JP2013123719A - Method and device for predicting lifetime of forging die, and program for predicting the lifetime of forging die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prediction technology of abrasion amount with high precision, which is specified to the flash surface of a forging die, in the technology of performing forging using the forging die while generating burrs.SOLUTION: In the technology of performing forging using forging dies 11, 12 while generating burrs 14, the number of shots leading to lifetime of the forging dies 11, 12 is calculated using the fact that the product of the movement of the burrs 14 in one shot obtained by the simulation and the number of shots is in direct proportion to the measured abrasion amount of flash surfaces 11a, 12a.

Description

  The present invention relates to a technique for predicting the life of a forging die.

  CAE analysis is known as a method for predicting wear of a forging die (see, for example, Patent Document 1).

JP 2007-283385 A

  For example, there is a method of forging the work material while pressurizing the work material with a mold and generating burrs. According to the analysis by the present inventors, in this technique, a portion where the burr around the portion constituting the cavity of the mold is pushed (this portion is called a flash surface) is subjected to great friction, and the wear in this portion is reduced. It has been found that it mainly affects the life of the mold.

  By the way, in the wear prediction technology for forging dies in the prior art, the wear of the forging dies is predicted using mathematical formulas derived experimentally using various parameters. It is not at a level where the wear state can be accurately predicted. In particular, the wear prediction simulation of a forging die according to the prior art is low in accuracy in predicting the wear of the die in the technique of forging while forming the above-described burrs, and is empirically based on wear according to the actual machine. At present, the life of the forging die is estimated.

  In such a background, the present invention provides a highly accurate wear amount prediction technique specialized in the flash surface of a forging die in the forging technique using a forging die while generating burrs. With the goal.

  The invention according to claim 1 is a method for predicting the life of a forging die, the product of the amount of burrs moving and the number of shots during forging, and the amount of wear of the portion of the forging die that contacts the burrs. The number of shots that can withstand the use of the forging die is calculated based on the relationship between the forging die and the forging die life prediction method.

  First, the principle of the present invention will be described. FIG. 1 is a principle diagram for explaining the principle of forging while generating burrs. FIG. 1 shows an exaggerated view of the workpiece 13 that is pressed by the forging dies 11 and 12 and subjected to forging treatment. FIG. 1 conceptually shows forging dies 11 and 12 separated vertically and a work material (metal material processed by forging) 13 sandwiched between the forging dies 11 and 12 and receiving pressure. Is shown in In FIG. 1, the part of the code | symbol 14 is a burr | flash, and the part of the metal mold | die which presses and restrains this burr | flash 14 is flash surface 11a, 12a. A space is secured between the flash surfaces 11a and 12a by a structure (not shown), and a gap through which the burr 14 is pushed out is secured. As shown in the drawing, the work material is plastically deformed by applying pressure so as to press the forging dies 11 and 12 relative to each other, and the work material 13 follows the shape of the forging dies 11 and 12. Is deformed.

  In this forging technique, the burrs of the work material are pushed out and moved in the gap portion between the flash surfaces 11a and 12a, so that the work material 13 is deformed with tension. At this time, the burr 14 moves extending in the left and right directions in the figure while rubbing the flash surfaces 11a and 12a.

  In the present invention, attention is paid to the moving distance of the burr 14 that moves so as to extend outward while in contact with the flash surfaces 11a and 11b. According to the knowledge of the present inventors, the product of the movement distance of the burr 14 and the number of shots in one shot (one forging process) obtained by simulation under the condition that the same process is repeated a plurality of times is This is directly proportional to the actual wear amount of the flash surfaces 11a and 12a when the processing is performed. The present invention uses this phenomenon to predict the number of shots that are possible until a predetermined amount of wear is reached.

  That is, in the technique of performing forging while generating burrs using a forging die, forging failure occurs mainly due to progress of wear on the flash surface. Therefore, the wear of the flash surface is the main factor that determines the life of the mold. On the other hand, as described above, according to the knowledge found by the present inventors, the product of the amount of movement of burrs and the number of shots during forging has a specific relationship with the actual amount of wear on the flash surface. Therefore, in the present invention, by giving a limit wear amount, the number of shots reaching the limit wear amount (that is, the number of shots until the end of the life) is calculated from the above specific relationship.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the amount of movement of the burr is obtained by simulation, and the amount of wear is obtained by actual measurement.

