JP2018144606A - Manufacturing method of headrest stay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a headrest stay which can mold a spherical surface part at a tip of the headrest stay well without remaining cut scrap inside.SOLUTION: In a manufacturing method of a headrest stay, a hemispheric spherical surface part 6 is molded by press working at a tip of a stay 2 made of metallic pipe with circle cross section. The method includes: a step of forming a tapering part 4 of a taper surface 4a by cutting the tip outer periphery of the metallic pipe and cutting the tip outer periphery in a tapered shape so that the wall thickness becomes thin gradually towards the tip; and a step of molding the spherical surface part 6 at the tip part 3 of the stay 2 by inserting the tip of the tapering part 4 into a spherical surface concave part 11 of a press die 10, and pressing the press die or the metallic pipe in the axial direction relatively.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a headrest stay, and more particularly to a method for manufacturing a headrest stay that can easily form a spherical surface at the tip of the headrest stay easily and with less man-hours.

  Normally, a headrest is detachably mounted on a seat back of an automobile seat. The headrest basically includes a headrest body (pad portion) that supports the head of the occupant and a headrest stay that is attached to the headrest body so as to protrude below the headrest body.

  The headrest stay is usually formed by bending a metal pipe, and a spherical portion is formed at the tip of both ends of the headrest stay protruding downward from the headrest body in consideration of user safety.

  Conventional spherical processing on both ends of the headrest stay has been performed by spinning or swaging to draw the tip round and form a spherical portion at the tip of the headrest stay. However, this type of drawing has poor workability, and there has been a problem that cracks and buckling tend to occur at the tip when forcible drawing is performed.

Japanese Patent Laid-Open No. 2006-165968

  Therefore, conventionally, a method for manufacturing a headrest stay, in which a spherical surface portion is processed at the tip of the headrest stay using a press die, has been proposed in Patent Document 1.

  In this conventional manufacturing method, first, the inner side of the tip of the metal pipe, which is the material of the headless stay, is subjected to boring by cutting, and the thickness of the tip of the metal pipe is reduced to about half. Next, in that state, the tip of the metal pipe is inserted into the spherical recess of the press die, the press die or the metal pipe is relatively pressurized in the axial direction, and the spherical drawing of the tip is performed in the spherical recess of the press die. Is to do.

  However, metal pipes are usually thick with a thickness of about 2 mm, and are cut with a cutting amount such that the entire inner end surface of the pipe is approximately half of the thickness. The cutting waste tends to remain in the pipe.

  For this reason, after boring, it will be necessary to take out the cutting waste remaining in the metal pipe, the inner diameter of the metal pipe of the material is usually as thin as about 10 mm, and the length of the headrest stay is, for example, It is quite long from 600 mm to 900 mm, or more than 900 mm. For this reason, in order to take out cutting waste completely, a special tool is needed, Furthermore, the operation man-hour which takes out cutting waste using them increases, and the subject which raises the manufacturing cost of a headrest stay occurred.

  The present invention solves the above-described problems, and an object of the present invention is to provide a method for manufacturing a headrest stay that can satisfactorily form a spherical surface portion at the tip of the headrest stay without leaving cutting waste inside. And

The headrest stay manufacturing method according to the present invention is a headrest stay manufacturing method in which a hemispherical spherical surface portion is formed by press working on a tip portion of a stay made of a metal pipe having a circular cross section.
Cutting the outer periphery of the tip of the metal pipe and cutting the outer periphery of the tip into a taper shape so that the thickness gradually decreases toward the tip, thereby forming a tapered portion having a tapered surface at the tip When,
Inserting the taper portion into a spherical recess of a press die, pressing the press die or the metal pipe relatively in the axial direction, and forming the spherical portion by pressing at the tip of the stay;
It is provided with.

  According to the headrest stay manufacturing method of the present invention, first, the outer periphery of the tip of the metal pipe is cut, and the outer periphery of the tip is cut into a taper shape so that the thickness gradually decreases toward the tip. Since the taper portion of the taper surface is formed, the cutting waste does not remain inside the stay of the metal pipe after the cutting process. This eliminates the need for complicated work to remove cutting waste from the metal pipe, compared to the conventional case where the inner end of the metal pipe is cut and spherically pressed, reducing man-hours and manufacturing costs. Can be reduced.

