JP3232900B2 - Manufacturing method of bulge nipple - Google Patents

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 bulge nipple which is inserted into a hose and receives a fastening force when an intermediate joint is fastened to a hose, and more particularly, to a method for continuously mass-producing bulge nipples by transfer molding. To possible manufacturing methods.

[0002]

2. Description of the Related Art For example, when an intermediate joint is fastened to a hose, a nipple is inserted into the hose to increase the fastening strength of the intermediate joint by receiving a caulking force. This nipple must have an outer diameter larger than the inner diameter of the hose in order to prevent the nipple from slipping out and ensure positioning.However, if the outer diameter of the entire nipple is larger than the inner diameter of the hose, the nipple insertion load will be extremely large. It becomes large and the man-hour becomes large.

[0003] In recent years, bulge nipples have been used which have a bulge portion in which only the outer diameter of the central portion is increased, and the outer diameter of the general portion on both sides of the bulge portion is slightly smaller than the inner diameter of the hose. According to this bulge nipple, the length of the bulge portion is shorter than before and the outer diameter of the general portion is smaller than the inner diameter of the hose, so that the insertion load is small and the bulge nipple can be easily inserted into a predetermined position in the hose, and the bulge nipple can be easily removed. Is prevented.

A product having a shape such as a bulge nipple is generally manufactured by cutting a pipe material.

[0005]

However, the shape of the bulge nipple has a bulge diameter of about 3.65 mm and a length of about 1 mm.
Some bulge nipples are as small as about 7 mm. To manufacture such a bulge nipple by a manufacturing method such as cutting, the number of steps is increased, the yield and productivity are poor, and there is a problem in cost.

The present invention has been made in view of such circumstances, and has as its object to enable mass production of small bulge nipples with high shape accuracy.

[0007]

According to the present invention, there is provided a method of manufacturing a bulge nipple, comprising: a bulge nipple having a substantially cylindrical shape and comprising a general portion and a bulge portion having a diameter increased at the center of the general portion. It is a manufacturing method, comprising: a first step of forming a bottomed cylindrical drawing cylinder by drawing from a sheet metal; and forming a bulge portion by pressing the drawing cylinder with a punch to form a bulge cylinder. A second step, and a third step of punching the bottom of the bulge cylinder, wherein the second step includes a lower die, an upper die, and a first punch that presses an end surface of the drawing cylinder.
A second punch in the form of a rod inserted into the inside of the drawing cylinder, a knockout pin for pressing the bottom of the drawing cylinder from the outside in the axial direction, and a mold for forming a mold surface forming a lower bulge portion and a general portion. A press die having a first oil release passage opening at the boundary between the surfaces, a second oil release passage opening at the distal end surface of the second punch, and a third oil release passage opening at the distal end surface of the knockout pin. It is characterized by performing using.

[0008]

According to the manufacturing method of the present invention, a drawing cylinder is formed by drawing in the first step. This first step is performed in the same manner as in the ordinary drawing, and the drawing cylinder having a target length is generally obtained by drawing several times. A bulge portion is formed on the aperture barrel by press working in the second step.

Here, the working oil is used for the press working, but the drawing cylinder is a bottomed cylinder having a diameter of several millimeters in some cases, and the resistance of the oil accumulated inside or between the mold and the work is reduced. It has been clarified that the machining accuracy may be reduced. Therefore, in the manufacturing method of the present invention, the first oil release passage opening at the boundary between the mold surface forming the lower mold bulge portion and the mold surface forming the general portion, and the second oil opening passage opening at the tip end surface of the second punch. The second step is performed by using a press die having an oil release passage and a third oil release passage opened at the tip end surface of the knockout pin.

By providing the first oil release passage, the oil between the mold surface and the work can be released, the accuracy of the shape of the boundary between the bulge portion and the general portion is improved, and the occurrence of dripping is prevented. Further, by providing the second oil release passage, the oil inside the throttle cylinder can be released, and the occurrence of burrs at the bulge portion is prevented. Further, by providing the third oil release passage, the accuracy of the length is improved, and the occurrence of burrs in the bulge portion is prevented.

In the third step, the bulge cylindrical body having high shape accuracy obtained in the second step is punched out to obtain a bulge nipple.

[0012]

The present invention will be described more specifically with reference to the following examples. FIG. 1 is an enlarged perspective view of a bulge nipple manufactured in this embodiment. The bulge nipple 1 has a bulge portion 10 having an outer diameter of 3.65 mm and an outer diameter 3.2 m extending on both sides of the bulge portion 10.
m, and the boundary between the bulge portion 10 and the general portion 11 is a conical surface portion 12. (First Step) A sheet metal 20 having a thickness of 0.5 mm is prepared, and FIG.
As shown in (1), a drawn cylinder 2 having a predetermined length is formed by a plurality of drawing processes. (Second step) Next, using the press die shown in FIGS. 3 and 4,
A bulge portion 10 is formed at the center of the aperture barrel 2.

