JP5909725B2 - Method for specifying 3D dead zone shape in extrusion process - Google Patents

Description

  The present invention relates to a method for specifying a three-dimensional dead zone shape that causes bending during processing of a metal extruded product such as an aluminum alloy.

  Extruded products made of aluminum alloy that are lightweight, have excellent strength and corrosion resistance, and are highly recyclable are widely used for transportation equipment (Body of Shinkansen), electronic equipment components and building materials (aluminum sash).

  As shown in FIG. 14, the extrusion process is performed by pressing a cylindrical material 101 such as an aluminum alloy in a container 100 with a stem 102, and a die 110 having the same die hole 110 a as the product cross section provided at the end of the container 100. This is a processing method in which the cylindrical material 101 is plastically flowed (plasticity: a property of a substance that causes permanent deformation when pressurized).

  In general shape material extrusion processing, it is required to form a long variety of cross-sectional shape products straight in the extrusion direction. At the same time, in the case of hot extrusion of aluminum alloy, it is necessary to suppress the occurrence of surface recrystallization (beige skin pattern) appearing on the surface layer of the processed product.

  In the extrusion process, product defects such as bending and distortion occur in the product due to the uneven flow rate of the material at various locations of the die hole 110a of the die 110. As shown in FIG. 15, the cause of the occurrence is due to the difference in the outflow speed of the material near the outlet of the die hole 110a. The cause of the speed difference is the dead zone (from the start of processing to the end of processing in the work material). The region where the material does not move plastically and stays at all) The shape becomes asymmetrical (because it has undulations and becomes a three-dimensional shape). As shown in FIG. This is because of unevenness.

  In order to equalize the outflow speed, a flow guide 120 (plastic flow control plate, that is, a function of promoting or suppressing the material outflow speed) is generally installed between the cylindrical material 101 and the die 110 as shown in FIG. However, the design of the flow guide 120 depends on experience and intuition. In order to design a flow guide 120 that exhibits an appropriate plastic flow control function, the plastic flow in the vicinity of the die hole 110a is visualized three-dimensionally, the dead zone shape is accurately grasped, and the flow rate of the material is reduced. It is necessary to measure the uniform distribution with high accuracy. Further, since surface recrystallization is closely related to the material plastic flow during the extrusion process, it is necessary to grasp the velocity vector near the die hole 110a with high accuracy.

  In plastic processing of metals such as forging and extrusion processing, internal deformation information of complex-shaped parts that deform three-dimensionally is visualized by model experiments to evaluate machining process design, mold design, countermeasures for processing defects, etc. There is a method and apparatus related to a three-dimensional experimental simulation of plastic working aimed at studying (Patent Document 1). As a model material used for the simulation experiment, there is a model material that can reproduce deformation processes of various metal materials being processed while being a clay material (Patent Document 2).

  In addition, research to elucidate three-dimensional plastic flow, such as the identification of dead zones during metal extrusion (Non-Patent Document 1 to Non-Patent Document 5), and express plastic flow of extrusion only by a mathematical model. Many attempts have been made such as research (Non-Patent Document 6 to Non-Patent Document 8) for elucidating numerical analysis (finite element method) using a computer.

Japanese Patent No. 4771338 JP 2009-197091 A Plasticity and processing (Journal of Japan Society for Technology of Plasticity) Vol. 41, No. 476, pages 906 to 910 Plasticity and processing (Journal of Japan Society for Technology of Plasticity) Vol. 42, No. 488, pages 954 to 958 Plasticity and processing (Journal of the Japan Society for Technology of Plasticity) Vol. 41, No. 476, pages 891 to 895 Plasticity and processing (Journal of Japan Society for Technology of Plasticity) Vol. 31, No. 351, pages 502 to 508 Plasticity and processing (Journal of Japan Society for Technology of Plasticity) Vol. 37, No. 428, pp. 933 to 938 Plasticity and processing (Journal of the Japan Society for Technology of Plasticity) Vol. 30, No. 344, pages 1267 to 1274 Plasticity and processing (Journal of Japan Society for Technology of Plasticity) Vol. 30, No. 342, pages 975 to 981 Plasticity and processing (Journal of Japan Society for Technology of Plasticity) Vol. 31, No. 349, pages 202 to 207

  In the above-mentioned experimentally elucidated research, there is no example in which plastic flow in the vicinity of a die hole is visualized in three dimensions dynamically (how it changes from moment to moment), and in addition, when model material is used, plastic flow When quantifying (internal deformation amount), it is necessary to take out the processed product from the mold, so it may be deformed manually when handling the processed product (because the model material is soft), so there is a problem from the viewpoint of accuracy. there were. In addition, the experiment and data analysis required enormous effort and time (several days), and were not practical.