  In addition, since the cutting of the tip of the metal pipe is performed by cutting the outer periphery of the tapered tip so that the thickness gradually decreases toward the tip, a tapered portion of the tapered surface is formed thereafter. In the process of inserting the portion into the spherical recess of the press die, pressing the press die or stay relatively in the axial direction, and forming the spherical portion on the tip of the stay, As compared with the case of cutting to a uniform thickness, it is possible to satisfactorily perform the drawing of the tip with a lower press pressure. Further, when the outer peripheral portion is cut into a tapered shape, the dimensional accuracy such as the inclination angle of the tapered surface can be roughly determined, and the cutting can be easily performed.

In addition, when pressing, the tip of the tapered surface is gradually squeezed inward from the thin tip to form a spherical part, so there is no deformation such as thickening of the part squeezed inside, The reaction force of the press pressure generated in the press die is reduced as compared with the conventional case. For this reason, there is no deformation in which the outer side of the metal pipe just above the taper surface bulges at the time of the conventional press working, and the spherical portion can be formed well at the tip of the stay with a smaller pressing pressure. it can. Further, the thickness of the press die used in the axial direction (the depth dimension of the spherical concave portion) is also set to the length of the tapered surface, so that the press die can be miniaturized and the manufacturing cost can be reduced.

  Here, when the outer diameter of the metal pipe of the stay is R1, the axial length L1 of the tapered surface is preferably larger than R1 / 2 and smaller than R1 / 1.5. Further, when the outer diameter of the metal pipe is R1 and the inner diameter is R2, the cutting thickness at the tip of the tapered portion at the time of cutting is about 2/3 of the stay thickness (R1-R2) / 2. The wall thickness of the tapered end surface of the tapered portion is preferably about 1/3 of the wall thickness (R1-R2) / 2 of the metal pipe. According to this, the length L2 in the axial direction of the spherical portion of the stay in the pressed state is about ½ of the outer diameter R1 of the stay, and the spherical portion having a compact shape is excellent at the tip of the stay. Can be formed.

  According to the method of manufacturing the headrest stay of the present invention, the spherical surface portion can be favorably formed at the tip of the headrest stay without leaving cutting waste inside.

FIG. 5 is an explanatory diagram illustrating an embodiment of a method for manufacturing a headrest stay according to the present invention, in which a tip outer peripheral portion of a stay material is cut to form a tip portion having a tapered surface on the outer periphery. It is a front view of the stay which formed the front-end | tip part of the taper surface. It is explanatory drawing at the time of inserting the stay which formed the taper part in the front-end | tip in the spherical recessed part of a press die, and pressing. It is explanatory drawing of the state which press-processed the front-end | tip part of the stay and shape | molded the spherical part at the front-end | tip of a stay. It is a side view of the headrest stay which shape | molded the spherical part. It is a perspective view of the headrest stay which shape | molded the hemispherical spherical surface part at the front-end | tip.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 6, the headrest for an automobile is a pad (1) made of, for example, urethane, which is a cushion material, and a stay (headrest) in which the upper portion is embedded in the pad portion 1 and the tip portions 3 on both sides protrude downward. Stay) 2 is configured.

  The stay 2 of the headrest is formed by cutting a metal pipe P (metal round pipe) into a predetermined length, forming a hemispherical spherical surface portion 6 as shown in FIG. It is manufactured by bending the whole into a predetermined shape. In this embodiment, the stay 2 of the headrest is formed from one metal pipe P. However, the stay is formed from two metal pipes, and a spherical portion is formed at the tip of each metal pipe. These metal pipes can also be connected by welding or the like.

  The metal pipe P that is the material of the stay 2 is first cut into a predetermined length, and the outer periphery of the tip is cut into a taper shape, and the tapered surface 4a is formed on the outer periphery of the tip of the metal pipe P. The taper portion 4 is formed.

  Since this cutting process cuts only the outer periphery at the tip of the metal pipe P, it can be performed very easily with a cutting machine such as a general-purpose lathe. In addition, the cutting process is performed by cutting the outer peripheral portion of the tip of the metal pipe P into a tapered shape so that the thickness gradually decreases toward the tip to form the tapered portion 4. The cutting waste does not remain inside the metal pipe P. This eliminates the need for complicated work to remove cutting waste from the metal pipe, compared to the conventional case where the inner end of the metal pipe is cut and spherically pressed, reducing man-hours and manufacturing costs. Can be reduced.