  The invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2, the portion of the forging die that is most worn is selected as the portion that contacts the burr. According to the analysis by the present inventors, the wear amount of the portion where the wear due to the generation of burrs is the most intensely correlates most strongly with the life of the forging die. Therefore, the number of shots until the forging die reaches the end of its life can be predicted with higher accuracy by selecting the portion with the greatest wear in the forging die as the portion for evaluating the wear amount.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, a plurality of parts are selected as a part from which the amount of movement of the burr is acquired and a part that contacts the burr. Features. When only one pinpoint is selected as the part that focuses on the amount of movement of the burr and the part that contacts the burr, the possibility that the error will increase increases. On the other hand, errors can be suppressed by making a plurality of sampling points and taking the average.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the product of a movement amount and a shot number of burrs during the forging and the burr of the forging die contacts It is characterized in that the relationship with the amount of wear of the portion to be in direct proportion. Since the relationship is directly proportional, the calculation related to the processing can be simplified and high prediction accuracy can be obtained.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the forging die is constituted by a pair of dies, and the work material is between the pair of dies. Forging is performed, and the burrs are generated by being sandwiched between flash surfaces provided in the pair of molds during the forging.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein as the forging die, the processing accuracy for the same work material is different, and the life expectancy is A plurality of types having different wear amounts are prepared, and the relationship between the product of the amount of burrs moved and the number of shots during the forging and the amount of wear of the portion in contact with the burrs of the forging die is The plurality of types of forging dies are substantially the same. According to the seventh aspect of the present invention, the same relationship is applied to both of a relatively low-precision forging die (for example, a rough die) and a relatively high-precision forging die (for example, a finishing die). Formulas can be applied, the related processing is simplified, and the amount of data required can be reduced. Moreover, if the object to be processed is the same, there is no need to re-acquire data when using dies having different accuracy, and the processing can be made more efficient.

  The invention according to claim 8 is an apparatus for predicting the life of a forging die, the product of the amount of burrs moving and the number of shots during forging, and the amount of wear of the portion of the forging die that contacts the burrs. The forging die life prediction apparatus is provided with a calculation unit that calculates the number of shots that can withstand the use of the forging die based on the relationship between the forging die.

  The invention according to claim 9 is a program for causing a computer to read the life of a forging die and for predicting the life of the forging die. On the basis of the relationship with the amount of wear of the portion of the metal mold that contacts the burr, the program functions as a calculation means for calculating the number of shots that can withstand the use of the metal mold for forging.

  ADVANTAGE OF THE INVENTION According to this invention, in the forging technique using a forging die while generating burrs, a highly accurate wear amount prediction technique specialized for the flash surface of the forging die is provided.

It is a principle figure explaining the principle which forges while producing a burr | flash. It is a schematic diagram which shows the outline | summary of the preformed product of a crankshaft. It is a top view of the metal mold | die for forging. It is a graph which shows the relationship between the product of the movement amount of a burr | flash, and the number of shots, and the measured amount of wear. It is a block diagram which shows an example of the lifetime prediction processing apparatus of the metal mold | die for forging. It is a block diagram which shows an example of the procedure of the process which estimates the lifetime of the metal mold | die for forging.

1. First Embodiment Hereinafter, an embodiment of the present invention will be described. FIG. 2 shows a crankshaft preform 100 manufactured using the present invention. The crankshaft preform 100 includes a journal shaft portion 101, and the journal shaft portion 101 is provided with an arm portion 102. Adjacent arm portions 102 are connected by a crankpin portion 103. The crankpin portion 103 is disposed in parallel with the journal shaft portion 101. In this example, the material (work material) constituting the crankshaft preform 100 is carbon steel generally used as a crankshaft.

  FIG. 3 shows a top view of a forging die 300 for forging the crankshaft preform 100 shown in FIG. 2 by forging. Another forging die 300 is prepared, and an upper forging die and a lower forging die corresponding to the forging dies 11 and 12 of FIG. 1 are prepared. FIG. 3 shows one of them (an upper forging die or a lower forging die).

  FIG. 3 shows the cavity portion 301 of the forging die 300. The cavity 301 has a concave shape corresponding to the preform 100 of the crankshaft. A flash surface 302 is provided around the cavity 301. The outside of the flash surface 302 is a dug-down surface 303 dug down. On the dug down surface 303, an interval holding unit 304 is provided. The same thing as the space | interval holding | maintenance part 304 is provided also in the flash surface of another forging metal mold | die (not shown) which opposes. A predetermined gap for forming a burr between the opposing flash surfaces is ensured by the contact between the two opposing space holding portions.