  On the other hand, in the research to clarify by numerical analysis, in the case of three-dimensional plastic flow, it takes enormous analysis time from several days to a week, and it is necessary to interrupt the technical examination. In particular, in the case of three-dimensional deformation, there is no way to physically verify the obtained analysis results.

  The present invention has been made in view of such circumstances, and has a simple configuration and a method for identifying a three-dimensional dead zone shape that is a factor in bending during processing of a metal extruded product such as an aluminum alloy. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, the present invention is configured as follows.

Invention of claim 1, the model material that can reproduce the deformation properties of the metal material, using the model type is made following the density of the model material, spheres only on the outer peripheral portion of the model material in a predetermined shape Embedding
Continuously extruding the model material loaded in the model mold without stopping until the final stroke;
In synchronization with the extrusion, X-rays and X-rays to form a visual difference I. I. Imaging with a camera;
A step of calculating three-dimensional coordinates of the sphere at regular time intervals,
Displaying the movement trajectory of the sphere and the shape data of the model type in an overlapping manner;
A step of identifying a three-dimensional shape of the dead zone based on a result of superimposing and displaying the movement trajectory of the sphere and the shape data of the model type. It is a specific method.

The invention described in claim 2 includes a step of embedding a sphere in the outer periphery of the model material using a model material capable of reproducing the deformation characteristics of the metal material and a transparent model mold,
Continuously extruding the model material loaded in the model mold without stopping;
Synchronously with the extrusion process, the sphere sinks from the outer periphery of the model material to the inside until it becomes unrecognizable, and the movement of the sphere is viewed from two directions forming parallax under visible light. Imaging with a camera;
Calculating the three-dimensional coordinates of the sphere immediately before it sinks into the interior from the outer periphery of the model material and becomes invisible, and specifies the dead zone height in the outer periphery of the model material;
In the cross-section passing through the center of gravity of the sphere and the die centroid when the model material sinks from the outer periphery to the inside, the intersection point between the cross-section and the die upper end surface is the origin, and from the origin to the outer periphery on the die upper end surface Define a coordinate system in which the direction is defined as the positive direction of the X-axis and the direction opposite to the machining direction from the origin as the positive direction of the Y-axis. Using a numerical analysis to approximate a downwardly convex quadratic curve,
A three-dimensional dead zone shape in an extrusion process, comprising: a step of specifying a three-dimensional shape of a dead zone based on a result of superimposing and displaying all the quadratic curves and the shape data of the model type It is a specific method.

According to a third aspect of the invention, the outer peripheral portion of the model material, at least one or more planes perpendicular to the pressing axis, the height of the plane is at equal intervals above the dead zone height 3. The method for specifying a three-dimensional dead zone shape in extrusion processing according to claim 1 or 2, wherein at least one is embedded radially.

  With the above configuration, the present invention has the following effects.

  In this invention, using a clay model material that can reproduce plastic deformation of a metal material with high accuracy, a sphere is used as a material before being embedded in the outer periphery of the model material, and the model material is formed by extrusion. By taking an X-ray image of the movement trajectory of the sphere accompanying the plastic flow in a stereo configuration, the three-dimensional dead zone shape that causes the bending of the extruded product can be easily and reliably identified in a short time. In addition, the dead zone shape of a cross section can be approximated by a quadratic curve just by taking a video camera in a stereo configuration under visible light until the sphere sinks into the inside from the outer periphery of the model material and becomes invisible. By reconstructing the quadratic curves of all cross sections three-dimensionally, the three-dimensional dead zone shape can be specified easily and reliably in a short time.

