JP6115313B2 - Production line and production method for differential thickness steel plate products - Google Patents

Description

  The present invention relates to a production line and a production method for producing a differential steel plate product using a warm forging device.

  In recent years, weight reduction has been promoted in order to improve the fuel efficiency of automobiles. One way to reduce the weight is to improve the metal material constituting the body of the automobile. Specifically, in addition to the method of changing the steel material of the automobile body component to a thin and high strength steel material, or the method of changing the material of the component member to an aluminum alloy or magnesium alloy having a lighter specific gravity than steel, For example, there may be mentioned a method of imparting a thickness distribution to the constituent members so as to reduce the thickness of the constituent members to the limit that can ensure the performance.

  Among these, regarding the method of attaching the plate thickness distribution to the constituent members, the steel plate provided with the plate thickness distribution is generally called a differential thickness steel plate. There are various types of differential thickness steel plates depending on the application. For example, a material having a length of about 2000 mm and a width of about 500 mm, a plate thickness of 2 mm from both ends in the longitudinal direction to 300 mm, and a central portion having a plate thickness of 1.6 mm (plate thickness 2 level symmetrical type), or conversely in the longitudinal direction From the both ends to 300 mm, a plate type with a plate thickness of 1.8 mm and a central portion with a plate thickness of 2.0 mm (plate thickness 2 level symmetrical type) can be mentioned. Other examples include those in which the plate thickness is changed in a taper shape in the longitudinal direction, and those having a multi-level thickness or a symmetric or asymmetric type.

  As an apparatus for producing such a differential thickness steel sheet, for example, an apparatus that uses a rolling mill to operate the work roll reduction position (roll gap) during rolling can be considered (for example, Patent Document 1). In particular, in the rolling apparatus described in Patent Document 1, a load cell for detecting a rolling load is provided, and the rolling load detected by the load cell is reduced so as to be a required load calculated based on a required plate thickness. The device is controlled. In addition, in this specification, the apparatus which manufactures a differential thickness steel plate using a rolling mill is especially called "the manufacturing apparatus of the differential thickness steel plate by a rolling method."

  By the way, as an apparatus for producing a differential thickness steel sheet by a rolling method, a sheet thickness detection device provided on the delivery side of the rolling mill detects the thickness of the material to be rolled on the delivery side of the rolling mill, and a reduction position based on the detected value. It is possible to control this. However, in the differential thickness steel plate, the length in the rolling direction of the portion where the plate thickness is constant is generally short. For this reason, since there is a certain distance from the roll bite outlet to the plate thickness detecting device, a dead time occurs, and this device cannot perform appropriate plate thickness control.

  Also, as another manufacturing equipment for differential thickness steel sheets by rolling method, the plate thickness and speed of the material to be rolled on the entrance side of the rolling mill and the speed of the material to be rolled on the exit side of the rolling mill are detected, and the constant mass flow is used. It is also possible to estimate the thickness of the material to be rolled on the rolling mill exit side and control the reduction position based on the estimated value. However, it is difficult to install a device for detecting the speed of the material to be rolled on the exit side of the rolling mill in the immediate vicinity of the roll bite outlet even in the device using the constant mass flow rule, and there is a waste time, Since an estimation error occurs in the thickness of the material to be rolled due to the widening of the width, appropriate thickness control cannot be performed even with this apparatus. In addition, this apparatus requires a plurality of speed detection devices and plate thickness detection devices, which increases the equipment cost.

  In consideration of such a situation, apparatuses using a preset rolling method and an absolute value rolling method have been proposed as apparatuses for producing a differential thickness steel sheet by a rolling method. In the preset rolling method, the relationship between the rolling position of the rolling mill and the thickness of the material to be rolled that has been rolled by the rolling mill is obtained in advance by experiments or numerical calculations. During rolling, the rolling length, which is the length in the rolling direction of the part already rolled by the rolling mill, of the material being rolled by the rolling mill is calculated based on the rotation speed of the work roll, and in advance The reduction position is controlled so that the plate thickness pattern of the material to be rolled becomes the target plate thickness pattern based on the relationship between the calculated reduction position and the thickness after rolling, and the calculated rolling length.

  In the absolute value rolling method, the relationship between the rolling load and the deformation of the rolling mill (deformation characteristics of the rolling mill) is obtained in advance by experiments, numerical calculations, and the like. During rolling, the rolling length is calculated based on the rotation speed of the work roll, and the rolling load is detected at the roll bite outlet on the basis of the deformation characteristics of the rolling mill determined in advance and the detected rolling load. The thickness of the material to be rolled is estimated. Then, the reduction position is controlled so that the thickness estimated in this way becomes the target thickness based on the calculated rolling length.