  A forging die 300 shown in FIG. 3 is a finishing die. In this example, there are three types of forging dies: a crushing die, a rough die, and a finishing die. The crushing mold is a mold for performing the first stage of forging, and is a mold for forming the general appearance of the crankshaft preform 100 first. The rough die is a die for performing the second stage forging, and is a die for forging the one formed by the crushing die with an accuracy of one rank higher. The finishing die is a die for performing the third-stage forging, and is a die for further finishing forging the preform formed by the rough die.

  The difference between the crushing type, the rough type, and the finishing type is in the accuracy of making the cavity. In addition, since the optimum state of burrs is different at each stage, the area of the flash surface and the distance between the flash surfaces of two opposing molds are different. Of course, forging conditions such as pressure are also different. In addition, although the case where the crankshaft preform 100 is forged using three types of dies is illustrated here, the types are not limited to three types.

  According to the demonstration test, it has been found that the wear of the flash surface 302 tends to be particularly large in the portion indicated by reference numeral 305 in FIG. This is presumably because the load applied to the flash surface 302 in the portion 305 at the time of occurrence of burrs is relatively larger than that in other portions.

  In FIG. 4, the product of the amount of movement of burrs (∫Vdt) and the number of shots (number of forgings) in the process of generating burrs on the flash surface 302 is taken on the horizontal axis, and the measurement was performed under the conditions where the values on the horizontal axis were obtained. It is the graph which took the amount of wear in flash surface 302 on the vertical axis. Note that the values on the vertical axis and the horizontal axis are normalized relative values. Here, the movement amount of the burr is a value obtained by calculation by computer simulation, and the value of the wear amount on the flash surface 302 is a value actually measured by a three-dimensional digitizer. Also, when using the pinpoint value, there is a high possibility of deviation, so the target area is divided into a plurality of 3 mm mesh small areas, and the values at the center points of the divided small areas are Average value is adopted. Note that the movement amount of the burr, which is the value on the horizontal axis in FIG. 4, is the movement distance by which the fluidized work material moves relative to a specific point portion of the flash surface 302 in the process of burr generation. It is. Here, the movement amount of the burr is calculated as a value (∫Vdt) obtained by integrating the movement speed V of the burr with the movement time.

  FIG. 4 shows plot points in the finish mold indicated by ● and plot points in the rough mold indicated by ■. The finishing mold and the rough mold are made of the same material, and a plurality of shots performed in each mold are performed under the same conditions.

  Since the forging conditions are different, the amount of burr movement (∫Vdt) in one shot (one forging) is different between the finishing die and the rough die. However, as is clear from FIG. 4, the value obtained by multiplying the amount of movement of burrs (∫Vdt) and the number of shots in one shot and the measured amount of wear when forging is performed under these conditions are the finish mold Ride on the same straight line with rough type. That is, regardless of the forging conditions, the value of (the amount of movement of burrs (∫Vdt) × number of shots) (horizontal axis in FIG. 4) and the amount of wear on the flash surface of the actual forging die under these conditions Are in the same relationship.

  As described above, the forging failure in the technique of forging using a forging die while generating burrs mainly depends on the wear of the flash surface of the forging die. Therefore, in this technique, the life of the forging die can be accurately predicted by evaluating the wear of the flash surface. Further, since the crushing die, the rough die, and the finishing die each have different required forging accuracy, the relationship between the wear of the flash surface and the life is also different. For example, in the rough type, the wear amount of the flash surface is allowed up to 2.5 mm, but in the finished type, the value is 0.8 mm to 0.9 mm.

  If this and the graph shown in FIG. 4 are used, it is possible to predict the life of the forging die. For example, in the forging process for the crankshaft preform 100 using the forging die (finishing die) 300 of FIG. 3, the burr movement amount X (= ∫Vdt) on the flash surface 302 per shot is It is calculated by computer simulation, and it is assumed that the life of the forging die is W in terms of the amount of wear on the flash surface 302. Here, from FIG. 4, the proportionality constant is A, the number of shots is S, and there is a relationship of W = A (∫Vdt) S, and the proportionality constant A is obtained from FIG. The number of shots S up to can be calculated. Thus, it is possible to predict how many shots the forging die will have a life.

