JP2009289018A - Method for predicting upset shape of circular forging - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a trial time and reduce defectives in upsetting circular forgings. <P>SOLUTION: A method for predicting an upset shape of a circular forging has a first step of computing a predetermined number of relationships between a diameter and height in upset forging by a finite element method about each of a plurality of models of circular material, a second step of computing a predetermined number of relationships between a diameter expansion rate and an upsetting rate of corresponding preforms from the diameter-height relationships, a third step of performing polynomial approximation using the predetermined number of diameter expansion rates and upsetting rates to compute a prediction formula about each of the plurality of models of circular material, and a fourth step of selecting the most reliable approximation formula from the plurality of prediction formulae. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for predicting the upset shape of a circular forged product, and more particularly to a method for predicting the upset shape of a circular forged product that enables efficient setting of the upset height by predicting the upset diameter. It is.

  Forging of forged products with a circular outer diameter (hereinafter simply referred to as “circular forged products”), such as disc-shaped or annular steel forged products such as wheels, gears and rings, or wasteland as intermediate products, Is subjected to several steps of forging to form a desired shape. For example, in the waste wheel forming of a wheel, a columnar material is heated, volume distribution in the radial direction is performed by forging in the first step, and the rough shape of the product is formed by forging in the second step. In the forging of an annular product such as a ring, first, upsetting forging of a material is performed as a wasteland forming process. The waste land thus obtained is finished into a product shape by rolling or finish forging.

  When the shape accuracy of the wasteland in the wasteland processing stage is inferior, it is difficult to completely remove it in the subsequent rolling or finish forging, and as a result, the dimensional accuracy of the product is impaired, resulting in a quality defect. Further, in order to compensate for the lack of fullness, measures such as increasing the final machining allowance are taken, but this causes problems such as an increase in yield loss. Therefore, it is important to improve the dimensional accuracy of the wasteland.

For example, in Patent Document 1, in a forging method in which a circular material is squeezed in the axial direction using upper and lower molds that do not have side walls that restrain the side surface of the workpiece, the squeezing is performed halfway in the axial direction or down to the bottom dead center. At the time, the upper and lower surfaces of the work piece are restrained with upper and lower molds, and the side wall of the work piece is pressed using the side pressing tool to correct the uneven thickness that occurs during the rough ground forming, A forging method of a circular forged product that has made it possible to obtain a wasteland having a uniform shape in the direction is disclosed.
JP 2002-35881 A

  Conventionally, when determining the rough ground diameter (upsetting diameter) in the first step (upsetting process) of the vertical forging press, the spacer adjustment is performed several times (2 to 3 times) at the time of trial production before production, Through repeated trial and error, the relationship between the upsetting rate and the upsetting diameter was obtained, the upsetting rate was determined, and the dimensional accuracy of the wasteland was improved. Therefore, trial production time loss and trial production NG occurred.

  In addition, according to the method of Patent Document 1, it is possible to obtain a rough land having a uniform shape in the circumferential direction, but a plurality of types of side pressing tools are required as the upsetting diameter is changed. Therefore, the cost of the mold rises, and work such as setup change according to the product becomes necessary.

  The present invention has been made to solve such a conventional problem, and is intended to provide a method for predicting the upsetting shape of a circular forged product that can shorten the trial production time and increase the yield by reducing NG products. It is.

  The invention according to claim 1 of the present application relates to a first step of obtaining a predetermined number of relationships between a diameter and a height during upsetting forging for each of a plurality of types of circular materials by a finite element method, From the relationship, the second step of obtaining a predetermined number of the relationship between the diameter expansion rate and the upsetting rate of the corresponding wasteland, and using a predetermined number of diameter expansion rate and upsetting rate, polynomial approximation, The upset shape of a circular forged product, comprising: a third step for obtaining a prediction formula for each of the circular materials of the type, and a fourth step for selecting the most reliable prediction formula from a plurality of prediction formulas. This is a prediction method.