JP-A-3-281010

  By the way, as described above, in the apparatus for producing a differential thickness steel sheet by the rolling method, the thickness of the material to be rolled is basically changed by changing the rolling position of the rolling mill. When such an apparatus is used, it is necessary to increase the control speed of the reduction position in order to increase the production speed (productivity) of the differential thickness steel sheet. In general, since the hydraulic pressure reduction device has high responsiveness, it is essential to install the hydraulic pressure reduction device in order to increase the control speed of the reduction position. However, since the hydraulic reduction device is expensive, the equipment cost increases, and as a result, the manufacturing cost of the differential thickness steel sheet increases. For this reason, the manufacturing apparatus which manufactures a differential thickness steel plate efficiently without using a hydraulic reduction apparatus, ie, using methods other than a rolling method, suppressing manufacturing cost is desired.

  Then, in view of the said subject, the objective of this invention is providing the manufacturing apparatus which manufactures a differential thickness steel plate product efficiently, suppressing manufacturing cost using methods other than a rolling method.

  In order to solve the above problems, the present inventors have conducted intensive research, can manufacture a differential thickness steel sheet by warm forging instead of the rolling method, and when performing warm press forming after warm forging. Is able to efficiently use thermal energy by performing warm pressing at a high temperature of the differential thickness steel plate after warm forging, resulting in efficient production of the differential thickness steel plate product at a reduced cost. It was found that can be manufactured.

This invention was made | formed based on the said knowledge, and the summary is as follows.
(1) A heating device for heating a workpiece steel plate, a forging device forging a differential thickness steel plate from the workpiece steel plate heated by the heating device, and the outer shape of the differential pressure steel plate forged by the forging device has a predetermined shape A punching device for punching, a warm press device for producing a differential steel plate product by warm press forming a differential steel plate forged by the forging device, and the warm press device from the heating device In the production line of the differential thickness steel plate product, comprising the conveying device configured to convey a plurality of rollers up to the workpiece steel plate, from the upstream side toward the downstream side, the heating device, the forging device, the punching Insulation covering the conveying path between the heating device and the forging device, between the forging device and the punching device, and between the punching device and the warm pressing device It is provided, the different thickness steel sheet product of the production line.
( 2 ) A heating step for heating the processed steel plate, a forging step for forging a differential thickness steel plate from the processed steel plate heated in the heating step, and the outer shape of the differential thickness steel plate forged by the forging step has a predetermined shape A punching process for punching out, a warm press process for producing a differential steel sheet product by warm press forming the differential steel sheet forged in the forging process, and the warm pressing process from the heating process. In the manufacturing method of the differential thickness steel sheet product, including the transporting process configured by a plurality of rollers for transporting the steel plate to be processed , from the upstream side toward the downstream side, the heating step, the forging step, the punching step The heat insulating material is disposed in the order of the warm pressing process and covers the conveying process between the heating process and the forging process, between the forging process and the punching process, and between the punching process and the warm pressing process. Vignetting was, the different thickness steel sheet product manufacturing method of.
( 3 ) The manufacturing method of the differential thickness steel plate product according to (2), wherein the differential thickness steel plate is not heated between the forging step and the warm pressing step.

  According to the apparatus for manufacturing a differential thickness steel sheet of the present invention, there is provided a manufacturing apparatus for efficiently manufacturing a differential thickness steel sheet while suppressing the manufacturing cost by using a method other than the rolling method.

FIG. 1 is a diagram schematically showing a production line for a differential thickness steel sheet according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a manufactured differential thickness steel plate. FIG. 3 is a diagram schematically showing the configuration of the forging device. FIG. 4 is a perspective view schematically showing an example of a differential thickness steel plate product manufactured by press forming a differential thickness steel plate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are assigned to similar components.

FIG. 1 is a diagram schematically showing a production line 1 for a differential thickness steel sheet having a thickness difference in the rolling direction according to an embodiment of the present invention. As shown in FIG. 1, the production line 1 includes a heating device 10 that heats a workpiece (steel plate to be processed) W, a forging device 20 that is disposed on the downstream side of the heating device 10 in the production line 1, and a forging device 20. A punching device 40 disposed on the downstream side of the punching device and a warm press device 30 disposed on the downstream side of the punching device 40 are provided.
In the production line 1 of this embodiment, heat insulation covers the conveyance path between the heating device 10 and the forging device 20, between the forging device 20 and the punching device 40, and between the punching device 40 and the warm press device 30. Materials are provided.
As can be seen from FIG. 1, a heat insulating material 61 is provided between the heating device 10 and the forging device 20 so as to cover the conveyance path of the workpiece W (that is, the path on the plurality of rollers 51 of the conveyance device 50). Thereby, it is suppressed that the temperature of the workpiece | work W falls between the heating apparatus 10 and the forge apparatus 20. FIG. In addition, in this embodiment, although the heating apparatus 10 and the forge apparatus 20 are comprised as a different body, these apparatuses 10 and 20 may be comprised as an integrated apparatus.
Further, as can be seen from FIG. 1, between the forging device 20 and the punching device 40 and between the punching device 40 and the warm press device 30, heat insulating materials 62 and 63 are provided so as to cover the conveyance path of the workpiece W. Each is provided. Thereby, it can suppress that the temperature of the workpiece | work W falls between the forging apparatus 20 and the warm press apparatus 30. FIG. For this reason, the heat energy applied to the workpiece W by the heating device 10 can be used more efficiently.

