JPH0475106B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for forging a long forged product in hot forging. The present invention relates to a forging method in which preforming is performed and then final forming is performed using a forging press.

[Conventional technology and its problems] Conventionally, in order to increase the productivity and yield of die forged products that have different cross-sectional shapes in the longitudinal direction, preforming has been performed in which raw materials are compressed and stretched while reducing the cross-sectional area. It is being said. The preformed material is then sent to a forging press for final forming, so
It is common practice to combine a preformer with a forging press.

For example, forging rolls are used as pre-forming for die forging, with the aim of increasing productivity and improving the yield of billets (raw materials), which is the core of measures to reduce the cost of forged products.

By the way, in such a forging roll, the lower the number of passes, the lower the temperature drop of the billet, making it easier to form forge in the next step, but the amount that can be reduced by one pass depends on the amount before and after processing. It is said that the cross-sectional area ratio is usually less than 1.60. Furthermore, if the cross-sectional reduction rate of the billet is to be made as large as possible, the load applied to the roll shaft will also increase accordingly, and a large-capacity machine will be required.

Under these constraints, in conventional preforming, for example, when forming a connecting rod for internal combustion engines (for example, a two-cavity type using a normal forged roll), four to five passes are required. For this purpose, forging rolls can be lined up in series for the required number of passes, and each pass passes the next forging roll convoluted roll, or a single forging roll can be used and moved laterally for each pass. The use of a manipulator method that allows

However, in the former case, the cycle time is shortened, but the equipment cost and lining cost are high; in the latter case, although the equipment cost is low, it is necessary to transport the billet laterally with a manipulator for each process, and forging rolls are used. Preforming takes a long time compared to final forming using a forging press, resulting in longer cycle times, lowering the operating rate of the entire line and reducing productivity. Therefore, as shown in the layout diagram of Fig. 4, two forging rolls 1 and 1 are installed together, and each forging roll 1 has a
Pass forming is performed, and then each billet is alternately subjected to final forming using one forging machine 2 in order to shorten cycle time as much as possible and improve material yield.

To explain this in detail, in the forging process diagram in Fig. 5, a round bar-shaped billet 3 is placed on the first forging roll 1.
When the billet 3 is inserted and passed in one pass, the two extended portions 3' and 3' (corresponding to the connecting rod shaft portion of the connecting rod) of the billet 3 are compressed and formed into an elliptical cross-section.

As a result of this compression molding, the cross-sectional area of the billet 3 is somewhat reduced where the cross-section becomes elliptical, so that the overall length of the billet 3 becomes longer.

Next, in two passes, the billet 3 is reversed 90 degrees and inserted into and passed through the forging roll 1 to form the parts having an elliptical cross section (extended parts 3',
3') is compressed with a roll. The elongated portions 3', 3', which have an elliptical cross-section, are elongated in the axial direction while decreasing their cross-sectional area to form a circular shape (the cross-section of the billet 3 becomes circular because of the roll cross-section of the forging roll 1). (This is because the groove is semicircular.) Returning to the above, billet 3 has a length L1 including the length stretched in the first pass.
An elongation step 15 is performed in which the image is elongated by the same amount.

Next, three or four passes of forming are performed in the same manner as described above, and the billet 3 stretched in the two passes is further stretched by a length L2 (stretching step 16) to form a preformed material 4. The preformed material 4 is sent to the forging press 2 via the selective feeding device 13, and a crushing step 10 is performed.
and finishing step 12 is performed. (Pre-forming in which the billet 3 described above is compressed and formed into an elliptical cross-section, and the cross-sectional area of the elliptical portion is reduced while being stretched in the axial direction to make the cross-section circular is, for example, Mold forging May 31, 1982 Published by New Japan Casting and Forging Association P120-127 3.1.4.8 Forging roll processing, cross roll processing, and forging technology course Mold design March 30, 1982 Published by Forging Technology Research Institute of
Listed on P435~4478.2 Forged Roll. ) However, the billet 3 is stretched or reduced in cross-section to match the cross-sectional shape of the forged product using two forging rolls 1, with at least four passes, and then forging is performed, in which forming accuracy is the main focus. press 2
Although it is relatively streamlined because it involves crushing and final forming, the equipment cost and lining cost are higher than the manipulator method that uses one forging roll.

Furthermore, since there is a selective feed device, there is a limit to the cycle time reduction, and there is a problem in that the cycle time of the entire line cannot be shortened.