  Moreover, when cutting the outer peripheral portion of the tip into a tapered shape, the dimensional accuracy such as the inclination angle of the tapered surface 4a can be roughly determined, and the cutting can be easily performed by a cutting machine such as a lathe.

  As shown in FIG. 1, the taper portion 4 is first cut by cutting the outer peripheral portion of the tip of the metal pipe P as a raw material to form the taper portion 4 having the taper surface 4a. Since this taper part 4 only cuts the outer peripheral part of the front-end | tip of the metal pipe P, if a general-purpose cutting lathe is used, it can be easily processed. At this time, the outer periphery of the tip of the metal pipe P is cut into a taper shape, but it may be cut so that the thickness gradually decreases toward the tip, and the cutting waste does not enter the pipe and is easily removed. Is done. The taper part 4 of the metal pipe P is finally pressed in the axial direction in the press die and curved inward to form the spherical part 6, so that an inclined surface (inclination angle, etc.) with an accurate shape is necessary. Instead, the tapered portion 4 may be formed by rough cutting.

  As shown in FIGS. 1 and 2, when the outer diameter of the metal pipe P as a material is R1, the axial length L1 of the taper portion 4 is larger than R1 / 2 and smaller than R1 / 1.5. It is preferable. When the axial length L1 of the taper portion 4 is shortened to R1 / 2 or less, when the taper portion is formed into a hemisphere by pressing, the length is insufficient, and the length is made R1 / 1.5 or more. , Too long.

  In addition, when the outer diameter of the metal pipe P is R1 and the inner diameter is R2, the thickness T2 (FIG. 1) of the metal pipe P is (R1-R2) / 2. The cutting thickness T4 (FIG. 1) at the tip is preferably about 2/3 of the wall thickness T2. That is, the cutting thickness T4 (thickness to cut) is preferably about (R1-R2) / 3. Further, the thickness T3 (FIG. 1) of the annular end surface 5 of the tapered portion 4 is preferably about １ ／ of the thickness T2, and is preferably about (R1-R2) / 6.

  Next, as shown in FIGS. 3 and 4, the tip portion of the tapered portion 4 formed by cutting the outer peripheral portion of the tip is inserted into the spherical recess 11 of the press die 10, and the press die 10 or the metal pipe P (stay 2) is inserted. ) Are moved relative to each other in the axial direction and pressed against each other, and the spherical surface portion 6 is formed at the tip of the stay 2.

  A spherical recess 11 corresponding to the shape of the spherical portion 6 to be molded is formed in the press die 10. The spherical recess 11 is formed as a hemispherical recess having a slightly larger inner diameter and depth than the hemispherical tip 3 of the stay 2. Since the depth of the spherical concave portion 11 only needs to be slightly longer than the axial length L1 of the tapered portion 4, the press die 10 can be made small and inexpensive.

  At the time of press working, the press die 10 is fixed to the fixed plate, and the metal pipe P is reciprocated in the axial direction, or the metal pipe P is fixed to the fixed plate, and the press die 10 is reciprocated in the axial direction, and the metal pipe The tip of the taper portion 4 of P is repeatedly inserted into the spherical recess 11 of the press die 10 and pressed. Since the taper portion 4 is bent, the pressing pressure during the pressing may be a normal pressure that can be generated by a general-purpose hydraulic cylinder. Therefore, the press device including the hydraulic device may have a relatively simple structure. it can.

  As shown in FIG. 4, the tip of the taper portion 4 of the metal pipe P is pressed while being pressed against the inner surface of the spherical recess 11, and is plastically deformed so that the tip of the taper portion 4 is squeezed into a hemisphere. The spherical portion 6 is pressed by repeatedly pressing the tip of the tapered portion 4 against the inner surface of the spherical concave portion 11 to press the spherical portion 6. The number of times of pressing may be about 2 or 3 times, for example. 4 can be plastically deformed so as to be easily reduced to a hemispherical shape.