The press die includes a lower die 3, an upper die 4, a first punch 5 for pressing the end face of the aperture cylinder 2, and an aperture cylinder 2.
It comprises a cylindrical second punch 6 inserted into the inside and a knockout pin 7. The lower die 3 is formed with four first oil release passages 32 (only one is shown in the figure) that open at the boundary between the bulge-shaped surface 30 and the conical-shaped surface 31. The second punch 6 is provided with a second oil release passage 60 which is opened at the tip end surface. Further, the knockout pin 7 is formed with a third oil release passage 70 that opens at the tip.

First, the stop cylinder 2 is disposed on the lower die 3, and the upper die 4 and the knockout pin 7 are assembled. Then, the first punch 5 and the second punch 6 press the drawing cylinder 2,
The diameter of the aperture barrel 2 is increased, and as shown in FIG.
The bulge cylindrical body 2 ′ has a bulge portion 10 and a conical surface portion 12 having a shape along the 0 and the conical surface 31. At this time, the aperture cylinder 2
The oil interposed between the lower mold 3 and the lower mold 3 escapes from the first oil escape passage 32 to the outside. Therefore, the so-called sagging failure in which the oil remains and the shape accuracy of the conical surface portion 12 is reduced is prevented. The oil remaining in the throttle cylinder 6 escapes from the second oil escape passage 60 to the outside. Therefore, the throttle cylinder 2 is excessively pressed by the remaining oil, and the occurrence of burrs between the upper mold 4 and the lower mold 3 is prevented. Further, the oil interposed between the knockout pin 7 and the throttle cylinder 2 escapes from the third oil escape passage 70 to the outside, so that the accuracy of the length is secured and burrs are prevented.

The accuracy of the length of the stop cylinder 2 is also important. When the entire length of the aperture barrel 2 exceeds 17.75 mm, burrs are generated, and when it is 17.45 mm or less, sagging failure is observed. Therefore, in order to obtain the effect of the oil escape passage, it is necessary to control the entire length of the throttle cylinder 2 within this range, and if it is outside this range, the effect of the oil escape passage cannot be obtained. (Third Step) The molded bulge cylinder 2 ′ is released by opening the mold and then raising the knockout pin 7. Then, the bulge nipple 1 shown in FIG. 1 is manufactured by being arranged in a punching die (not shown), punching out the bottom portion, and rounding both end surfaces by curling.

[0016]

According to the method for manufacturing a bulge nipple of the present invention, bulge nipples having high shape accuracy without defects such as burrs and sagging are continuously and stably mass-produced by transfer molding using drawing. be able to. Therefore, productivity is significantly improved and production costs are reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a bulge nipple manufactured according to an embodiment of the present invention.

FIG. 2 is an explanatory view schematically showing a first step of one embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a press die before performing a second step in one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a press die in a state immediately after a second step in one embodiment of the present invention.

[Explanation of symbols]

1: bulge nipple 2: diaphragm cylinder
3: Lower mold 4: Upper mold 5: First punch
6: Second punch 7: Knockout pin 10: Bulge part 1
1: General part 12: Conical surface part 32: First oil release passage
60: Second oil release passage 70: Third oil release passage

────────────────────────────────────────────────── ─── The continuation of the front page (72) Inventor Ryuji Shibuya 1 Ochiai, Ogai, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. (56) References JP-A-7-148536 (JP, A) JP-A-3-94927 (JP, A) JP-A-60-257935 (JP, A) JP-A-56-30040 (JP, A) JP-A-50-151754 (JP, A) JP-A-6-15827 (JP, A) U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21D 51/16 B21D 39/08 B21D 39/20 B21D 41/02 B21D 35/00

Claims (1)

(57) [Claims] 1. A method of manufacturing a bulge nipple having a substantially cylindrical shape and a bulge portion formed of a general portion and a bulge portion having an enlarged diameter at the center of the general portion. A first step of forming a body, a second step of forming a bulge portion by pressing the drawn cylinder with a punch to form a bulge cylinder, and a third step of punching the bottom of the bulge cylinder. The second step comprises: a lower die, an upper die, a first punch for pressing an end surface of the drawing cylinder, a rod-shaped second punch inserted into the inside of the drawing cylinder, and A knockout pin for axially pressing the bottom of the throttle cylinder from the outside, a first oil release passage opening at a boundary between a mold surface forming the bulge portion and a mold surface forming the general portion of the lower mold; A second oil release passage opening at the tip end surface of the second punch; Method for producing a bulge nipple and performing using a press die having a third oil release passage which is opened to the end surface.