JPS6123526A - Production of hook - Google Patents

Abstract

PURPOSE:To elevate the intensity of a hook by performing the bend work of a hook shape with providing a rooler metal die together with a pressuer metal die, then, by performing a press work of the hook part to approx. trapezoidal shape. CONSTITUTION:A pressing die 6 is provided in opposition to the vertical wall 5 of a die device E and the roller metal die 7 which is movable to the direction of the pressing metal die 6 is arranged on the side of the vertical wall 5a. Bending work of hook shape is performed on a base material 1 with driving the roller die 7 so as to perform the movement in the peripheral direction as well as moving the pressing die 6 to the direction of the vertical wall 5a. The press work of trapezoidal shape is then performed with a press forming machine on the part where the load of the main body A of the hook is placed on. With this cold work, the intensity property of a tensile strength, etc. is elevated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing hooks used in construction, construction work, etc.

Conventionally, hooks have been manufactured by forming a round bar made of steel or the like into a hook shape by hot forging or by cold working a round bar into a hook shape.

However, since the hot forging method is processed at high temperatures, oxidized scale is generated on the surface of the round bar, which not only causes variations in shape and dimensions, but also causes the metal crystals of the round bar itself to deteriorate due to heating. It has the disadvantage that it becomes coarse and the mechanical strength of the round bar decreases.

On the other hand, in the conventional cold working method, a steel round bar is simply inserted between a die or rollers and bent into a hook shape, so there is compressive stress inside the bent part. Moreover, tensile stress is internalized externally, and this deformation stress becomes an obstacle in the molding process of the hook, which not only makes it impossible to manufacture the hook with high precision, but also poses problems in terms of strength.

The present invention has been made to eliminate the drawbacks of such conventional methods, and its technical idea is related to the improvement of the cold working method, and its gist is as follows: It has a shaped molding space, and has a bar supply opening at the bottom of the space, and has a circular surface facing a vertical wall at the top of the L-shaped space's supply opening, and extends toward the vertical wall. Using a mold with a presser die that moves back and forth, and a roller die that is located on the vertical wall side and does not move in the direction of the presser die,
A metal bar is fed through the supply port and fixed with its tip positioned between the presser die and the roller die.The presser die is directed toward the vertical wall, and the roller die is placed between the presser die and the roller die. The end of the supplied bar is bent into a hook shape by movement in the circumferential direction, and then this hook part is suspended in a press die to apply a load. A method for manufacturing a hook, characterized in that the hook is press-worked so that the portion is at least approximately trapezoidal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be specifically described below with reference to the accompanying drawings showing examples thereof.

First, the base material 1 of the hook is a bar made of steel or the like, for example, a round bar made of steel or the like whose tip end 2 is cut into a tapered shape as shown in FIG.

and a hook forming mold apparatus, such as the one shown,
It has a side wall-shaped forming space 3, with a bar supply port 4 opening at the bottom of the space 3, and a surface facing a vertical wall 5 above the outlet of the supply port 4 of the forming space 3. is circular, and is provided with a presser die 6 that can move back and forth in the direction of the vertical wall 5, and a roller die 7 that is located on the vertical wall 5a side and can move in the direction of the presser die 6. E is used to feed the base material 1 from the supply port 4 of the device, and the tip end 2 of the base material is fed.
is fixed between the presser die 6 and the roller die 7, and the presser die 6 is moved in the direction of the vertical wall 5 as shown by the arrow, and the roller die 7 is moved around the circumference. Then, the supplied base material 1 is bent into a hook shape to form the hook body A).

That is, since the hook body A that has gone through the above steps is manufactured by bending as described above, the inside of the hook body A that has received the bending force has compressive residual stress -
6R1, and the outside has a tensile stress +6R2.

These stresses -6R1 and +6R2 increase as the bending process of the hook body A progresses, and especially when the compressive stress -6R1 increases, the hook body naturally deforms toward the inner surface of the curved part against the tensile stress +〇R2. Become.

Furthermore, the deformation stress existing in the hook body A does not only cause natural deformation, but also increases the pressing force of the presser mold and roller mold due to the resistance pressure of the stress during the hook forming process. This causes problems such as pressure and difficulty in hook-shaped bending.

Therefore, in the method of the present invention, the hook body A is further reshaped by press working, and the orientation of the metal crystals in the bent portion is corrected, so that the stress remaining in the hook body A is caused to undergo crystal displacement. The purpose is to manufacture a hook of a desired shape.

Specifically, a known trapezoidal press molding machine or the like is used to bend the portion located from the proximal end of the hook to the distal end, which is indicated by The bent portion X2 bent in the space 3 and the vicinity thereof, and the bent portion X3 bent in the direction of the presser die 6 by the roller die 7 and the vicinity thereof are made wider at least on the inner side than in the width direction, and the outer surface Pressing is performed to form a substantially trapezoidal shape with slightly narrower sides, and the tip portion indicated by ×4 is rounded, thereby correcting the stress in the corresponding portion.

However, in the hook manufacturing method according to the present invention,
A bar material serving as the base material 1 is bent using the molding die device E to form the hook main body A, and thereafter the main body A is subjected to a trapezoidal forming process using a press molding machine. Since each of these steps is carried out in a cold atmosphere, the metal crystals in the hook body A after treatment become fine, unlike the conventional hot treatment, where the metal crystals become coarse. Moreover, since it is hardened by cold working, its mechanical properties, such as tensile strength, are significantly improved due to the hardening phenomenon, and the yield point is accordingly increased.