X-rays in extrusion process I. It is a figure explaining the process of the identification method of the three-dimensional dead zone shape using a camera. It is a figure explaining the process of the identification method of the three-dimensional dead zone shape using the video camera in an extrusion process. It is a figure which shows the structure which embedded the spherical body in the outer peripheral part of model material. It is a figure which shows a three-dimensional plastic flow visualization system. It is a figure explaining the similarity of a model material (special clay) which can reproduce deformation of metal material, and deformation. It is a photograph explaining the structure of a three-dimensional visualization system. It is a circuit diagram explaining a three-dimensional visualization system. It is an external view of an experimental model type. It is sectional drawing of an experimental model type | mold. It is a figure which shows the dice | dies used in experiment. It is a figure which shows a model experiment and visualization result. It is explanatory drawing for estimating a coordinate system and a dead zone height. It is a figure which shows the comparison with the dead zone represented by the estimated quadratic curve, and Example 1. FIG. It is a figure which shows the structure of an extrusion tool. It is a figure which shows a dead zone and a product defect.

  Hereinafter, an embodiment of a method for specifying a three-dimensional dead zone shape in extrusion processing of a metal material according to the present invention will be described. Although this embodiment shows the preferable form of this invention, this invention is not limited to this.

[Specification method 1 of three-dimensional dead zone shape in extrusion processing]
As shown in FIG. 1, the method for specifying the three-dimensional dead zone shape in the extrusion process of this embodiment includes a step A1 for embedding a sphere 3, a step B1 for extrusion, a step C1 for imaging, a step D1 for calculation, and a display. Step E1 is performed by the procedure of Step F1 for specifying the three-dimensional dead zone shape. In addition, process B1 and process C1 are extruded (namely, implemented synchronously), imaging.

  The step A1 for embedding the sphere 3 uses the model mold 1 and the model material 2 that can reproduce the deformation characteristics of the metal material, and the sphere is formed on the outer surface of the model material 2 having a predetermined shape (a cylinder in the figure). 3 is an embedding process. In the step A1 for embedding the sphere 3, the sphere 3 is arranged on at least one plane perpendicular to the pressure axis (in the case of 2 in the figure, 2) on the outer periphery of the cylindrical model material 2 as shown in FIG. Two or more planes) are embedded radially at equal intervals. Note that the position in the height direction with respect to the flat material perpendicular to the pressing axis needs to be set higher than the dead zone height in the outer peripheral portion. When the dead zone height at the outer peripheral portion is unknown, as a preliminary model experiment, only one sphere 3 is formed at the center and upper end (on the opposite side of the die 110) in the height direction of the cylindrical model material 2. What is necessary is just to implement an embedding extrusion process in between. That is, since the sphere 3 sinks from the outer peripheral portion of the model material 2 to the inside, the position becomes the dead zone height in the outer peripheral portion. In the case of FIG. 3, the sphere 3 is embedded in two planes that are perpendicular to the pressure axis and have different heights in the direction of the pressure axis. In this way, it is possible to avoid overlapping of the spheres 3 when X-ray imaging is performed from the side, and to specify the position coordinates of all the spheres 3 that are radially embedded. The sphere 3 is easily embedded in the model material 2 by pushing the hard metal sphere 3 into the predetermined position where the hard metal sphere 3 is pre-marked with respect to the soft clay-like model material 2 by the diameter of the sphere 3 with a finger. it can.

  Extrusion process B1 is a process in which the model material 2 loaded in the model mold 1 is continuously extruded without stopping until the final stroke. By this extrusion processing, the minimum necessary number of spheres 3 embedded only in the outer peripheral portion of the model material 2 move with the three-dimensional plastic flow of the model material 2.

  The process C1 for imaging is from the unsteady deformation state of extrusion processing (from the start of processing to the front of the steady deformation body, the process in which the deformation region inside the material changes every moment) to the steady deformation state (time passes) The process of not changing the deformation region inside the material), the sphere 3 until the sphere 3 flows out of the die hole 110a, the X-ray from two directions forming the parallax and one X-ray I.D. I. This is a step of imaging with a camera.

  The calculating step D1 is a step of calculating the three-dimensional coordinates of the sphere 3 and the velocity vector at regular time intervals.

  The displaying step E1 is a step of displaying the shape data or velocity vector of the sphere 3 in three-dimensional coordinates and the shape data of the model type 1 in a superimposed manner.

  The process F1 for specifying the three-dimensional dead zone shape is performed by displaying a plurality of two-dimensional cross sections including the pressure axis based on the result of overlaying and displaying the shape data of the sphere 3 and the shape data of the model die 1. This is a step of specifying the three-dimensional shape of the dead zone so that the mold designer can easily recognize it. The operation time required from the above steps A1 to F1 is within one hour, which is more practical than other methods.