  The production line 1 also includes a transport device 50 that transports the workpiece W in the order of the heating device 10, the forging device 20, the punching device 40, and the warm press device 30. As can be seen from FIG. 1, in the present embodiment, the conveying device 50 includes a plurality of rollers 51 arranged in a line in parallel with each other. Each roller 51 is rotationally driven in the same direction by a driving device (not shown), whereby the work W arranged on the conveying device 50 is conveyed in the direction indicated by the arrow in FIG. Note that not all of the rollers 51 of the conveying device 50 may be driven to rotate, and some of the rollers 51 may be configured to freely rotate.

  The heating device 10 heats the workpiece W to a target temperature that is equal to or higher than the recrystallization temperature (for example, 1100 to 1250 ° C.). In the present embodiment, the heating device 10 is a continuous heating furnace that performs heating by burning fuel. Therefore, the workpiece W is continuously heated while being conveyed on the conveying device 50 in the heating device 10, and the temperature gradually rises. The workpiece W at room temperature at the inlet of the heating device 10 is heated to the target temperature before reaching the outlet of the heating device 10. Note that the heating apparatus 10 is not necessarily a heating furnace, and may be an energizing heating apparatus that performs heating by energizing heating or an induction heating apparatus that performs heating by induction heating.

  By the way, usually, a very large force is required to plastically deform a metal material. For example, when steel material is forged warmly, depending on the size of the forged part, usually, a pressing force of several hundred tons to several thousand tons is required. Also, in order to withstand this force, the forging device itself is made rugged and its weight is several tens of tons or more.

  Here, the deformation resistance corresponding to the applied pressure per unit area decreases as the temperature rises. For example, in JIS steel SCr420, heating at 800 ° C. reduces the room temperature to 1/2, and heating at 1000 ° C. reduces the room temperature to 1 / 3. Decrease to about 1/6 of room temperature by heating at 1200 ° C. Therefore, when parts having the same shape are forged at different temperatures, forging at a high temperature can be performed with less pressure, which is advantageous for downsizing of the forging apparatus.

  Therefore, in the present invention, forging is performed after the work (steel plate to be processed) W is heated in advance, thereby reducing the pressure required for forging. Thereby, the pressurization force (rolling force) required by the rolling device of the forging device 20 can be made small, and therefore the forging device 20 can be made inexpensive.

  Next, the forging device 20 will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram illustrating an example of the differential thickness steel plate manufactured by the forging device 20. FIG. 3 is a diagram schematically showing the configuration of the forging device 20 of the present embodiment. As shown in FIG. 3, the forging device 20 includes a main body frame 21, a reduction device 22, a slider 23, an upper die 24, and a lower die 25. In the example shown in FIG. 2, the work is conveyed in a direction perpendicular to the paper surface of FIG.

  The reduction device 22 is an electric reduction device and is fixed to the upper part of the main body frame 21. The slider 23 is disposed so as to be slidable with respect to the main body frame 21 and is connected to the reduction device 22. The slider 23 is slid upward and downward with respect to the main body frame 21 in accordance with the operation of the reduction device 22. The upper mold 24 is fixed to the lower surface of the slider 23. Therefore, the upper mold 24 functions as a movable mold that can be moved upward and downward as the slider 23 moves. On the other hand, the lower mold 25 is fixed to the main body frame 21 and functions as a fixed mold.

  Thus, the upper mold 24 is movable relative to the lower mold 25. And when the workpiece | work W is arrange | positioned between these metal mold | die 24,25, the forge of the workpiece | work W is performed by moving the upper metal mold | die 24 so that these metal mold | die 24,25 may be closed.

  In particular, in the example shown in FIG. 3, a plurality of steps are provided on the press surfaces of the upper mold 24 and the lower mold 25. As a result, when forging is performed by the forging device 20, the differential thickness steel sheet shown in FIG. 2 is manufactured. In the example shown in FIGS. 1 and 3, the differential thickness steel plate is manufactured so that the thickness difference is formed in a direction perpendicular to the moving direction of the workpiece W. However, the difference-thickness steel plate may be manufactured so that a plate thickness difference is formed in the traveling direction of the workpiece W, or the plate thickness difference is formed in the traveling direction of the workpiece W and the direction perpendicular to the traveling direction. Thus, a differential thickness steel plate may be manufactured.