  Since the graph of FIG. 4 has high linearity, the accuracy of predicting the life of a forging die using the relationship of FIG. 4 is extremely high. Further, since the computer simulation for calculating the movement distance of the flash on the flash surface is also a simulation for predicting the behavior of the material to be processed in a specific portion, it can be performed with high accuracy and the calculation can be easily performed. In addition, the life can be predicted using the same formula regardless of the use (accuracy) of forging dies such as crushing dies, rough dies, and finishing dies. There is no need to prepare data. Further, the contents of the processing are simple and practical. In addition, although the example in the case of shape | molding the crankshaft preform by forging was demonstrated here, the object of shaping | molding is not limited to a crankshaft. Further, the material is not limited to the exemplified materials as long as it is a metal material that can be forged using a forging die.

2. Second embodiment (configuration)
Hereinafter, an apparatus for predicting the life of a forging die will be described. FIG. 1 shows a block diagram of a forging die life prediction processing apparatus 500 using the invention. The forging die life prediction processing device 500 is a device that performs the forging die life prediction described in the first embodiment, and is configured using a computer. Although not shown in the drawings, the forging die life prediction processing apparatus 500 has a CPU, various storage devices such as a semiconductor memory and a hard disk device, and various interface functions, like a general computer.

  The forging die life prediction processing apparatus 500 has the following functional units configured in software. That is, the forging die life prediction processing apparatus 500 includes a wear amount acquisition unit 501, a burr movement amount calculation unit 502, a (burr movement amount × number of shots) calculation unit 503, a relational expression calculation unit 504, and a life wear amount acquisition unit. 505, a life shot number calculation unit 506 is provided.

  The wear amount acquisition unit 501 acquires a measured value of the wear amount of the flash surface of the forging die generated in the forging process. Here, the target of acquisition of the wear amount is a portion of the flash surface with the most wear as indicated by reference numeral 305 in FIG. Note that the wear amount is measured using, for example, a three-dimensional digitizer. The burr movement amount calculation unit 502 calculates the movement amount of burrs generated during forging on the flash surface from which the wear amount is acquired by computer simulation. This process is performed using commercially available simulation software. The movement amount of the burr is expressed by a value (し た Vdt) obtained by integrating the moving speed V with the moving time. Since the amount of calculation of this simulation is larger than that of other processes, it is also possible to perform this calculation with an external computer and input the result to the forging die life prediction processing apparatus 500.

  The (burr movement amount × number of shots) calculation unit 503 performs a process of multiplying ∫Vdt, which is the burr movement amount calculated by the burr movement amount calculation unit 502, with the number of shots when the corresponding wear amount is obtained. . The relational expression calculation unit 504 calculates a relational expression between (burr movement amount × number of shots) shown in FIG. 4 and the actual wear amount acquired by the wear amount acquisition unit 501. This relational expression is expressed by the following equation (1).

Ｗ：実測した磨耗量、Ａ：比例定数、∫Ｖｄｔ：算出したバリの移動量、Ｓ：ショット数

W: Measured wear amount, A: Proportional constant, ∫ Vdt: Calculated burr movement amount, S: Number of shots

  The life wear amount acquisition unit 505 acquires the wear amount W allowed for the forging die as a target. The required accuracy of the mold is determined, and when the amount of wear reaches a certain level, this accuracy cannot be obtained and the service life is reached. From this, it is possible to estimate the wear amount W allowed for the forging die as a target. The life shot number calculation unit 506 calculates the number of shots S that reach the life of the forging die by substituting the allowable wear amount W acquired by the life wear amount acquisition unit 505 into Equation 1.

(Example of processing)
An example of operation | movement of the lifetime prediction processing apparatus 500 of the forging die shown in FIG. 5 is shown. FIG. 6 is a flowchart showing an example of a procedure of operations performed by the forging die life prediction processing apparatus 500. A program for executing the process shown in FIG. 6 is stored in a data storage unit (not shown) (for example, a hard disk device) provided in the forging die life prediction processing apparatus 500 and read out to an appropriate storage area. This is executed by a CPU (not shown) included in the forging die life prediction processing apparatus 500. The operation program may be stored in an appropriate external storage medium and provided from there.

  Hereinafter, the process of FIG. 6 will be described by taking the case of the forging die illustrated in FIG. 3 as an example. When the life prediction process is started (step S601), the actually measured wear amount of the flash surface 302 in the portion indicated by reference numeral 305 in FIG. 3 indicating the maximum wear amount is acquired (step S602). This amount of wear is measured using a three-dimensional digitizer and is obtained at a plurality of different forging conditions. In step S602, for example, the measured amount of wear on the flash surface when forging 500 shots, 1000 shots, 2000 shots, and 3000 shots in each of the crushing die, the rough die, and the finishing die is obtained.