  According to the upset shape prediction method for a circular forged product of the present invention, CAE analysis is performed using upset data that is currently known, and the workpiece height and workpiece outer diameter at the time of upsetting are approximated from the obtained analysis results. By obtaining a curve and creating a prediction formula, it is possible to efficiently set the upsetting height, thereby reducing the number of times of rough land trial production, shortening trial production time, and increasing yields by reducing NG products.

  Hereinafter, a method for predicting the upset shape of a circular forged product according to an embodiment of the present invention will be described in detail with reference to the drawings.

  Fig.1 (a) is a front view which shows the shape of the workpiece | work before an upsetting process. A workpiece 1 having a substantially cylindrical shape has a workpiece diameter φA and a workpiece height B. The workpiece diameter φA and the workpiece height B have different numerical values depending on the materials and types used.

  FIG.1 (b) is a front view which shows the shape of the wasteland after upsetting. The wasteland 2 having a substantially disk shape has a shape of a wasteland diameter φC and a wasteland height D. The wasteland diameter φC and the wasteland height D are different values depending on the work to be used and machining conditions.

  As shown in FIG. 1, by upsetting, the workpiece 1 having a diameter φA and a height B is pressed in the vertical direction to become rough ground, the height is compressed from B to D, and the diameter is from φA. It will be expanded to φC.

  Here, C / A is defined as the diameter enlargement ratio Y, and (BD) / B is defined as the upsetting ratio X.

(CAE analysis)
The shape of the workpiece 1 is converted into CAD data and input to a computer, and then forging is simulated by the finite element method. As input data for the CAE analysis, in addition to the shape of the workpiece 1, there are the temperature of the material and the lubrication state (friction state) between the mold and the workpiece 1.

In the CAE analysis, it is possible to obtain information on the wasteland diameter φC and the wasteland height D during the upsetting process. Therefore, (C ₁ , D ₁ ), (C ₂ , D) for one workpiece 1. ₂ ),..., (C _n , D _n ), any n pieces of CAE analysis data can be obtained.

In the present embodiment, (C _n , D _n ) is obtained by CAE analysis, but it is also possible to obtain (C _n , D _n ) by actual measurement, for example. However, in order to obtain information on (C _n , D _n ) by actual measurement, it is necessary to change the press setting and adjust the die, which requires a huge amount of time. The advantage of the CAE analysis of the present embodiment is that the examination on the computer is possible without actually preparing and moving the machine / mold.

(Approximate curve)
First, from the CAE analysis data (C _n , D _n ), the relationship between the diameter expansion rate Y (= C / A) and the upsetting rate X (= (BD) / B) is arbitrarily determined by n CAE analyzes. Calculate according to data. That is, n relationships of (X ₁ , Y ₁ ), (X ₂ , Y ₂ ),..., (X _n , Y _n ) can be obtained for one workpiece 1.

Table 1 shows the CAE analysis of workpieces with workpiece diameter φA of 90 mm and workpiece height B of 150 mm to obtain CAE analysis data (C _n , D _n ), and the relationship between upsetting ratio X and diameter expansion ratio Y (X It is a figure which shows the result of having calculated _| required _n , Yn).

Then, polynomial approximation is performed based on these n pieces of (X _n , Y _n ) data to create a prediction formula.

  In the present embodiment, instead of directly obtaining a prediction formula from the relationship between the wasteland diameter φC and the wasteland height D, a prediction formula is obtained from a dimensionless relationship between the diameter expansion rate Y and the upsetting rate X, and the wasteland The diameter φC and the wasteland height D are predicted. This is because it is necessary to plot and evaluate the results under several tens of conditions on the same graph in order to obtain the prediction formula.

  The prediction formula can be expressed as follows. In the present embodiment, polynomial approximation is performed using a quartic equation.

(Formula 1)
Y = aX ⁴ −bX ³ + cX ² + dX + e
Y is the diameter expansion rate (C / A)
X is the upsetting rate ((BD) / B)

  The reason why the quaternary expression is used is that accurate approximation cannot be performed if the expression is a first to third order expression. The reason why the quartic expression is not higher than the fifth order expression is that the fourth order polynomial expression This is because it has been found that approximation can be sufficiently approximated.