[Method for specifying 3D dead zone shape in extrusion process 2]
As shown in FIG. 2, the method of specifying the three-dimensional dead zone shape in the extrusion process of this embodiment includes a process A2 for embedding a sphere 3, a process B2 for extruding, a process C2 for imaging, and 3 at the time when the sphere sinks. The process is performed by the process D2 for calculating the dimensional coordinates and calculating the dead zone height, the process E2 for approximating the dead zone shape of one cross section with a quadratic curve, and the process F2 for specifying the 3D dead zone shape. In addition, process B2 and process C2 are extruded (namely, implemented synchronously), imaging.

  The step A2 for embedding the sphere 3 is a step for embedding the sphere 3 on the outer surface of the cylindrical model material 2 using the transparent model mold 1 and using the model material 2 that can reproduce the deformation characteristics of the metal material. . In the step A2 of embedding the sphere 3, at least one or more of them are radially embedded in the outer peripheral portion of the cylindrical model material 2 shown in FIG. In addition, it is necessary to set the height from the upper end surface of the die 110 in a plane perpendicular to the pressure axis to be higher than the dead zone height in the outer peripheral portion. If the dead zone height at the outer periphery is unknown, it is set according to the procedure described in paragraph [0022]. In this implementation, since the transparent model mold 1 is used, the sphere 3 on the outer surface can be tracked under visible light, and it is not necessary to avoid overlapping as in the specifying method 1.

  The process B2 of extruding is a process of continuously extruding the model material 2 loaded in the model mold 1 without stopping halfway. By this extrusion process, the minimum necessary number of spheres 3 embedded only in the outer periphery of the model material 2 move with the three-dimensional plastic flow of the model material 2.

  In the imaging step C2, the sphere 3 from the start of the extrusion process to the point when it sinks (becomes invisible) from the outer periphery of the model material 2 is imaged under visible light by the video camera 19 from two directions forming parallax. It is a process to do. Of the spheres 3 embedded radially, the spheres 3 that are on the back side of the model material 2 and cannot be seen may be rotated by rotating the turntable 11 to the visible position and repeating the extrusion model experiment a plurality of times.

  In the step D2 of calculating the dead zone height, the three-dimensional coordinates of the sphere 3 at the time when the plastic flow progresses and the model material 2 sinks into the inside (disappears) from the outer periphery, and the distance from the upper end surface of the die 110 is calculated. Is a step of calculating. This process is repeated for all spheres 3.

  The step E2 of approximating the dead zone shape of one cross section with a quadratic curve is a cross section passing through the center of gravity of the sphere 3 and the dice centroid at the time of sinking from the outer periphery of the model material 2 to the one sphere 3 of interest. , The intersection between the cross section and the upper end surface of the die 110 is the origin, the direction from the origin toward the outer periphery on the upper end surface of the die 110 is the positive direction of the X axis, and the direction opposite to the machining direction from the origin is the positive direction of the Y axis. In this step, a coordinate system is defined and approximated by a quadratic curve that protrudes downward numerically using the origin where the coordinates are known and the dead zone height at the outer periphery of the model material 2. This process is repeated for all spheres 3.

  The step F2 for specifying the three-dimensional dead zone shape is performed so that the mold designer can easily recognize the result based on the result of superimposing and displaying all the obtained quadratic curves and the shape data of the model die 1. This is a step of specifying the three-dimensional shape of the zone. The operation time required from A2 to F2 is within one hour, which is more practical than other methods.

  As in the identification methods 1 and 2, using the model material 2 that can reproduce the plastic deformation of the metal material with high accuracy, the necessary minimum number of spheres 3 are embedded in the outer periphery of the model material 2, and the model material 2 X-ray imaging of the movement trajectory of the sphere 3 due to plastic flow or video shooting under visible light until the sphere 3 embedded in the outer periphery sinks into the model material, during the extrusion of the extruded product of the metal material The three-dimensional dead zone shape that causes the bending can be easily and reliably specified in a short time.

  In any method of specifying the three-dimensional dead zone shape in the extrusion process of this embodiment, the three-dimensional plastic flow visualization system shown in FIG. 4 and a model material (special material that can reproduce the deformation of the metal material shown in FIG. 5A) Model experiment using a clay). FIGS. 5A and 5B show the results of demonstrating the similarity of deformation between the model material and the aluminum alloy. The deformation patterns are similar, indicating that the plastic deformation characteristics of metal materials can be reproduced with model materials.

