JP3752907B2 - Impression placement determination method in forging die - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for determining an arrangement of a plurality of impressions corresponding to a product shape in a forging die.
[0002]
[Prior art]
When determining the placement of multiple impressions corresponding to the product shape in a forging multi-cavity mold, the placement of impressions is determined by trial and error based on experience so that the product manufacturing cost is minimized. It was.
[0003]
In addition, a technique for reducing the manufacturing cost by improving the material yield has been proposed. For example, Japanese Patent Application Laid-Open No. 7-148542 describes a forging metal material arrangement line position calculating device and a forging impression position calculating device for increasing the material yield. Japanese Patent Application Laid-Open No. 7-265993 describes a forging method that can increase the material yield even when the impression shape is asymmetric, such as two-piece.
[Problems to be Solved by the Invention]
[0004]
However, when the arrangement of impressions is determined by trial and error based on experience as described above, the determined arrangement of impressions is not always the optimum arrangement with the lowest manufacturing cost.
[0005]
In addition, considering the breakdown of product manufacturing costs, the proportion of mold costs is large. Therefore, even if the arrangement of the impressions in the forging die is determined so that the material yield is improved, if the life of the forging die is shortened thereby, the improvement in the material yield does not directly reduce the manufacturing cost. Become. Moreover, if the increase in the manufacturing cost due to the decrease in the life of the forging die becomes larger than the decrease in the manufacturing cost due to the improvement in the material yield, the manufacturing cost increases on the contrary. Therefore, it was not possible to minimize the manufacturing cost only by improving the material yield.
[0006]
The present invention has been made in the background of the above circumstances, and the object of the present invention is to provide a method capable of determining the arrangement of impressions in a forging die so that the production cost of a product is minimized. is there.
[0007]
[Means for Solving the Problems]
The present inventor has found that the manufacturing cost can be further reduced as compared with the prior art by determining the arrangement of the impressions in the forging die in consideration of not only the material yield but also the die life. The present invention has been made based on such findings.
[0008]
That is, the gist of the present invention for achieving the above object is an impression arrangement determination method for determining the arrangement of a plurality of impressions in a forging die, and (a) a provisional impression of the impression in the forging die. A temporary placement determination step for determining the placement; and (b) a die life determination step for determining the life of the forging die based on a molding load received by the forging die for which the temporary placement of the impression is determined in the temporary placement determination step. And (c) a die cost calculating step of calculating a die cost by dividing the unit price of the forging die stored in advance by the die life determined in the die life determining step, and (d) in the temporary placement determining step, A material cost calculating step for calculating a material cost based on the volume of the material forged by the forging die for which the temporary placement of the impression is determined; and (e) the temporary placement determining step. From the provisional arrangement of the plurality of impressions determined in step S3, the optimum arrangement of the impressions is determined such that the sum of the mold cost calculated in the mold cost calculation step and the material cost calculated in the material cost calculation step is minimized. And an optimal placement determination step.
[0009]
【The invention's effect】
That is, for a plurality of forging dies for which the temporary placement of impressions has been determined in the temporary placement determining step, the die life is determined based on the molding load of the forging die in the die life determining step, and the forging stored in advance in the die cost calculating step The die cost is calculated by dividing the unit price of the die by the die life , and the material cost is calculated based on the volume of the material forged by the forging die in the material cost calculating step. Then, in the optimum arrangement determining step, the one that minimizes the sum of the mold cost and the material cost from the temporary arrangement of the plurality of impressions is determined as the optimum arrangement of the impressions. In other words, since the placement of impressions is determined in consideration of not only the material cost but also the mold cost, the manufacturing cost of the product can be reduced compared to the case where the placement of the impression is determined only by considering the material cost. .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, taking as an example the case of designing a two-piece forging die in order to manufacture two connecting rods 10 simultaneously.