FIG. 2 is a diagram illustrating a result of creating a prediction formula by performing polynomial approximation based on the (X _n , Y _n ) data in Table 1. The prediction formula is (Formula 2).
Y = 0.0000000516X ⁴ -0.0000056679X ³ + 0.0002701085X ² + 0.0039011020X + 1.0173325299
It became.

The method for obtaining the prediction formula for a single type is as described above, but in reality, the workpiece diameter φA and the workpiece height B of the workpiece 1 differ depending on the product number and type to be forged. Therefore, in this embodiment, each breed _W 1 to _W-m of the workpiece 1, the relationship of the workpiece diameter and workpiece height _{(A 1, B 1),} (A 2, B 2), ···, ( A _m , B _m ) are input as the shape data of the work 1, and CAE analysis is performed. Accordingly, (X ₁ , Y ₁ ) to (X _n , Y _n ) are obtained for each of the workpieces W _{1 to} W _m . Then, a prediction formula is obtained for each of the workpiece types W _{1 to} W _m , and as a result, a plurality of m prediction formulas are obtained.

  The most reliable prediction formula is derived based on a plurality of m prediction formulas. As a result, it is possible to derive a transfer processing prediction formula that does not depend on the workpiece type.

  Table 2 shows the shape of the workpiece 1 (first and second rows in the table), and the measured value of the shape of the wasteland 2 when the workpiece 1 is upset (third and fourth rows in the table). Predicted values of rough land length based on the most reliable approximation formula (before correction) (columns 5 and 6 in the table), and predicted values of rough ground length based on the most reliable approximation formula (after correction) (seventh in the table) Column and column 8).

  When the measured values (third and fourth columns) are compared with the predicted values (fifth and sixth columns), it can be seen that there is a slight error. This is because the prediction formula obtained above is based on the result of CAE analysis to the last, and may be different from the actual value.

  Moreover, when performing an actual forging, if the outer diameter after upsetting is too large, there may be a problem that the die does not enter the next process. In this case, since the workpiece cannot be used, it is necessary to estimate the size obtained by the prediction formula to be smaller. Therefore, in this embodiment, the error in the prediction formula is incorporated as a correction value of 3 mm.

  The eighth column in Table 2 represents numerical values obtained by incorporating a correction value of 3 mm into the predicted value of the rough land length. The actual measurement value (fourth column) and the predicted value (eighth column) almost coincide with each other, and the validity of the upset shape prediction method for the circular forged product of this embodiment has been proved.

  As described above, according to the upset shape prediction method of the circular forged product of the present embodiment, the CAE analysis using the upset data that can be grasped at present is performed, and the workpiece height at the time of upsetting is obtained from the obtained analysis result. By calculating the approximate curve of the outer diameter of the workpiece and creating a prediction formula, the number of times of trial production on the rough ground is reduced, and it is possible to shorten the trial production time and increase the yield by reducing NG products.

It is a front view which shows the shape of the workpiece | work before upsetting, and the shape of the wasteland after upsetting in the upsetting shape prediction method of the circular forged product of this embodiment. Table 1 (X _{n, Y n)} based on the data subjected to polynomial approximation is a diagram showing a result of creating a prediction equation.

Claims (1)

For each of a plurality of types of circular materials, a first step of determining a predetermined number of diameters and heights during upsetting forging by a finite element method,
From the relationship between the diameter and the height, a second step for determining the predetermined number of the relationship between the diameter expansion rate and the upsetting rate of the corresponding wasteland,
A third step of performing a polynomial approximation using the predetermined number of the diameter expansion ratio and the upsetting ratio, and obtaining a prediction formula for each of the plurality of types of circular materials;
A fourth step of selecting the most reliable prediction formula from the plurality of prediction formulas and making the prediction formula independent of the type of circular material;
A method for predicting the upset shape of a circular forged product, comprising:

Images