  The three-dimensional plastic flow visualization system shown in FIG. 4 includes a rotating table 11, a pressing device 12, an X-ray generator 13, an X-ray I.D. I. A camera 14 or a video camera 19 is disposed, the resin extrusion model die 1 is placed on the turntable 11, and the cylindrical model material 2 in the model die 1 is pressed by the pressing device 12 to the X-ray on the model die 1. X-rays are emitted by the generator 13 and X-rays I.V. I. The camera 14 is used for photographing, or the transparent model mold 1 is photographed using the video camera 19.

  In the model experiment, at least one or more metal (hard metal) microspheres (diameter 0.5 to 1.5 mm) are embedded in the outer surface of the model material 2 as the sphere 3 for detecting plastic flow, and a resin extrusion model die When the pressure is applied within 1, the plastic flow is represented as a movement locus of the sphere 3. Here, in the case of the specifying method 1, the movement trajectory (three-dimensional coordinates) indicates that the X-ray generator 13 (two units) that controls the irradiation time and one X-ray I.D. I. In the case of the specific method 2 by stereoscopic shooting using the camera 14, three-dimensional high-precision measurement can be performed by stereoscopic shooting using the two video cameras 19.

[Example]
Next, examples (two cases) of the method for specifying the three-dimensional dead zone shape in the extrusion process will be described.
[Example 1-X-ray I. I. Dead zone identification method using a camera]
(Visualization system)
A photograph and a schematic diagram of the visualization system are shown in FIGS. The visualization system includes a stereo X-ray generator 13 (maximum tube voltage 100 kV, maximum tube current 0.1 mA, distance between X-ray generators (parallax interval) 120 mm) and X-ray I.D. I. A camera 14 (field of view: 112 mm × 86 mm) was installed relative to each other. In addition, pressing device 12 (maximum pressurization capacity 9.8 kN), 360 ° rotation and 3-axis operation (up / down 0-200 mm, X-ray irradiation direction 0-150 mm, X-ray irradiation axis perpendicular direction 0-300 mm) It was comprised with the base 11, the control apparatus 16, the image capture board 15, the display part 17, PC30, and data processing software (not shown). The processing force and punch displacement were measured by a measuring instrument 18 incorporated in the system.

  In the system operation of the visualization system, first, the control device 16 was controlled from the PC 30 to adjust the position and angle of the turntable 11, and then the pressurizing amount of extrusion was input from the PC 30 to the control device 16. Next, the X-ray generator 13 and the X-ray I.D. I. Using the model mold 1 placed between the cameras 14, pressurization was started by the pressing device 12. Here, simultaneously with the pressure deformation, the X-rays were irradiated while the two X-ray generators 13 were switched on and off for each frame (1/30 second) of the NTSC (video) signal with an electronic shutter. Finally, X-ray I.D. I. An NTSC (video) signal photographed by the camera 14 was captured into the PC 30 via the image capture board 15 (stored in the storage device 31) and displayed on the display unit 17.

  Thereafter, the data stored in the storage device 31 was sorted according to the X-ray irradiation direction, and re-saved in the storage device 31 as a stereo image (JPEG format, 8-bit monochrome, 640 × 480 pixels). The two-dimensional (center of gravity) position coordinates of the sphere 3 were identified for each successive frame from the obtained stereo image by image processing. If the three-dimensional position coordinates are calculated by the principle of triangulation based on the two-dimensional position coordinates of the sphere 3 according to the above time series and X-ray irradiation direction, the real-time three-dimensional measurement of the sphere movement coordinates becomes possible. Here, since the time interval between frames of the NTSC (video) signal is known, the velocity vector of the sphere 3 can be calculated. Once the speed vector is known, the degree of speed difference that is the cause of bending can be grasped.

(Model type used for visualization experiment)
FIG. 8 is an external view of the model mold 1 used in the visualization experiment, and FIG. 9 is a cross-sectional view of the model mold 1. The model mold 1 is attached to a model mold installation table 11a and a model mold installation lid 11b installed on the turntable 11, and is pressed by a press cylinder 12a of a pressing device 12 (detail drawing is omitted). The model mold 1 has a structure in which a die base 22 and a die 23 are arranged in a container 21, a flow guide 24 is installed between the cylindrical model material 2 and the die 23, and the model material 2 is pressed through a pressing plate 25. It is.