[0011]
FIG. 1 is a flowchart for explaining a main part of a method for determining the relative optimum arrangement of two impressions corresponding to the shape of the connecting rod 10 in the forging die. In this embodiment, calculation is performed using a program stored in advance on a three-dimensional CAD system.
[0012]
As shown in FIG. 1, first, a two-placement model 14 is created (step ST1). The two-piece arrangement model 14 is a solid model that indicates the relative arrangement of the two connecting rods 10 based on the shape data of the connecting rods 10 input in advance into the three-dimensional CAD system. 2 to 5 show plan views of two different arrangement models 14a to 14d.
[0013]
As shown in FIG. 2, the intersection of the straight line L ₁ representing the end of the connecting rod 10 on the large diameter side and the straight line L ₂ that bisects the connecting rod 10 is P ₁ , the small diameter center is O ₁ , and the intersection of the two connecting rods 10. the center of the center or two deployment model 14 of the straight line L ₃ connecting the between P ₁ and O _2, a point where a perpendicular line from the center O ₂ to the straight line L ₂ intersects the straight line L ₂ When P _2, 2 arranged The model 14 has a distance A from the intersection P ₁ to the intersection P ₂ (hereinafter referred to as the vertical dimension, this direction is referred to as the vertical direction) and a distance B from the center O ₂ to the intersection P ₂ (hereinafter referred to as the horizontal dimension). Okay, this direction is called the horizontal direction). Therefore, the two-placement model 14 is created by actually inputting the vertical dimension A and the lateral dimension B using a prestored program that can create the two-placement model 14.
[0014]
Next, the shortest distance D of the two arrangement model 14 created in step ST1 is calculated (step ST2). The shortest distance D is a distance at which the distance between the two connecting rods 10 is the shortest, and the distance that is spatially shortest is calculated. 2 to 5 show which position is the shortest distance D, respectively.
[0015]
Subsequently, the shortest distance D calculated in step ST2 it is determined whether a predetermined object minimum distance D _M (step ST3). The shorter the distance between the two connecting rods 10, that is, the shorter the shortest distance D, the fewer the internal burrs formed between the connecting rods 10. Therefore, the material yield is improved. The strength of the deburring die for removing slabs decreases. That is, the target shortest distance _DM is a distance that can shorten the distance between the two connecting rods 10 within a range in which the strength of the deburring die is allowable, and is determined empirically or based on strength analysis. Incidentally, the purpose shortest distance D _M may be a constant value irrespective of the relative arrangement of the two connecting rods 10 (e.g. 10 mm), the value may be different for each relative arrangement.
[0016]
If the determination in step ST3 is negative, the process returns to step ST1 and the value of at least one of the vertical dimension A and the horizontal dimension B is input again. On the other hand, if the determination in step ST3 is affirmative, the relative arrangement of the two connecting rods 10 indicated by the two arrangement model 14 created in step ST1 is determined as a temporary arrangement of impressions in the forging die. Therefore, step ST3 corresponds to a provisional arrangement determination step. When the temporary arrangement can be determined, the subsequent steps are executed.
[0017]
That is, if the determination in step ST3 is affirmed, next, a load receiving area S1 that approximates a range in which the forging die for which the temporary placement of the impression is determined in step ST3 receives the load is calculated (step ST4). . Specifically, the projected area in the range shown by the oblique lines in FIG. 6 is calculated as the load receiving area S1. That is, the projected area of the two connecting rods 10, the projected area of the inner burr 18 surrounded by the semicircle 16 and the straight line L ₁ forming the outer shape on the large diameter side of the connecting rod 10, and the straight lines L ₁ and L ₂ The total area of the projected areas of the intermediate burrs 20 formed between the two connecting rods 10 in the enclosed rectangular range is the load receiving area S1.
[0018]
Next, the molding load W (kg) received by the forging die is calculated (step ST5). The molding load W can be calculated by applying a unit molding load for each product (for example, connecting rod) obtained experimentally to the load receiving area S1.
