JPH01166841A - Continuous cold forming method - Google Patents

Abstract

PURPOSE:To enable continuous forging in a short time by executing a 2nd forging and after by the existence of a thermal reacting lubricant and executing the succeeding forming prior to starting of the age hardening of after forming in case of continuously executing plural cold forging stages. CONSTITUTION:A blank stock is set to the cavity 13 of a die device 10, formed by forging by a punch 12 from the upper part and made an intermediate part forming a chemical conversion film. This intermediate part is then inputted into the cavity 23 of the die device 20 filling a thermal reacting liquid lubricant in advance to form a solid lubricating film on the surface of the intermediate part and the drawing is executed by a punch 22 within the time (in 18sec) until an age hardening starts on the intermediate part. For the liquid lubricant those which adds calcium additive and sulfurized oil and fat to a naphthenic base oil are used. The intermediate part is then input into the cavity 33 of the die device 30 filled with a lubricant, a spline is also formed simultaneously with the drawing by a punch 32 prior to starting of the age hardening and a counter shaft is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for continuously forging a material at a temperature equal to or lower than its transformation point (recrystallization temperature).

(Prior art) Japanese Patent Application Laid-Open No. 115343/1986 is a conventional technology that produces a product by sequentially performing multiple forging (heading) processes on a material.
The one disclosed in No.

In this method, a material (billet) is sequentially formed into an anchor bolt using a transfer press machine equipped with a plurality of forging dies in parallel.

(Problems to be Solved by the Invention) The conventional method described above has problems with lubrication and age hardening (work hardening).

First, when forging is performed, a lubricating film must be formed on the surface of the material, otherwise seizures may occur. Therefore, a chemical conversion film must be formed on the surface of the material by bonding, or the material or mold must be I try to spray lubricating oil towards it.

However, regardless of the size of the forming rate, the lubricating film formed by the bonding process drastically reduces the film thickness after one molding, and cannot be continuously formed. The disadvantage is that the lubricating effect is lost due to the heat generated. Furthermore, when lubricating oil is used, it is difficult to apply it uniformly to the entire surface of the material and mold, and treatment of the oil after application is troublesome, and unlike chemical conversion coatings, there is simply an oil film on the surface of the material. Therefore, if the molding pressure is increased, the oil film will run out and seizure will occur.

On the other hand, when molding is performed below the transformation point (recrystallization temperature), age hardening occurs. The present inventor found that this age hardening becomes noticeable after a certain period of time has passed after molding, but in conventional methods, a lubricating film is formed before each molding process, so age hardening becomes noticeable. Therefore, it is necessary to perform annealing before forming, which is extremely disadvantageous in terms of production efficiency.

(Means for Solving the Problems) In order to solve the above problems, the present invention uses a liquid lubricant that forms a solid lubricant film on the surface of the material when it comes into contact with the material whose temperature has been raised in the previous process of molding. The second and subsequent mold cavities are filled with rice, and the time from each forging to the next forging is made so that age hardening does not become noticeable.

(Function) By filling the mold cavity with a heat-reactive liquid lubricant in advance, a lubricating film can be formed just by placing the material into the cavity, allowing for continuous forging in a short period of time. Can be done.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

Figure 1 is a sectional view of a vertical forming press machine for carrying out the method of the present invention, and Figures 2 (A) to (D) are billet (
It is a diagram illustrating the process from a raw material to a countershaft as a product, and shows an example in which three forging steps are performed continuously.

The vertical forming press machine is the mold device 1 that performs the first forging.
0 is placed on the left side in the figure, the mold device 20 that performs the subsequent forging is placed on the right side, and the mold device 30 that performs the final forging is placed in the center. 20
．． 30 is provided with a supply/discharge device 40 for supplying and discharging lubricant.

Each mold device 10, 20, 30 has a plurality of molds 11...,
21..., 31... and bunches 12, 22.32, and cavities 13, 23.33 are formed so as to penetrate each mold 11, 21.31. Steps 14, 24, 34 for squeezing the material to a small diameter are provided on the inner peripheral surface of the forming mold 11.21.31, and in particular, splines are provided on the inner peripheral surface of the mold of the mold device 30 that performs the final forging. A blade portion 35 is provided for forming.