Therefore, the present invention reduces the stretching process in the conventional preforming using forging rolls and uses only one forging roll. The above problem was solved by adding a step to reduce the difference in cycle time between preforming and final molding.
In other words, without reducing billet yield,
To provide a casting method that shortens cycle time while suppressing equipment costs.

[Means for Solving the Problems] In order to achieve the above goals, the method for forging a long forged product according to the present invention includes a stretching process, a crushing process, and a crushing process for a long forged product using a forging roll and a forging press. In a hot forging method that performs a finish forming step, the respective steps are distributed so that the forming times of the forging roll and the forging press are approximately the same, and after performing preliminary stretch forming with the forging roll, The elongated portion of the preformed material formed by the stretch forming or the elongated portion of the preformed material crushed and formed by the forging press is restrained in the width direction by a forging press, and only the elongated portion is is compressed, stretch forming is performed while forming an inclined burr by a burr forming part formed between the upper and lower molds, and then the molded member is finished formed by the forging press.

[Example] The structure of the present invention will be explained in detail below with reference to Examples.

FIG. 1 is a layout diagram corresponding to FIG. 4 showing a conventional example, and FIG. 2 is a forging process diagram corresponding to FIG. 5 showing a conventional example. Components that are the same as those in the prior art are designated by the same reference numerals and their explanations will be omitted.

This application shows an example of forming a connecting rod for use in an internal combustion engine, as in the past, using a conventional forging roll 1 for 4 to 5 times (including multiple stretching processes).
Instead of requiring several passes, one elongation process is performed using a forging press, and the processes are distributed so that each forming time is approximately the same.

That is, in this embodiment, in order to preform the billet 3 for one-heat forging, it is inserted and passed through one forging roll 1 as one pass. As a result, the elongated portions 3', 3' of the billet 3 are compressed and formed into an elliptical cross section.

With this forming, the overall length of the billet 3 becomes somewhat longer as explained in the prior art. Next, when the billet 3 is inserted and passed through the forging roll 1 in two passes while being reversed by 90 degrees, the portions 3' and 3', which have an elliptical cross-sectional area, are elongated in the axial direction while decreasing the cross-sectional area. The stretched parts 4', 4' return to their circular shape, and the billet 3
is extended by a length L1 including the length extended in the one pass. This is used as a preformed material 4 and sent to a forging press 2, where step 10 is first performed. In this crushing step 10, only the central large diameter portion of the preformed material 4 is compressed and crushed. At this time, the extended portions 5', 5' have a circular cross-section with a diameter φD (as shown in FIG. 3A) like the extended portions 4', 4'.

Next, in the same forging press 2, a stretching step 14 is performed in which only the stretched portions 5', 5' of the formed member 5 are stretched.
I do. At this time, as shown in FIG. 3B, the width direction of the elongated parts 5', 5' of the molded member 5 is restrained by the lower mold 9 and compressed by the upper mold 8, so that the elongated parts 5' of the molded member 5 are compressed. The cross-sectional shape of parts 5' and 5' is from φD (round) to T×H
Reduce the cross section (A1-A2) to a rectangle. That much,
The stretched portions 5', 5' of the molded member 5 are restrained in the width direction and compressed from the top and bottom as described above, so they are stretched by l in the axial direction, and during the 4th pass in the conventional preforming method. It is possible to extend it to the same extent.

For example, a preformed material 4 with a length of 145 mm can be expanded to 220 mm using a forging press, and a 158 mm length can be expanded to 240 mm. Note that the crushing step 10 and stretching step 14 of the preformed material 4 may be reversed.

Here, the present invention is not a closed forging system that is completely sealed, but a molded member 5 (preformed material 4).
The stretched parts 5', 5'(4',4') of the molded member 5 (preformed material 4) are compressed in the upper and lower molds 8, 9 and stretched in the axial direction while restrained by measuring in the width direction. End 5″,
5''(4'',4'') is made into a free state without being compressed by the upper and lower molds 8 and 9.

In other words, the mold is formed so that there is a gap between the ends 5'', 5''(4'',4'') of the molded member 5 (preformed material 4) and the upper and lower molds 8, 9. In other words, the upper and lower molds 8 and 9 in that part are eliminated so that the end portions 5'', 5''(4'',4'') can move freely in the axial direction.

The molds used in the crushing process 10 and the stretching process 14 have the same shape at the intermediate portion of the molded member 5.

