JPH0450081B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rolling split molding method. The rolling split molding method is a method in which a material is rolled by a rolling mill, and the rolled material is divided into a plurality of products on the exit side of the rolling mill using a tool having a knife edge shape.

A processing method similar to the method of the present invention is a rolling extrusion method.

The rolling extrusion method is a method in which a die is installed on the exit side of the roll gap of a rolling mill, and the material is pressed into the die while being rolled down by a work roll to obtain a finished product.

The advantages and disadvantages of traditional extrusion methods are as follows.

(1) Large deformation in one process (section reduction ratio 0.9 or more)
In addition, tubes, rods, plates, etc. with complex cross sections can be processed from a single material.

(2) Even brittle materials that are difficult to process by normal rolling can be extruded without cracking.

(3) Processing can be performed in a few seconds, which is advantageous even for materials with a narrow processing temperature range.

(4) Since high pressures of 20 to 120 ^kgf / ^mm2 are applied to tools and machines per unit area, expensive tools and machines with high rigidity and strength are required. Also, tool wear is severe.

(5) It is necessary to seal the material during processing, which limits the volume of material that can be extruded at one time, and the work is intermittent and slow, resulting in low productivity.

Therefore, in order to specifically overcome the drawback (5), the conform method and the extra rolling method (rolling extrusion method) have been developed, in which long materials are continuously extruded like normal rolling. Since the principles of both are similar, we will explain the latter here.

The extra rolling method is a combination of rolling and extrusion, in which the material (plate, bar, wire) is drawn in by rolls, as shown in Figures 1 to 4.
The cross section can be reduced. There is an extrusion die at the exit of the nip between the rolls, and the material is extruded from this mouth.
The pressure required for extrusion is provided by friction from the roll surfaces. Therefore, the pressure is only atmospheric pressure on the entrance side of the roll gap, but increases as it goes further forward, and the material is drawn from the outside toward the die one after another, making continuous extrusion possible.

Continuous extrusion is expected to have a wider range of applications in the future, taking advantage of its advantages of being suitable for high-mix, low-volume production as mentioned above, and of being able to process difficult materials (including powders) into difficult shapes. However, on the other hand, there are major problems, and development is impossible unless these problems are resolved.
This is a problem with the overhang (also called flash) between the roll and the die. This is an unavoidable drawback of conventional rolling extrusion methods. In other words, the high pressure necessary for extrusion is generated at the die entrance;
The material is thinly inserted between the roll and the die in sections EE and FF in Fig. 1 due to two points: and the rolls are rotating and drawing in the material, and the material flows out continuously. This results in very large plastic deformation being imparted to the material between the roll and the die, requiring excessive extrusion force, and furthermore causing a decline in material yield and quality. The existence of such a seepage phenomenon is the fundamental reason why the rolling extrusion method has not been industrially successful.

Attempts have also been made to prevent extrusion by applying hydrostatic pressure between the die and the roll from behind the die, but I have not heard of any success so far. Even if it were successful, it would be economically disadvantageous because it would require special equipment such as a high-pressure seal and a pressure-applying device.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel roll extrusion method that can eliminate the drawbacks of the conventional roll extrusion method and improve yield and quality.

The biggest drawback of the conventional roll extrusion method is the material being squeezed out between the roll and the die, and this is the main factor that has hindered industrialization. In the present invention, the rolling extrusion method has been brought to success by changing the shipping process by converting this unavoidable material protrusion into a finished product.

The rolling split forming method of the present invention involves rolling mill rolls and
A tool whose tip has a knife edge shape is installed in the gap, and the material is rolled down by a work roll, and the material is pressed against the tip of the tool and divided into a plurality of products. It is characterized by producing a finished product.

Here, the inside of the roll gap refers to the line between the point where the material leaves the roll after rolling (points a' and a' in Figure 5) and the center point of the cross section of the upper and lower rolls (YY in Figure 5). The reason why the tool is provided downstream from this center point is that if the tool is provided upstream from this point, the force for pressing the material against the tool will be insufficient, making it impossible to perform split molding.

In the above method, it is preferable that the work roll is provided with a stepped portion and that the roll is movable in the axial direction so that the width of the roll gap can be adjusted.

Furthermore, in the above method, it is preferable to provide a material pushing device on the entry side of the rolling mill to facilitate extrusion of the material.

Next, specific examples of the rolling split forming method of the present invention will be described with reference to the drawings. For the sake of convenience, the following description will be made regarding the material and the finished product in the form of a strip, but other shapes such as a rod shape and a wire shape may also be included.

As shown in FIG. 5, in the rolling split forming method of the present invention, a tool 3 with a knife-edge tip is installed between the gap of the work roll 2 on the exit side of the rolling mill 1, and a material 4 is placed at the tip of the tool. A plurality of products 41, 42 are obtained by pressing. In this case, the material 4 whose cross section has been reduced by being drawn in by the roll 2 is divided into upper and lower parts by the tool 3, and each part is sent out from between the roll and the tool to form finished products 41 and 42. That is,
This corresponds to creating a finished product by increasing the thickness of the conventional flash with the largest defect.

If we compare the same cross-section reduction ratio (ratio of tool entry side thickness to tool exit side total thickness) with the conventional model, the plate thickness has been reduced to a fraction of that, and a stronger reduction than before can be achieved with the same extrusion force. Moreover, it has become an innovative method that does not cause the bulging phenomenon.