Moreover, a cavity 23.
A lubricant supply path 26.36 is formed at the top of the cavity 23.33, and a lubricant discharge path 27.37 is formed at the bottom of the cavity 23.33 from the middle to the bottom of the mold device 20.30. is forming.

On the other hand, the lubricant supply/discharge device 40 has a supply vibrator 42 connected to the supply path 26.36 and a discharge vibrator 43 connected to the discharge path 27.37 facing inside the lubricant tank 41,
A check valve 46 and a solenoid valve 47 check the lubricant pumped up by a pump 45 driven by a motor 44.
The liquid is fed into the supply path 26.36 via the feed line 26.36.

Further, a relief valve 48 is provided in the middle of the discharge vibe 43 that connects the tank 41 and the discharge passage 27.37. This relief valve 48 has a structure in which the pressure from the bypass passage 49 acts B against the spring 50 (right side in Figure 1) to open the passage, and when the pressure in the bypass passage 49 decreases, the passage is closed. It becomes.

Note that a branch pipe 51 is connected between the supply vibrator 42 and the discharge vibrator 43.
These branch pipes 51 and 52 are also provided with relief valves 53 and 54 similar to those described above, so that the lubricant is released into the discharge pipe 43 when the pressure inside the supply vibe 42 exceeds a predetermined value. ing.

However, in the present invention, a thermally reactive liquid lubricant is used that forms a solid lubricant film on the surface of the material when heated. The liquid lubricant is a naphthenic base oil with calcium additives (15.0 to 0 to 25, Owt!k) and active or inactive sulfurized fats and oils (sulfur content of 4.0 to 25, Owtk).
7. Owt! k), and further add Cu, Z as necessary.
Fine powder (1
, Owtk ~5. Owt! k), chlorinated paraffin (
2, Owtt~30wt96) is used.

The reason why the lubricant is made of the above substances is as follows.

First, active or inactive sulfurized oils and fats do not react under normal conditions, but after the oil film caused by the oil-based agent is broken, that is, when the material temperature rises due to frictional heat and forging heat, they chemically decompose, causing mold and material damage. It reacts with iron sulfide to form a solid lubricant film with excellent pressure resistance as shown in FIG.

As shown in Figure 4, active sulfurized oils and fats and inactive sulfurized oils and fats have different operating temperature ranges, with the former being appropriate at 150-300°C and the latter at 250-400°C. Therefore, it is preferable to use them properly depending on the molding rate and the like.

In addition, calcium-based additives (extremely fine powder of 1 μm or less)
The addition of naphthenic base oil improves the retention of the lubricating film and delays the time it takes for the coefficient of friction to rise, and naphthenic base oil has superior solubility of additives compared to paraffinic base oil, and Wear resistance is improved by adding non-transition metal powders such as Cu and Zn.

Next, a cold continuous forming method using a vertical forming press machine will be described.

First, as shown in Fig. 2 (A), billet W is used as a material.
Prepare 1. A chemical conversion film is previously formed on the surface of this billet W1 by bonding and filling.

The above billet W1 is set in the cavity 13 of the mold device 10, and forged from above by the bunches 12 to obtain the intermediate product W2 shown in FIG. 2(B).

Then, the intermediate product W2 is discharged from the mold device 10,
It is put into the cavity 23 of the mold device 20. here,
The time from the end of forging by the mold device 10 to the start of forging by the mold device 20 is within the time until age hardening begins after molding. Specifically, as shown in FIG. 5, since the material hardness after forming reaches HRB85 after 18 seconds, it is preferable to start forging using the mold device 20 within 18 seconds.