  Next, using the simulation software, a burr movement amount (X = バ リ Vdt) of the work material during the forging process in the portion 305 is calculated (step S603). This calculation is performed for each forging condition of a plurality of wear amounts acquired in step S602. In the above example, the amount of movement of burrs (X = ∫Vdt) during forging of each of the crushed die, the rough die, and the finish die is calculated.

  Next, based on the value of X = ∫Vdt calculated in step S603 and the number of shots S under the condition where the corresponding wear amount W is acquired, the proportionality constant A in the equation 1 is calculated (step S604). For example, in the above example, the product of X = ∫Vdt and 500 shots, 1000 shots, 2000 shots, and 3000 shots in each of the crushing type, the rough type, and the finishing type is obtained, and these values are calculated on the horizontal axis. On the other hand, by plotting the measured amount of wear of the flash surface in the crushing type, roughing type, and finishing type in each of the 500 shots, 1000 shots, 2000 shots, and 3000 shots as values on the vertical axis, FIG. And a proportionality constant A of Formula 1 is calculated from the slope of the straight line graph.

  Next, the wear amount W that becomes the life under the forging conditions is acquired (step S605), and the number of shots S until the forging die reaches the end of the life is obtained by substituting this W into Equation 1. Is calculated (step S606), and the process is terminated (step S607).

  According to the above processing, if the amount of wear of the forging die that becomes a limit is known regardless of the type of die such as a crushing die, a rough die, and a finishing die, the amount of wear is reached based on Equation 1. Is obtained by a simple calculation. For example, when preparing a mold with a modified precision, it is possible to predict the limit number of shots until the mold reaches the end of its life by performing the above process without newly acquiring data. it can.

  The present invention can be used for forging techniques.

  DESCRIPTION OF SYMBOLS 11 ... Forging die (upper die), 11a ... Flash surface, 12 ... Forging die (lower die), 12a ... Flash surface, 13 ... Work material, 14 ... Burr produced during forging, 100 ... Crankshaft 101 ... Journal shaft part, 102 ... Arm part, 103 ... Crank pin part, 300 ... Forging die, 301 ... Cavity part, 302 ... Flash face, 303 ... Drilling face, 304 ... Spacing holding part, 305: A portion where the wear on the flash surface is large.

Claims (9)

A method for predicting the life of a forging die,
Calculate the number of shots that can withstand the use of the forging die based on the relationship between the product of the amount of burrs and the number of shots during forging and the amount of wear of the portion of the forging die that contacts the burrs. A method for predicting the life of a forging die characterized by The amount of movement of the burr is obtained by simulation,
The method for predicting the life of a forging die according to claim 1, wherein the wear amount is obtained by actual measurement.   The method for predicting the life of a forging die according to claim 1 or 2, wherein a portion with the greatest wear in the forging die is selected as the portion in contact with the burr.   The method for predicting the life of a forging die according to any one of claims 1 to 3, wherein a plurality of parts are selected as a part from which the amount of movement of the burr is acquired and a part in contact with the burr.   The relationship between the product of the amount of burrs and the number of shots at the time of forging and the amount of wear of the portion of the forging die that contacts the burrs is directly proportional. The method for predicting the life of a forging die according to any one of the above items.   The forging die is constituted by a pair of dies, and the material to be processed is forged between the pair of dies, and is sandwiched between flash surfaces provided in the pair of dies at the time of forging. 6. A method for predicting the life of a forging die according to any one of claims 1 to 5, wherein burrs are generated. As the forging die, a plurality of types having different processing accuracy for the same work material and different wear amounts as a guide for the life are prepared,
The relationship between the product of the amount of burrs and the number of shots at the time of forging and the amount of wear at the portion of the forging die that contacts the burrs is substantially the same in the plurality of types of forging dies. The method for predicting the life of a forging die according to any one of claims 1 to 6. A forging die life prediction device,
Calculation to calculate the number of shots that can withstand the use of the forging die based on the relationship between the product of the amount of burrs and the number of shots during forging and the wear amount of the portion of the forging die that contacts the burrs. A forging die life prediction apparatus comprising a portion. A program for causing a computer to read and predict the life of a forging die,
Computer
Calculation to calculate the number of shots that can withstand the use of the forging die based on the relationship between the product of the amount of burrs and the number of shots during forging and the wear amount of the portion of the forging die that contacts the burrs. A program characterized by functioning as a means.

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