  The punching device 40 is a punching device that punches the workpiece W so that the outer shape of the workpiece W becomes a predetermined shape. When the workpiece W is forged by the forging device 20 disposed upstream of the punching device 40, the workpiece W has an outer shape different from that before entering the forging device 20. For this reason, punching is performed by the punching device 40 in order to make the outer shape of the workpiece W suitable for press molding in the warm pressing device 30 before the workpiece W is conveyed into the warm pressing device 30.

  Next, similarly to the forging device 20, the warm press device 30 includes a reduction device (not shown), a slider (not shown), an upper die 34, and a lower die 35. In the warm press device 30, by moving the upper die 34 toward the lower die 35 in a state where the workpiece W (different thickness steel plate forged by the forging device 20) is arranged on the lower die 35, Press forming of the workpiece W is performed. As a result, the difference thickness steel plate product of a desired shape is manufactured by the warm press apparatus 30. Specifically, for example, the differential thickness steel plate product as shown in FIG. 4 is manufactured by press forming the differential thickness steel plate as shown in FIG. In the example shown in FIG. 4, bending is performed as press molding.

  Here, in the forging in the forging device 20, the plate thickness of the workpiece W changes greatly. Therefore, it can be said that the forging in the forging apparatus 20 is performed with a change in the plate thickness. On the other hand, in the press molding in the warm press apparatus 30, the plate thickness of the workpiece W hardly changes. Therefore, it can be said that the press forming in the warm press apparatus 30 is performed with hardly any change in the plate thickness. Specifically, in the press molding in the warm press apparatus 30, the plate material is bent mainly in accordance with the target shape.

  In the present embodiment, the warm press device 30 is provided close to the forging device 20. For this reason, the workpiece W carried out from the forging device 20 is carried into the warm press device 30 while its temperature is hardly lowered, that is, at a high temperature. For this reason, the forging in the forging device 20 and the pressing by the warm press device 30 can be performed twice only by heating once with the heating device 10. Therefore, the heat energy applied to the workpiece W by the heating device 10 can be used efficiently.

  For this reason, in this embodiment, the heating apparatus which heats the workpiece | work W is not provided between the forge apparatus 20 and the warm press apparatus 30, Therefore Forging by the forge apparatus 20 and warm press by a warm press apparatus, The work W is not heated between the two.

  In this embodiment, before the temperature of the workpiece W forged by the forging device 20 reaches the normal temperature, preferably before the temperature of the workpiece W drops below the temperature required for the warm pressing, the warm pressing device. It is sufficient that warm press formation is performed by 30. As long as warm press molding is performed in this way, thermal energy can be used more efficiently than warm press molding of a workpiece W at room temperature.

DESCRIPTION OF SYMBOLS 1 Production line 10 Heating device 20 Forging device 21 Main body frame 22 Reduction device 23 Slider 24 Upper die 25 Lower die 30 Warm press device 34 Upper die 35 Lower die 40 Punching device 50 Conveying device 51 Roller 61 Heat insulating material 62 Insulation W Metal strip

Claims (3)

A heating device that heats the workpiece steel plate, a forging device that forges the differential thickness steel plate from the workpiece steel plate heated by the heating device, and the outer shape of the differential pressure steel plate that is forged by the forging device is a predetermined shape. A punching device for punching, a warm press device for producing a differential steel plate product by warm press-forming a differential steel plate forged by the forging device, and processing from the heating device to the warm press device In a production line for differential thickness steel plate products, comprising a conveying device composed of a plurality of rollers for conveying a steel plate,
From the upstream side toward the downstream side, the heating device, the forging device, the punching device, and the warm press device are arranged in this order, between the heating device and the forging device, between the forging device and the punching device, and A production line for differential thickness steel plate products provided with a heat insulating material covering the conveyance path between the punching device and the warm press device . A heating step of heating the steel plate to be processed, a forging step of forging a differential thickness steel plate from the steel plate to be processed heated in the heating step, and an outer shape of the differential thickness steel plate forged by the forging step so as to have a predetermined shape A punching process for punching in, a warm pressing process for producing a differential steel sheet product by warm press forming the differential steel sheet forged in the forging process, and processing from the heating process to the warm pressing process. In the manufacturing method of the differential thickness steel plate product, including a transport process composed of a plurality of rollers for transporting the steel plate,
From the upstream side toward the downstream side, the heating step, the forging step, the punching step, the warm pressing step are arranged in this order, between the heating step and the forging step, between the forging step and the punching step, and The manufacturing method of a differential thickness steel plate product provided with the heat insulating material which covers the conveyance process between a punching process and a warm press process . The method for producing a differential steel sheet product according to claim 2 , wherein the heating of the differential steel sheet is not performed between the forging step and the warm pressing step.

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