed type. For this reason, the casting mold (upper and lower dies) becomes complicated, and when the material weight varies, the shape of the flange on the outer surface tends to vary.

In view of the above, the present invention does not require a forging die having a complicated shape for forming a collar portion at the time of manufacturing, and moreover, the shape of the collar portion on the outer surface is less likely to vary, and a boss for a steering wheel core metal is provided. It aims at providing the manufacturing method of.

[0008]

A method of manufacturing a wheel core metal boss according to the present invention solves the above problems by the following constitution.

A method for manufacturing a boss used for manufacturing a die-cast steering wheel core metal by forging. (1) A preformed tubular material having recesses on the upper and lower sides is manufactured by an upper die and a lower die. A step of forming a substantially concentric preformed brim portion by holding an open gap on the outer periphery of the intermediate height position of the tubular material and allowing the internal material of the tubular material to flow into the open gap. 2) At least each step of cutting off a part of the preformed collar portion to form a rotation preventing collar portion.

[0010]

Next, a method for manufacturing a wheel core metal according to the present invention will be described in detail based on an embodiment.

A. (1) Material removal: Although a rod-shaped material that has been cut in advance may be used as a material, in this embodiment, material removal is performed by the following method (see FIG. 2).

The coil-shaped wire (steel material) 14 set on the uncoiler 12 is applied to the straightening roller group 18 of the straightening machine 16.
The wire rod 14 is passed through the gap between the wires to correct the bending habit of the wire rod 14. At this time, a steel material having a thickness of 20 to 22 mmφ is used, for example.

The wire rod is fed into the cold forging device 20, and a cutting device (not shown) attached to the device 20.
The first material 22 is prepared by cutting into a predetermined length with. The cutting length is, for example, 21 to 22 mm.

(2) End face straightening step (FIG. 1 (1)): The first raw material 22 is held by the first lower punch 28 in the forming round hole 26 of the first die 24 by the first upper punch 30. The second raw material 32 is obtained by pressing to correct the end face. At this time, the central portions of the first lower punch 28 and the first upper punch 30 are slightly bulged, and recesses 34, 34 are formed at the central portions of both end surfaces of the second material 32. Here, the second material 32 contracts from the first material 22 in height and spreads laterally slightly.

(3) First backward extrusion step (FIG. 1 (2)): The second raw material 32 is set in the forming round hole 37 of the second die 36 and the upper surface is held by the second upper punch 38. Then, the second lower punch 40 is press-fitted into the lower end surface of the second material, and the lower side preforming recess 42 is formed by rearward extrusion.
And Here, the third material 44 expands from the second material 32 in height and spreads laterally to some extent.

(4) Second backward extrusion step (FIG. 1 (3)): The third raw material 44 is set in the forming round hole 48 of the third die 46, and the third lower punch 50 is placed in the lower preforming recess. The third upper punch 52 is press-fitted into the upper end surface of the third material 44 in a state of being inserted and held in the second material 42, and the upper preforming recess 54 is formed by rearward extrusion to form the fourth material 56. At this time, the forming portion of the third lower punch 50 has a truncated cone shape, and at the same time, the lower preforming recessed portion 42 becomes a preformed tapered recessed portion 58 having a diameter expanded at the lower end. Here, the fourth material 56 becomes a cylindrical body having a height extending from the third material 44 and slightly spreading laterally, and having a thick film portion 57 in the middle. ..

(5) Preforming collar portion forming step (FIG. 1 (4)
): The above-mentioned fourth material 56, upper die 60 and lower die 6
Set to the fourth die 62 consisting of 1. That is, above
In the lower die 60, 61, the intermediate height position, that is, the thick film portion 5
Set with an open gap 63 on the outer periphery at the 7th position. Further, the size of the open gap 63 is 6 to 8 mm. Then, the fourth lower punch 64 is inserted into the preforming tapered concave portion 58, and the fourth upper punch 66 is inserted into the preforming concave portion 54 and pressed respectively. Then, the fourth material 56 contracts in the height direction and the thick film portion 57 becomes the book thickness film portion 59, so that the excess material inside flows into the open gap 63 formed in the fourth die 62. A concentric preformed brim 68 is formed to form the fifth material 70. Here, an upper concave portion 71 and a lower tapered concave portion 73 having a finished size are formed in the fifth material 70. At this time, the diameter of the preforming collar 68 is, for example, 27 to 29 mm when the main body diameter is 24 mm.
Becomes

(6) Punching process of book meat film part (FIG. 1 (5)):
The fifth material 70 is set in the fifth die 754 including the upper die 72 and the lower die 74. That is, with the upper and lower dies 72 and 74, the preformed collar portion 68 of the fifth material 70 is formed.
In the state of sandwiching, the remaining book meat film portion 59 is punched out by the punching punch 76, and the ironing rod (not shown) and the punching burr are removed to obtain the sixth material 78.