  That is, the tapered portion 4 of the metal pipe P is formed with a tapered surface 4a on the outer peripheral portion so that the tip side is thin, and the annular end surface 5 at the tip is formed thin. As shown in FIG. 5, a good hemispherical spherical surface portion 6 having an axial length L2 is press-formed at the distal end portion 3 of the stay 2. . The axial length L2 of the spherical surface portion 6 is about ½ of the outer diameter R1 of the metal pipe P and is compactly formed.

  Further, at the time of this press working, the tip portion where the tapered surface 4a is processed is gradually narrowed inward from the thin tip to form the spherical portion 6, so that the reaction force of the press pressure generated in the press die 10 is small. For this reason, in the metal pipe P, a deformation in which the portion exposed to the outside immediately from the press die 10 bulges, a deformation such as a thickening of the spherical surface portion 6 or a buckling deformation, or a crack does not occur in the curved portion. The spherical surface portion 6 can be favorably pressed. In addition, the press die 10 used at this time may have an axial thickness shape (depth dimension of the spherical concave portion 11) of about the length of the tapered portion 4, and the press die 10 can be reduced in size. Manufacturing cost can be reduced.

  As described above, the stay 2 in which the spherical portion 6 is formed at the tip 3 at both ends by pressing is bent into a predetermined shape as shown in FIG. The part 1 is attached, the pad part 1 is covered with a cover, and the headrest is manufactured.

  As described above, according to this manufacturing method, the outer periphery of the tip of the metal pipe P is cut, and the outer periphery of the tip is cut into a tapered shape so that the thickness gradually decreases toward the tip. Since the taper portion 4 of the taper surface is formed, the cutting waste does not remain inside the stay 2 of the metal pipe after the cutting process, and a complicated operation for removing the cutting waste from the metal pipe P is not required. Manufacturing costs can be reduced from the reduction.

  Further, in the cutting of the metal pipe tip, the tapered outer peripheral portion is cut to form the tapered portion 4 of the tapered surface so that the thickness gradually decreases toward the tip. Is inserted into the spherical recess 11 of the press die 10, the press die or the stay is relatively pressed in the axial direction, and the spherical portion is formed on the tip of the stay, so that the tip of the tip is formed with a lower press pressure. Drawing can be performed, and the hemispherical spherical surface portion 6 can be formed satisfactorily.

  Furthermore, since the tip portion where the tapered surface 4a is processed is pressed gradually from the thin tip to the inside to form the spherical surface portion 6 during the press working, deformation such as an increase in the thickness of the tip portion that is squeezed inside is possible. The reaction force of the press pressure generated in the press die 10 is small. For this reason, there is no deformation in which the outer portion (exposed portion from the press die) of the metal pipe immediately above the taper surface 4a swells, and the spherical portion 6 is satisfactorily formed at the tip of the stay 2 with a smaller pressing pressure. Can be molded.

DESCRIPTION OF SYMBOLS 1 Pad part 2 Stay 3 Tip part 4 Tapered part 4a Tapered surface 5 Ring end surface 6 Spherical surface part 10 Press type | mold 11 Spherical recessed part P Metal pipe

Claims (3)

In the method of manufacturing the headrest stay, in which the hemispherical spherical surface portion is formed by pressing at the tip of the stay made of a metal pipe having a circular cross section,
Cutting the outer periphery of the tip of the metal pipe and cutting the outer periphery of the tip into a taper shape so that the thickness gradually decreases toward the tip, thereby forming a tapered portion having a tapered surface at the tip When,
Inserting the taper portion into a spherical recess of a press die, pressing the press die or the metal pipe relatively in the axial direction, and forming the spherical portion by pressing at the tip of the stay;
A method for manufacturing a headrest stay.   2. The headrest stay according to claim 1, wherein when the outer diameter of the metal pipe is R <b> 1, the axial length of the tapered portion is larger than R1 / 2 and smaller than R1 / 1.5. Production method. When the outer diameter of the metal pipe is R1 and the inner diameter is R2, the cutting thickness at the tip of the tapered portion at the time of cutting is about 2/3 of the stay thickness (R1-R2) / 2. 2. The method of manufacturing a headrest stay according to claim 1, wherein the thickness of the annular end surface of the tapered portion is about 1/3 of the thickness (R1-R2) / 2 of the metal pipe.

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