[0019]
Next, the mold life is determined (step ST6). That is, step ST6 corresponds to a mold life determination process, and the mold life is determined from the molding load W actually calculated in step ST5, using a predetermined relationship between the molding load W and the mold life. For reference, when the molding load W increases, the product accuracy deteriorates due to mold wear, and the material is easily seized to the mold, so that the mold life is shortened. FIG. 7 is a schematic diagram showing the relationship between the molding load W and the mold life. The mold life is shortened as the molding load W increases, and abruptly shortens when the molding load W is exceeded. Therefore, when the load receiving area S1 is minimized, the mold life can be maximized.
[0020]
Next, the mold cost is calculated (step ST7). That is, step ST7 corresponds to a mold cost calculation process. The die cost is the cost of the forging die required to manufacture one product (in this embodiment, the connecting rod 10), and the unit cost of the forging die stored in advance is divided by the die life determined in step ST6. Can be calculated by
[0021]
Next, the maximum cross-sectional area S2 _MAX in the lateral direction is calculated for the workpiece after the forging process using the forging die for which the temporary placement of the impression has been determined in step ST3 (step ST8). That is, the workpiece after the forging process, the cross-sectional area S2 calculated cut perpendicular any plane in parallel and connecting rod 10 to the straight line L _1, the largest cross-sectional area S2 and the maximum cross-sectional area S2 _MAX. In addition, this cross-sectional area S2 is a workpiece in a state excluding an outer burr (not shown) protruding outside the connecting rod 10 (that is, a portion constituted by two connecting rods 10, an inner burr 18, and an intermediate burr 20). Is the cross-sectional area. That is, it is the cross-sectional area of the work corresponding to the projection portion of step ST4.
[0022]
Next, the material diameter r is calculated (step ST9). A raw material is a cylindrical metal material used for forging. The raw material is subjected to a margin process in a margin process described later, and then placed between the upper and lower forging dies so as to be parallel to the straight line L ₃ shown in FIG. 2 and forged. Therefore, first, the cross-sectional area S3 when the material is cut along a plane perpendicular to the axis is determined, and the material diameter r is calculated from the cross-sectional area S3. The cross-sectional area S3 of the above materials, the maximum cross-sectional area S2 _MAX determined in the step ST8, is calculated by multiplying a predetermined value α (α> 1) that is experimentally determined in advance. Then, the radius r of the material is determined so that the calculated cross-sectional area S3 is obtained.
[0023]
Next, the pitch T (distance) between the centers of the large diameter ends of the two connecting rods 10 is calculated for the two arrangement model 14 determined in step ST3 (step ST10). The large-diameter end portion around the center point of the end portion of the large diameter side of the connecting rod 10 that is, the intersection point P _1. Since the pitch T between the large-diameter end center P ₁ is experimentally equal to the length of the workpiece after the squeezing process described later, the pitch T between the large-diameter end part centers P ₁ is the work after the squeezing process. Represents the length of
[0024]
Next, the workpiece after forging process using a forging die having determined the temporary arrangement of impressions the step ST3, the calculating the change in cross-section of the cross-sectional area S4, and cut into a straight line L ₃ perpendicular plane shown in FIG. 2 (Step ST11). In addition, this cross-sectional area S4 is also a cross-sectional area of the work in a state in which an external burr protruding outside the connecting rod 10 is excluded. A curve C ₁ shown in FIG. 8 indicates the relationship between the distance from the center O ₂ of the two-placement model 14 to the point where the cut surface intersects the straight line L ₃ and the size of the cross-sectional area S4 at the cut surface. A curve C ₂ shown in FIG. 8 indicates the cross-sectional area S5 of the workpiece after the margin process calculated in the subsequent step ST12.