Further, in forging using the mold device 20, the cavity 23 is filled with the liquid lubricant in advance. Then, the intermediate product W2, which has been drawn to some extent by the mold device 10, is inserted into the cavity 23 in such a state. At this time, the temperature of the intermediate product W2 has increased to 200°C or more due to the molding in the previous process, so when the intermediate product W2 is immersed in the lubricant filled in the cavity 23, the lubricant reacts as described above. A solid lubricant film is generated on the surface of the intermediate product W2. The intermediate product W2 with the solid lubricant film formed on its surface is pushed into the cavity 23 by the bunch 22, and as shown in FIG.
) An intermediate product W3 as shown in FIG.

In addition, during molding by the mold device 20, the lubricant supplied into the cavity 23 is absorbed into the cavity 23 because the upper end of the cavity 23 is closed by the large diameter portion of the intermediate product W2.
The pressure of the lubricant in the cavity 23 increases as the intermediate product W2 is forced downward by the bunch 22. When the pressure of the lubricant exceeds a certain value, the relief valve 48 opens and the cavity 23
The lubricant in the discharge passage 271. is maintained at a constant pressure. It is returned into the tank 41 via the discharge vibe 43.

During forging, the lubricant is trapped inside the cavity until it exceeds a certain pressure, so the hydrostatic pressure effect causes the middle cylinder part W
The lubricant is sufficiently distributed over the entire surface of 2.

In this way, once forging by the mold device 20 is completed, forging by the mold device 30 is started before age hardening after forming becomes noticeable, as described above.

Incidentally, in the molding by the mold device 30, the spline is also formed at the same time as the drawing, to obtain the countershaft W4 shown in FIG. 2(D).

Incidentally, in the embodiment, the forming of the countershaft has been described, but the present invention can also be applied to the case where a constant velocity joint is manufactured through the steps shown in FIG.

(Effects of the Invention) As explained above, according to the present invention, when performing a plurality of cold forging processes in succession, a heat-reactive lubricant is filled into the mold cavity in the second and subsequent forging processes. Since the material is kept in the mold for a long period of time, a lubricating film is formed on the surface of the material simply by introducing it into the cavity, so that the next molding can be performed before age hardening after molding begins.

Therefore, it is possible to eliminate intermediate IA processes such as forming a lubricating film or performing annealing for each forming process as in the past, and work efficiency is greatly improved.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a vertical forming press machine that carries out the method of the present invention, Figures 2 (A) to (D) are diagrams showing the process of shape change from a billet to a product, and Figure 3 is a diagram showing the change in shape from a billet to a product. Figure 4 is a graph showing the relationship between temperature and friction coefficient. Figure 5 is a graph showing the relationship between elapsed time after molding and the temperature and hardness of the material. Figure 6 is a graph showing the relationship between temperature and friction coefficient. It is a figure which shows another Example. In addition, in the drawing, 10, 20.30 are mold devices, 13.23
．． 33 is a cavity, 26.36 is a lubricant supply path, 2
7.37 is a lubricant discharge path, and 40 is a lubricant supply/discharge device. Patent applicant: Agent for Honda Motor Co., Ltd.
Patent Attorney Part 2 1) Part 1 Patent Attorney
Kuni Ohashi, Patent Attorney
Udo Koyama Patent Attorney No
1) Shigeru Diagram 2 (A) (B) (c) (D)

Claims (2)

[Claims] (1) In a continuous cold forming method consisting of multiple forging processes, the first forging process involves forming a material with a chemical conversion film formed on its surface, and the subsequent forging process involves pre-filling the mold cavity with a heat-reactive liquid. Filled with lubricant, this liquid lubricant is brought into contact with the material whose temperature has increased due to the previous forming process, and the material is formed with a lubricant film formed on the surface of the material.Furthermore, the second and subsequent forging processes are performed using the forming process in the previous process. A continuous cold forming method characterized in that the cold forming process is carried out before subsequent age hardening begins. (2) The continuous cold forming method according to claim 1, wherein the thermally reactive liquid lubricant is made by adding a calcium additive and a sulfurized oil to naphthenic base oil. (3) The continuous cold forming method according to claim 1, wherein the time between the second and subsequent forging steps and the preceding step is within 18 seconds.