In the conventional method shown in Figures 1 and 2, when the material width on the entry side was changed, the upper and lower rolls had to be replaced according to the sheet width, which was inefficient.
As shown in the figure, work roll 2 is a stepped roll,
By being configured to be shiftable in the axial direction, it is possible to easily accommodate changes in the width of the material, and it is only necessary to replace the delivery tool.

When the cross-section reduction ratio is relatively small, the pressure necessary for extrusion can be obtained only by the friction of the rolling rolls, but if the cross-section reduction ratio becomes extremely large, extrusion cannot be achieved only by the friction of the rolls, so as shown in Figure 8. As shown, it becomes necessary to provide an endless track type pushing device 5 on the work roll entry side. In addition to the endless track system shown in FIG. 8, a rolling roll (not shown) may be installed on the upstream side to apply compressive force.
In any case, if the area reduction ratio becomes extremely large and the extrusion pressure is insufficient due to the frictional force of the rolls alone, it is necessary to provide some type of pushing device 5 on the roll entry side.

(Example) First, as a comparative example, the following rolling extrusion was performed by a conventional method. Diameter 240mm in Figures 1 and 2
Rolled material with rolls of 10mm thick x 100mm wide
The lead material was rolled to a thickness of 5 mm and then rolled.
Thickness is determined using the die shown in Figure 3 A installed on the exit side of the gap.
Extruded to 2.8mm. Although it was possible to extrude without backward pushing force, flashing occurred on the upper and lower surfaces, and when the rolls were slightly worn, the thickness of the flashing suddenly increased.

Therefore, the tool 3 shown in FIG. 5 was installed slightly offset to the downstream side from the roll gap center, and when extruded, two plates with a thickness of 1.2 mm were formed separately. At this time, both rolling load and torque were reduced by about 30 to 40% compared to the comparative example.

Furthermore, when the tool offset amount was increased using the same method, two plates with a thickness of 1.0 mm were formed separately.

Setting the vertical position of the tool and restraining its displacement in the vertical direction are one of the key points of this rolling split forming method. We also confirmed that the product thickness can be adjusted using both roll gap (vertical relative position) adjustment and tool offset adjustment. It was also confirmed that extrusion is easier when the tool is offset downstream from the roll center line. This is because the extrusion pressure due to roll friction increases due to offset.

Next, using the device shown in Figure 5, the thickness of the 10 mm thick lead material was
When I tried to mold two sheets of 0.5mm and 0.5mm separately, the loin slipped and it was impossible to extrude it, so when I applied pushing force from the rear as shown in Figure 8, smooth extrusion was possible. It became. Note that the extrusion pressure can be increased by tightening the roll gap. Once it reaches a certain point, the material will no longer be absorbed.

Furthermore, the roll shape of the rolling mill was changed as shown in Figure 7, and the sheet thickness was 10 mm and the sheet width was changed to 70 mm, 100 mm, and 130 mm, and the rolls were shifted accordingly. By simply reducing the thickness, two 1 mm thick products were molded separately.

Next, it was confirmed that a plate with a special cross section having a convex portion on one side as shown in FIG. 8A can be extruded by making the tool shape partially stepped.

Furthermore, when grooves were formed on the roll side, it became possible to extrude a plate with a special cross section having convex portions on both the upper and lower sides as shown in FIG. 8B. Generally speaking, it is desirable to use flat rolls as rolling rolls, but this requires restraint in the width direction. Therefore, as shown in Fig. 9, a tool that restrained the deformation of the material in the width direction was inserted, a lead material of 10 mm thickness x 100 mm width was rolled to a thickness of 5 mm, and two products of 1 mm thickness x were extruded.
Results similar to those of the example shown in FIG. 6 were obtained.

Next, an extrusion experiment was conducted with the restraint on width direction deformation removed, and it was confirmed that extrusion was possible without any problems, although the width of the material increased. This method makes it very easy to support and cool the tool and is inexpensive in terms of equipment.

The experimental results have been described above using lead materials, but similar results were obtained with Al plates (room temperature, hot work), hot work steel, etc. Moreover, it could be applied not only to plate materials but also to round bars and shaped steel.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a conventional rolling extrusion method. FIG. 2 is a front view of a conventional stepped roll. FIG. 3 is a perspective view of various dies used in the conventional rolling extrusion method.
FIG. 4 is a longitudinal sectional view taken from the - line of A in FIG. FIG. 5 is a schematic explanatory diagram of the rolling split molding method of the present invention. FIG. 6 is a front view of a stepped roll used in the rolling division forming method of the present invention. FIG. 7 is a schematic explanatory diagram of the rolling split molding method of the present invention provided with a material pushing device.
FIG. 8 is a cross-sectional view of a deformed product formed by the rolling split forming method of the present invention. FIG. 9 is a longitudinal sectional view showing a deforming tool used in the rolling split forming method of the present invention. 1: Rolling mill, 2: Work roll, 3: Tool,
4: Material, 5: Pushing device, 41, 42, 43:
Finished product.

Claims (1)

[Claims] 1. A tool with a knife-edge tip is installed in the roll gap of a rolling mill, and the material is rolled down by a work roll, and the material is pressed against the tip of the tool to form a plurality of products. 1. A rolling split-forming method characterized by split-forming and sending the product between a roll and the tool. 2. The rolling according to claim 1, characterized in that the work roll is provided with a stepped portion and the roll is configured to be movable in the axial direction, so that the width of the roll gap can be freely adjusted. Split molding method. 3. The rolling split-forming method according to claim 1, characterized in that a material pushing device is provided on the entry side of the rolling mill to facilitate pushing of the material.