  The model mold 1 is made of a resin that easily transmits X-rays in order to improve the visibility of the sphere 3 for tracking the amount of plastic deformation. By doing this, since the high-density sphere 3 (imaged as a black dot) is imaged with good contrast in the low-density resin mold (imaged as a light gray background), only the sphere 3 is captured. It becomes possible to track. Although the press cylinder 12a and the turntable 11 of the pressing device 12 are made of metal, the X-ray I.D. I. Since it is out of the field of view of the camera 14, it does not disturb the shooting of the sphere 3. The model material 2 extruded in the experiment has a structure that slides on the lower slide base 50, is gently bent, and is discharged out of the mold. The model material 2 was a cylinder having a diameter of 50 mm and a height of 50 mm. The container 21 was made as thin as possible (thickness 3 mm) in order to facilitate the transmission of X-rays.

(Die hole shape)
The shape of the die hole 23a of the die 23 used in the model experiment is shown in FIG. The shape of the die hole 23a is a C-shaped (C-Channel) that is often used in the actual extrusion process, and the die 23 is a disk-shaped plate having a thickness of 2 mm.

(Experimental conditions)
The material shown in Patent Document 2 was used as the model material 2, and the components were adjusted so that the plastic deformation state of the hot working of the aluminum alloy could be reproduced. In the production of the material using the model material 2, the model material 2 was kneaded and deaerated with a vacuum kneader, and then extruded into a cylindrical shape having a diameter of 50 mm and a height of 50 mm. Next, in order to stabilize mechanical properties, it was kept in a thermostatic chamber at 20 ° C. for 24 hours or more. Embedding the sphere 3 in the model material 2 should minimize the number of embeddings in consideration of various circumstances such as improvement of experimental efficiency, cost reduction, speed of data processing and improvement of accuracy. Therefore, the following hypothesis was assumed prior to the experiment.

<Hypothesis>
It was assumed that in the extrusion process, a dead zone was formed at the initial stage of pressurization, and the plastic flowed so that the material slipped on the three-dimensional dead zone that became a mass that did not flow plastically.

  If this hypothesis is true, it is not necessary to embed the sphere 3 in the model material 2, and the number of spheres can be minimized by embedding only in the outer periphery. That is, it was considered that the three-dimensional shape of the dead zone can be specified by photographing the movement locus of the sphere 3 that plastically flows from the outer diameter portion to the die hole 23a.

  Therefore, in the experiment, as shown in FIG. 3, 16 spheres 3 were embedded at intervals of 22.5 °. 3A is a front view of the model material 2, FIG. 3B is a top view of the model material 2, and FIG. 3C is a perspective view of the model material 2. In order to visually recognize all the spheres 3 individually and to trace the trajectory in time series, the spheres 3 were embedded in a two-stage structure of 8 pieces at a position 14 mm from the bottom surface and 8 pieces at a position 12 mm. In the model experiment, soapy water was used as the lubricant, and the pressure was continuously applied without stopping halfway until the amount of pressure reached 35 mm at a pressure rate of 0.3 mm / s. X-rays were set at a tube voltage of 100 kV and a tube current of 0.1 mA, X-ray irradiation and imaging were started 1 second before pressurization, and ended simultaneously with the end of pressurization. In addition, it compared with the case where the sphere 3 is not embedded by this experiment, and it confirmed that the sphere 3 did not inhibit the plastic flow of the model material 2. FIG. In this experiment, the flow guide 24 is not installed in order to see how much bending occurs when the flow guide 24 is not provided.

[Dead zone identification result]
The model experiment and visualization results are shown in FIG. FIG. 11A is a three-dimensional display of a dead zone shape. The dead zone shape indicated by the space between the sphere 3 and the dice 23 could be specified only by displaying the 16 spheres 3 in time series (10-second intervals). That is, it can be said that the <hypothesis> in paragraph [0046] has been proved. FIG. 11B shows a cross-sectional number corresponding to FIG. 11C viewed from above, and FIG. 11C shows a two-dimensional display of the dead zone shape in each cross section.

  Since the C shape (C-Channel) is line symmetric, the dead zone shape is symmetric except for the cross section (1), and it was found that the asymmetry of the cross section (1) is a factor causing bending of the workpiece. In addition, the dead zone height of the cross section (1) was 7 mm and 8 mm, respectively. Further, when the flow guide 24 was not used, the initial bending angle of the extrusion process was 15.86 °. Note that the bending of the processed product is defined as an angle formed by the pressure axis and the material outflow direction as shown in FIG. 15, and is called a bending angle.