(7) Edge-cutting step of the preformed collar (Fig. 1)
(6)) The preformed brim 68 of the sixth material 78 is trimmed using a cutting machine attached to the cold forging device 20 to obtain an intermediate height as shown in FIG. A boss product having a shape having a detent collar portion 80 at a position. At this time, the remaining margin of the edge-cutting portion 82 is usually 0.2 to 0.5 mm.
Shall be At this time, the number of the edge cutting portions 82 of the detent brim portion 80 is two in the illustrated example, but may be one or 3 to 6 as long as the detent function is described later.

(8) The boss 84 thus manufactured is stored in the product container 88 by the conveyor 86 after the cleaning process. If necessary, the product is processed through a plating process.

B. Usage Mode of Boss The boss 84 manufactured as described above is set in a die-casting die of a steering wheel core metal together with a pipe material 86 forming a wheel portion to die-cast the core metal (see FIG. 4). .. After the molding, the wheel core metal has a flange portion 80 that is not a perfect circle in the boss portion, and exerts a reliable anti-rotation action with the post plate portion 88 that is die-cast.

The technical scope of the present invention is not limited to the above-described embodiments, but extends to various modes within the scope of the claims.

Further, although the boss having the shape shown in FIG. 3 can be formed by cutting a round bar to have a concentric circular collar portion and then trimming the collar portion, it can be formed (a hexagonal shape only by conventional cutting). The number of man-hours is smaller than that in the case of forming the brim portion.

[0024]

The operation and effect of the wheel core metal boss according to the present invention has the following operation and effect due to the above-mentioned structure.

Conventionally, the collar portion of the detent was directly formed into a hexagonal shape with a forging die, whereas in the present invention, in the step of forming the boss by forging, an extra gap is formed in the open gap formed by the upper and lower dies. The inner material is made to flow in and is formed into a concentric shape with the cylindrical body, and the edges are trimmed in a later step to form a rotation-stop collar portion. For this reason, a complicated casting mold for forming the collar is simplified, and even if there is a variation in the material weight, the variation in the shape of the collar can be corrected by the edge-cutting process, and the variation in the accuracy of the shape of the retaining collar is prevented. Is unlikely to occur.

[Brief description of drawings]

FIG. 1 is a schematic view showing a manufacturing process of a wheel core metal boss according to the present invention.

FIG. 2 is an overall schematic view of a boss manufacturing apparatus used in the manufacturing method of the present invention.

FIG. 3 is a perspective view showing an example of a wheel core metal boss manufactured by the present invention.

4 is a cross-sectional view of a wheel core metal die-cast using the boss of FIG.

[Explanation of symbols]

 54 Upper Preliminary Forming Recess 56 Fourth Material 57 Thick Film 58 Preforming Tapered Recess 60 Upper Die 61 Lower Die 62 Fourth Die 63 Open Gap Formed in Upper and Lower Dies 64 Fourth Upper Punch 66 Fourth Lower Punch 68 Preliminary Molded brim 70 Fifth material 78 Sixth material 80 Non-rotating brim 82 Ear cutting section 84 Wheel core metal boss

Front Page Continuation (72) Inventor Toru Isono 1 Nagachibata, Ochiai, Kasuga-cho, Nishikasugai-gun, Aichi Toyoda Gosei Co., Ltd. In the company

Claims (1)

[Claims] 1. A method for manufacturing a boss used for manufacturing a die-cast steering wheel core metal by forging, comprising: (1) forming a preformed tubular material having recesses in the upper and lower parts, A step of holding an open gap on the outer periphery of the intermediate height position of the tubular material with a die, and allowing the internal material of the tubular material to flow into the open gap to form a substantially concentric preformed brim portion And (2) a step of cutting a part of the preformed collar portion to form a detent collar portion, and a step of manufacturing the steering wheel core metal boss.