[0025]
Next, the shape of the workpiece after the margin process is determined, and the volume V ₁ of the margin formed by the margin process is calculated (step ST12). The margin process is an intermediate process in which a margin is formed in advance on the workpiece before the forging process in order to improve the material yield. FIG. 9 is a cross-sectional view of a workpiece obtained by squeezing a cylindrical material in a longitudinal direction along a plane passing through the axis. As shown in FIG. 9, the recess at the center is the threshold 22, and the volume of the recess recessed in the limit process is the volume V ₁ of the threshold 22. In addition, the small recesses 24 provided on the left and right sides of the margin 22 are formed by pressing the material to prevent the material from floating when the margin 22 is formed on the material in the margin process.
[0026]
The cross-sectional area S5 when the work after the cutting process is cut in the same cross section as the work after the forging process cut in step ST11 must be larger than the cross-sectional area S4 of the work after the forging process. . Work after forging step, as shown in FIG. 8, the cross-sectional area S4 are near the center O ₂ of the two placement model 14 is small, the distance e from the center O ₂ is maximized in e ₁ in the vicinity of 40 mm. Accordingly, the cross-sectional area S5 of the workpiece after staking becomes a predetermined multiple (for example, 1.1 times) of the cross-sectional area S4 at the distance e ₁ , and gradually decreases linearly toward the center O ₂ direction. ₂ is determined to be a predetermined multiple (for example, twice) of the cross-sectional area S4. Accordingly, the hatched range in FIG. 8 is the marginal volume V ₁ .
[0027]
Next, the volume V ₂ of the material is determined (step 13). The volume V ₂ of the material was calculated in Step ST12 from the volume of the cylinder that can be calculated using the material diameter r calculated in Step ST9 and the workpiece length T after the margin process calculated in Step ST10. It can be calculated by subtracting the Segiri volume V _1. That is, it can be calculated by the following formula 1.
(Formula 1) V ₂ = (πr ² × T) −V ₁
[0028]
Next, the material cost required for manufacturing one connecting rod 10 is calculated based on the volume V ₂ of the material calculated in step ST13 (step ST14). That is, first, the material weight is calculated by multiplying the material volume V ₂ calculated in step ST13 by the material density, and the material weight is multiplied by a predetermined price per unit weight of the material. To calculate the material cost. Therefore, step ST14 corresponds to a material cost calculation process.
[0029]
Next, it is determined whether the total cost of the mold cost calculated in step ST7 and the material cost calculated in step ST14 is the minimum (step ST15). If it is determined that the total cost is not the minimum, the process returns to step ST1 to set a different two-placement model 14 and similarly calculate the total cost of the mold cost and the material cost. By repeating this, the total cost is calculated for a plurality of two-placement models 14. On the other hand, when it is determined that the total cost is the minimum, the two-placement model 14 at that time is determined as the optimum placement. Therefore, step ST15 corresponds to an optimum arrangement determining step.
[0030]
For example, if the shortest distance D is a constant value, if one of the vertical dimension A and the horizontal dimension B is determined, the other is determined to be one. Accordingly, as shown in FIG. 3, a large diameter central connecting rod 10 and O _3, and the large-diameter center O ₃ is parallel to the street lines L ₁ straight line L _4, the straight line L ₄ and the straight line L ₂ Assuming that the intersection point is P ₃ and the distance from the large diameter center O ₃ to the intersection point P ₃ is the longitudinal length a of the two placement model 14, the two placement model 14 can be represented only by the longitudinal length a. (In the connecting rod 10, the portion on the end side of the straight line L ₄ is a portion provided as a margin for processing.) Therefore, the relationship between the longitudinal length a and the total cost is plotted on a graph, If the longitudinal length a that minimizes the total cost is determined from the graph, it is possible to easily determine the optimal two-placement model 14, that is, the optimal placement of impressions. FIG. 10 is a graph showing the relationship between the longitudinal length a of the two-placement model 14 and the total cost, and the total cost is minimum at the longitudinal length a ₁ . However, in practice, several points constituting the curve shown in FIG. 10 are obtained, and when the total cost shows the smallest value among the points, the optimum two-placement model 14 is determined. . In FIG. 10, a ₀ is the length from the large diameter center O ₃ to the small diameter center O ₁ of the connecting rod 10.