In addition, the hook body A after press molding has a substantially trapezoidal part on which the hanging load is applied, and the cross-sectional shape of the relevant part is made thicker, thereby increasing the section modulus, so that it can be used as a hook. It increases the strength.

Example 1 The tip of a carbon #steel rod (320G) was cut into a tapered shape, and the tip was inserted into the supply port of the hook forming mold device,
A hook-shaped bending process was performed by moving the presser mold and the roller mold of the apparatus, and moving both molds in the circumferential direction.

Subsequently, the hook-shaped steel rod was cold-pressed from above and below using a press-forming machine, and the bent portion of the steel rod was formed into a trapezoid shape to produce a hook.

Next, the hook manufactured according to Example IJ and the conventional method (
Regarding hooks manufactured by hot forging method) JIS
Comparing the mechanical properties based on Z 2241,
The hook according to this example has a yield point of 30% compared to the conventional product.
The tensile strength increased by 25%.

Furthermore, it was found that the fatigue strength characteristics based on JIS Z 2273 were increased by 28% compared to the conventional product.

In addition, regarding the case where the hook is manufactured by the process according to the present invention for base materials other than the carbon steel rod used in Example 1, for example, steel materials and nonferrous metals such as alloy steel, stainless steel, bronze, and brass. It was also confirmed that the mechanical properties of each of these products were improved compared to conventional products.

As described above, the hook manufacturing method of the present invention has a side-sided molding space, a bar supply port is provided at the bottom of the space, and a vertical wall is provided above the supply port exit of the L-shaped space. Using a molding die, a presser die with a circular surface and a presser die that moves back and forth in the direction of the vertical wall is arranged opposite to the presser die, and a roller die that is located on the vertical wall side and can move in the direction of the presser die is used. A metal bar is fed through the supply port, and the end of the metal bar is brought into contact with the presser die, and by moving in the circumferential direction, the end of the supplied bar is bent into a hook shape. This is a method of manufacturing a hook by forming a hook body, and then pressing the hook body with a press molding machine so that the part on which the hanging load is applied forms at least a substantially trapezoidal shape. All the processes are carried out in a cold atmosphere, and the crystal grains of the hook are refined by the cold work hardening phenomenon, so the mechanical strength of the hook, that is, its yield point and tensile strength, will change during the processing process. It is convenient to be granted.

In particular, in the method of the present invention, after the hook body is formed as described above, the curved portion of the hook, which is subjected to a strong hanging load, is reshaped into a substantially trapezoidal shape by press working, and its workability is improved. As the section modulus is increased, its strength is further strengthened.

In addition, in the manufacturing process of the present invention, unlike the conventional hot forging method, everything is processed in a cold atmosphere, so the heating process etc. can be omitted, making it possible to simplify the process and also reduce the generation of oxide scale due to heating. Because of this, the material yield is high and hooks can be manufactured economically.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory views showing the manufacturing process of the hook according to the present invention, and FIG. 3 is an explanatory view showing the shape of the hook after press molding. 1... Base material 2... Tip part 3... L forming space 4... Supply port 5... Vertical wall
6... Presser mold 7... Roller mold A... Hook body E... Molding mold device-8R
1...Ml stress +BR2...41 Multi-length stress Figure 1 Figure 3 Procedural amendment January 7, 1985 Mr. Manabu Shiga, Commissioner of the Patent Office 1. Indication of the case ' 3. Case of the person making the amendment Relationship with: Patent applicant 2-2-90 Sakaiyo, Nishi-ku, Osaka City Kondo Tekko Co., Ltd. Representative: Kazuto Kondo 4, Agent ■533 Higashiroschi, 1-20-14 Higashinakajima, Higashiyodoyo-ku, Osaka City John Bill 5, Date of amendment order Voluntary 6, Column for detailed explanation of the invention, column for brief explanation of drawings, and drawings in the specification subject to amendment, 7. Contents of amendment) Page 6, line 13 of the specification Next, ``Also, the bent portion X2 and its vicinity and the bent portion X3 and its vicinity of the hook are made into a substantially semicircular shape on the inner side with respect to the width direction, and the outer side is shaped like a semicircle, as shown in Fig. 4. It is also possible to have a narrow shape X2",
It is also possible to correct the stress by creating a semicircular shape X2'', X3'' which is smaller than the inner surface through an intermediate portion having a narrow width on the outer surface. ” to join. 2) On page 10, line 9 of the specification, "This is an explanatory diagram showing the shape." was replaced with "Explanatory diagram showing the shape. Figures 4 and 5 are the same and show different aspects. This is an explanatory diagram.'' is added. 3) Add Figures 4 and 5 as shown in the attached sheet. Figure 4 Figure 5

Claims (1)

[Claims] It has a molding space with an L-shaped side surface, and a bar material supply port is opened at the bottom of the space, and above the supply port outlet of the L-shaped space, the surface is circular and faces a vertical wall, and extends in the direction of the vertical wall. Using a mold with a presser die that moves back and forth, and a roller die that is located on the vertical wall side and can move toward the presser die,
A metal bar is fed through the supply port and fixed with its tip positioned between the presser die and the roller die, with the presser die directed toward the vertical wall and the roller die directed toward the presser die. And,
By making a movement in the circumferential direction, the end of the supplied bar material is bent into a hook shape, and then,
A method for manufacturing a hook, characterized in that the hook portion is pressed using a press molding machine so that the portion on which the hanging load is applied forms at least a substantially trapezoidal shape.