[Example 2-Dead zone identification method using video camera]
(Visualization system)
The visualization system includes an X-ray generator 13 and an X-ray I.D. I. Except that the camera 14 is replaced with a video camera 19, the operation is the same as in the first embodiment. The parallax interval between the two video cameras 19 was 120 mm.

  The system operation of the visualization system is the same as in paragraph [0040]. Simultaneously with the pressure deformation, video was taken until the sphere 3 embedded in the outer periphery of the model material 2 was submerged inside the model material with two video cameras 19. Finally, the captured NTSC (video) signal was captured into the PC 30 via the image capture board 15 (stored in the storage device 31) and displayed on the display unit 17.

  Thereafter, the two-dimensional (center of gravity) position coordinates of the sphere 3 were identified for each frame at a fixed time interval by image processing from the stereo image (JPEG format, 8-bit monochrome, 640 × 480 pixels) stored in the storage device 31. Three-dimensional position coordinates were calculated based on the principle of triangulation based on the two-dimensional position coordinates of the sphere 3 for each time series and parallax image.

(Model type used for visualization experiment)
The model type used for the visualization experiment is the same as in Example 1.

  In the model mold 1, the container 21 is made of a transparent resin so that the sphere 3 for tracking the amount of plastic deformation can be seen even under visible light. The model material 2 extruded in the experiment has a structure that slides on the lower slide base 50, is gently bent, and is discharged out of the mold. The model material 2 was a cylinder having a diameter of 50 mm and a height of 50 mm. The container 21 was made as thin as possible (thickness 3 mm) in order to ensure transparency.

(Die hole shape)
The die hole 23a of the die 23 used in the model experiment is the same as that in the first embodiment.

(Experimental conditions)
The material of the model material 2 is the same as that of the first embodiment. The production of the material using the model material 2 is the same as that in the first embodiment. Embedding the sphere 3 in the model material 2 should minimize the number of embeddings in consideration of various circumstances such as improvement of experimental efficiency, cost reduction, speed of data processing and improvement of accuracy. Therefore, the following hypothesis was assumed prior to the experiment.

<Hypothesis>
“When the extrusion process proceeds, the sphere 3 embedded in the outer periphery of the model material 2 moves linearly in the pressurizing direction in the outer periphery, and then reaches the dead zone formed in the initial stage of pressurization. It sinks inside (becomes invisible with a video camera under visible light), and then follows a trajectory approximating the dead zone with a quadratic curve, reaches the die hole 110a, and flows out. " Note that the approximation with the quadratic curve is appropriate even if it is judged from the dead zone shape of FIG. 11C of Example 1 which is an actual physical phenomenon.

[About model experiments]
The shape of the model material 2 and the number of spheres 3 used in the experiment are the same as in the first embodiment. Among these spheres 3, only one sphere 3 corresponding to the right side (dead zone height 8 mm side) of the cross section (1) shown in FIG. Processed. The model experiment conditions are the same as in the first embodiment except for the shooting method.

[Method for estimating dead zone shape in cross section]
The model experiment / visualization results are shown in FIG. FIG. 12A shows a top view of the die 110, and FIG. 12B shows a cross section passing through the center of gravity of the sphere and the die centroid at the time of sinking from the outer periphery to the inside. When the three-dimensional coordinates of the sphere at the time of subduction were calculated to determine the dead zone height H at the outer periphery, it was 8 mm. Next, the coordinates where the crossing point and the die top surface are the origin, the direction from the origin to the outer periphery on the die top surface is the positive direction of the X axis, and the direction opposite to the machining direction from the origin is the positive direction of the Y axis A system was defined. Here, the distance (known) from the origin to the outer periphery of the model material 2 is R, and the dead zone shape of the cross section (1) is a quadratic curve Y = aX ² + bX + C (1)
Approximate.
Here, since (X, Y) = (0, 0) and (X, Y) = (R, H) are known, when X = 0 and Y = 0, the equation (1) is expressed as C = Since it is 0, Formula (1) becomes Y = aX < ² > + bX ... Formula (2)
It becomes. When X = R, Y = H, so H = aR ² + bR (3)
Here, since the quadratic curve is convex downward, when a and b are obtained numerically under the condition of a> 0, the quadratic curve, that is, the dead zone shape in a certain cross section can be estimated. In the case of the formula (3), a = H / 2R ² and b = H / 2R, which is a quadratic curve obtained by the following formula (4).
Y = (H / 2R ² ) X ² + (H / 2R) X (4)
As shown in FIG. 13, the obtained quadratic curve almost coincides with the actually measured dead zone shape of Example 1. That is, it can be said that the <hypothesis> in paragraph [0058] has been proved.