[0031]
Incidentally, in the same manner as in FIG. 10, to represent the relationship between the longitudinal length a in the graph only for material costs calculated in the step ST14 is as shown in FIG. 11, the longitudinal length a is shorter than a ₁ a _{In 2} the material cost is minimal. However, in the relationship between only the mold cost and the longitudinal length a shown in FIG. 12, the mold cost is minimum at a ₃ where the longitudinal length a is longer than a ₁ . As a result, the total cost of the mold costs and material costs is the longitudinal length a becomes minimum at a _1.
[0032]
As described above, according to the present embodiment, a plurality of forging dies for which the temporary placement of impressions has been determined in the temporary placement determining step (ST3) is based on the molding load W of the forging die in the die life determining step (ST6). The die life is determined, the die cost is calculated based on the die life in the die cost calculating step (ST7), and the material cost calculating step (ST14) is based on the volume V ₂ of the material to be forged by the forging die. Calculate the material cost. Then, in the optimum arrangement determination step (ST15), the optimum arrangement of impressions is determined from the temporary arrangement of a plurality of impressions, which minimizes the total cost of the mold cost and the material cost. That is, since the arrangement of the impression is determined in consideration of not only the material cost but also the mold cost, the manufacturing cost of the connecting rod 10 can be reduced as compared with the case where the arrangement of the impression is determined only in consideration of the material cost. it can.
[0033]
As mentioned above, although one Example of this invention was described based on drawing, this invention can be implemented also in an aspect different from the said Example.
[0034]
For example, in the foregoing embodiment, in order to calculate the material diameter r, the cross-sectional area S3 of the material is calculated by multiplying the maximum cross-sectional area S2 _MAX in the lateral direction of the workpiece after the forging process by a predetermined value α. since the material is placed in parallel with the straight line L _3, the workpiece after the forging process on the basis of the cross-sectional area of a cross section cut along a plane perpendicular to the straight line L _3, also determine the material diameter r Good.
[0035]
Moreover, although the above-mentioned Example demonstrated the case where the forging die which takes the two connecting rods 10 was designed, this invention is applicable also in order to design the forging die which manufactures products other than a connecting rod. Further, the number of products that are simultaneously forged may be three or more. 13 and 14 are plan views of a two-placement model of a product other than the connecting rod. FIG. 13 is a plan view of a two-placement model of a knuckle arm, and FIG. It is a top view of an individual arrangement model. In FIGS. 13 and 14, the position of the shortest distance D is shown, and the range of the load receiving area S1 is shown by hatching.
[0036]
In the above-described embodiment, it is determined whether or not the shortest distance D of the two-placement model 14 created by inputting the vertical dimension A and the horizontal dimension B in step ST1 is a predetermined target shortest distance D _M. (Step ST3) When the shortest distance D is not the determined shortest distance D _M , the vertical dimension A or the horizontal dimension B is re-input, but when the target shortest distance D _M is a constant value, the vertical dimension A and the horizontal dimension If any one of the dimensions B is determined, the other is determined to be one. Therefore, if only the vertical dimension A or the horizontal dimension B is input, the other may be automatically calculated.
[0037]
Further, in the above-described embodiment, the model having the minimum total cost of the mold cost and the material cost among the two arrangement models 14 determined by inputting the vertical dimension A and the horizontal dimension B is optimal. As described above, if the target shortest distance D _M is determined, the two-placement model 14 is determined to be one if either the vertical dimension A or the horizontal dimension B is determined. Therefore, the vertical dimension A or the horizontal dimension B, or a numerical value (for example, the longitudinal length a) instead of them is automatically changed, and a plurality of two-placement models 14 are automatically created. A model with a low total cost may be determined as the optimal placement.