Therefore, the crushing process 10 and the stretching process 14 in FIG.
As shown in the figure, there is no change in the shape of the end portion 5'' and the longitudinally intermediate portion of the molded member 5 formed in the crushing step 10 and the stretching step 14.

At the beginning of the stretching step 14, the stretched portions 5', 5' of the molded member 5 are compressed by the upper and lower molds 8, 9 while being constrained in the width direction. At that time, the extended portion 5',
The material at 5' is stretched axially and flows towards the ends and middle of the material. After that, after the middle part of the upper and lower molds 8, 9 (the part corresponding to the longitudinal middle part of the molding material 5) is filled with material, the material in the middle part is filled with the material in the end part along with the material in the extended parts 5', 5'. The stretching step 14 is performed by flowing in the direction.

In addition, burr forming parts 17 are provided on the upper and lower molds 8 and 9 of the extended portions 5', 5'(4',4'), and an appropriate angle α is applied to the burrs 11 that appear as excess metal. . Therefore, the upper and lower molds 8 and 9 are used to press the parts 5', 5'(4',
4′) is performed, but the upper mold 8 and lower mold 9
The clearance β between the sliding surface should be 0 to 0.05 mm, and
Upper mold 8 and lower mold 9 are placed on both sides of the lower surface of upper mold 8.
A burr forming portion 17 is provided, which is formed by having an appropriate thickness t and an appropriate length h, and forms an outwardly opened burr. Therefore, when stamping is performed in the next finish forming step 12, since the burr 11 is in an outwardly open shape, the burr 11 becomes a burr 7' during the finish forming and digs into the forged product 7. This means that scratches due to biting do not occur, and the load at the time of molding can be reduced, thereby extending the life of the mold. The burr 11 is included in the burr 7' formed around the forged product 7 in the final forming step 12. If the burr 11 is not formed, a defect will occur in the molded member 5 at the boundary line between the upper die 8 and the lower die 9, and the defect will dig into the forged product in the final forming process 12. There is a possibility of scratching the forged product.

Although the connecting rod has been described in this embodiment, it goes without saying that the present invention can be applied to any type of connecting rod having a linear long axis, such as a front axle.

In summary, since the present invention adopts the configuration described in the claims, the following effects are achieved.

[Effects of the invention] Since it has become possible to stretch and form long forged products using a forging press, it has become possible to freely set the process distribution between the forging roll and the forging press, and the forming time between the forging roll and the forging press can be reduced. They can be made substantially the same. As a result, the cycle time is shortened by 1.5 to 2 times, and the number of preforming machines installed can be reduced.
Equipment costs can be significantly reduced.

Since the number of preforming steps using forging rolls can be reduced, the temperature drop of the preformed material or billet in the preforming machine is reduced, and the life of the die of the forging press can also be extended.

Transportation of the preforming machine or billet is simplified, which in turn increases the operating efficiency of the entire line.

[Brief explanation of the drawing]

Figure 1 is a layout diagram of an embodiment of the present invention, Figure 2 is a layout diagram of an embodiment of the present invention.
The figure is a forging process diagram, Figure 3 A is a cross-sectional view of the billet after elongation, Figure 3 B is a cross-sectional view of the main part of the forging machine,
FIG. 4 shows a layout diagram of a conventional example, and FIG. 5 shows a forging process diagram of a conventional example. 1...Forging roll, 2...Forging press, 3...
billet, 4...preformed material, 4'...stretched member,
5, 6...Molded member, 10...Crushing step, 11...
...Flash, 12...Finish forming, 14, 15, 16
...Stretching process, 17...Flash forming section.

Claims (1)

[Claims] 1. In a hot forging method in which a long forged product is subjected to a stretching process, a crushing process, and a final forming process using a forging roll and a forging press, the forming times of the forging roll 1 and the forging press 2 are made to be approximately the same. , distributing the respective steps 14, 15, 10, 12,
After preliminary stretching 15 is performed by the forging roll 1, the stretched portion 4' of the preformed material formed by the stretching 15 is formed by the forging press 2, or by crushing by the forging press 2. The elongated portion 5' of the preformed material 5 is restrained in the width direction, and the elongated portion 4',
5' is compressed, stretch forming 14 is performed while forming an inclined burr 11 using a burr forming part 17 formed between the upper and lower molds, and then finishing forming 12 of the formed member 6 is performed using the forging press 2. A method for forging a long forged product.