[Three-dimensional dead zone shape estimation method]
The dead zone shape approximated by the quadratic curve in the above cross section is applied to all the spheres 3 and the dead zone is determined based on the result of overlaying and displaying the estimated quadratic curve and the shape data of the model type 1. A three-dimensional shape can be estimated.

  In this way, using a model material that can accurately reproduce the plastic deformation of a metal material, the minimum number of metal spheres embedded in the outer periphery of the material, and the movement trajectory of the sphere accompanying the plastic flow of the model material is photographed. By doing this, it is possible to easily and reliably specify the three-dimensional dead zone shape that causes the bending of the extruded product.

  The present invention is applied to a method for identifying a three-dimensional dead zone shape that causes the bending of the extruded product, and quantifies the three-dimensional dead zone shape that causes the bending of the extruded product with a simple configuration. can do.

A1 Embedding sphere B1 Extrusion process C1 Imaging process D1 Computation process E1 Displaying process F1 Identifying the 3D dead zone shape A2 Embedding sphere B2 Extrusion process C2 Imaging process D2 Dead zone height Step E2 for calculating the height Step F2 for approximating the dead zone shape of one cross section with a quadratic curve Step 2 for specifying the three-dimensional dead zone shape 1 Model type 2 Model material 3 Sphere 10 X-ray defense wall 11 Turntable 12 Pressing device 13 X-ray generator 14 X-ray I. Camera 15 Image capture board 16 Controller 17 Display unit 18 Measuring instrument 19 Video camera 21 Container 22 Die base 23 Dice 24 Flow guide 25 Press plate 30 PC
31 Storage device

Claims (3)

A step of embedding a sphere only in the outer periphery of the model material having a predetermined shape, using a model material capable of reproducing the deformation characteristics of the metal material, and a model mold whose material is less than the density of the model material;
Continuously extruding the model material loaded in the model mold without stopping until the final stroke;
In synchronization with the extrusion, X-rays and X-rays to form a visual difference I. I. Imaging with a camera;
A step of calculating three-dimensional coordinates of the sphere at regular time intervals,
Displaying the movement trajectory of the sphere and the shape data of the model type in an overlapping manner;
A step of identifying a three-dimensional shape of the dead zone based on a result of superimposing and displaying the movement trajectory of the sphere and the shape data of the model type. Identification method. Using a model material capable of reproducing the deformation characteristics of a metal material and a transparent model mold, and embedding a sphere in the outer periphery of the model material;
Continuously extruding the model material loaded in the model mold without stopping;
Synchronously with the extrusion process, the sphere sinks from the outer periphery of the model material to the inside until it becomes unrecognizable, and the movement of the sphere is viewed from two directions forming parallax under visible light. Imaging with a camera;
Calculating the three-dimensional coordinates of the sphere immediately before it sinks into the interior from the outer periphery of the model material and becomes invisible, and specifies the dead zone height in the outer periphery of the model material;
In the cross-section passing through the center of gravity of the sphere and the die centroid when the model material sinks from the outer periphery to the inside, the intersection point between the cross-section and the die upper end surface is the origin, and from the origin to the outer periphery on the die upper end surface Define a coordinate system in which the direction is defined as the positive direction of the X axis and the direction opposite to the machining direction from the origin as the positive direction of the Y axis, and the coordinates at the time of sinking inward from the outer periphery of the origin and the model material are defined Using a numerical analysis to approximate a downwardly convex quadratic curve,
A three-dimensional dead zone shape in an extrusion process, comprising: a step of specifying a three-dimensional shape of a dead zone based on a result of superimposing and displaying all the quadratic curves and the shape data of the model type How to identify. At least one or more planes perpendicular to the pressure axis are embedded in the outer periphery of the model material, and at least one or more planes are embedded radially at equal intervals above the dead zone height. The method for specifying a three-dimensional dead zone shape in extrusion processing according to claim 1 or 2,