[0038]
Further, in the above-described embodiment, if the longitudinal length a is determined, the two arrangement model 14 is determined to be one. Therefore, as shown in FIG. 10, the relationship between the longitudinal length a and the total cost is plotted on a graph. From the graph, the longitudinal length a that minimizes the total cost has been determined, but the arrangement of the two arrangement models 14 such as the longitudinal dimension A, the lateral dimension B, or the large end-to-end pitch T is determined as one. A numerical value that can be used may be used instead of the longitudinal length a.
[0039]
In the above-described embodiment, the intermediate burr 20 is a range formed between the two connecting rods 10 in a rectangular range surrounded by the straight line L ₁ and the straight line L ₂ , but is a range where a load is received between products. As long as is approximated, a range determined by a different method may be used. For example, as shown in FIG. 4, a range surrounded by a straight line L ₅ parallel to the straight line L ₂ and the two connecting rods 10 passing through the widthwise end of the connecting rod 10 may be an intermediate burr 20. Alternatively, the distance from the center O ₂ of the two-arrangement model 14 is _two points at the farthest from the center O ₂ of the two-arrangement model 14 on the small-diameter side of the one connecting rod 10 and the two most on the large-diameter side of the other connecting rod 10 A range surrounded by a line connecting a point far from the center O _{2 of the} arrangement model and the outline of the connecting rod 10 may be the intermediate burr 20.
[0040]
What has been described above is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit of the present invention.
[Brief description of the drawings]
FIG. 1 is a flowchart for explaining a main part of a method for determining a relative optimal arrangement of two impressions corresponding to the shape of a connecting rod in a forging die.
FIG. 2 is a plan view of a two-rod connecting model.
FIG. 3 is a plan view of a two arrangement model of connecting rods, showing a different arrangement from FIG. 2;
FIG. 4 is a plan view of a two arrangement model of connecting rods, showing a different arrangement from FIGS. 2 and 3;
FIG. 5 is a plan view of a two connecting rod arrangement model, showing an arrangement different from that of FIGS. 2, 3, and 4;
FIG. 6 is a diagram illustrating a range of a load receiving area S1.
FIG. 7 is a schematic view showing a relationship between a molding load W and a mold life.
FIG. 8 is a diagram illustrating a cross-sectional area of a workpiece after a staking process with respect to a distance from the center of a two-placement model.
FIG. 9 is a cross-sectional view of the workpiece after the cutting process, cut in the longitudinal direction along a plane passing through the axis.
FIG. 10 is a graph showing the relationship between the longitudinal length a of the two-placement model and the total cost.
FIG. 11 is a graph showing the relationship between the longitudinal length a of the two-placement model and the material cost.
FIG. 12 is a graph showing the relationship between the longitudinal length a of the two-placement model and the mold cost.
FIG. 13 is a plan view of a two-arrangement model of knuckle arms.
FIG. 14 is a plan view of a two-arrangement model of lower arms.
[Explanation of symbols]
ST3: Temporary placement determining step ST6: Mold life determining step ST7: Mold cost calculating step ST15: Optimal placement determining step

Claims (1)

An impression arrangement determination method for determining an arrangement of a plurality of impressions in a forging die,
A temporary placement determining step for determining a temporary placement of the impression in the forging die;
A die life determining step for determining a life of the forging die based on a molding load received by the forging die for which the temporary placement of the impression is determined in the temporary placement determining step;
A die cost calculating step of calculating a die cost by dividing the unit price of the forging die stored in advance by the die life determined in the die life determining step;
Based on the volume of the material that is forged by the forging die for which the temporary placement of the impression is determined in the temporary placement determination step, a material cost calculation step that calculates a material cost,
From the temporary placement of the plurality of impressions determined in the temporary placement determination step, the impression having the smallest total of the mold cost calculated in the mold cost calculation step and the material cost calculated in the material cost calculation step is used. And an optimum arrangement determining step for determining the optimum arrangement of the impression arrangement in the forging die.

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