JP2000271674A - Die internal stress analysis method and model die manufacturing method for die internal stress analysis - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To easily, efficiently and accurately analyze the internal stress of a mold in each step of metal plastic working, and efficiently perform appropriate mold design. An elastic deformation range of a model type using a model type made of a continuous body of elastic material such as resin (solid material) and using a model material similar to the deformation characteristic of a metal material as a material to be processed. Within, a simulation experiment according to the actual process of plastic working with the model material is performed, and at an elapse point or a continuous point arbitrarily selected from all the processes, the amount of change in the internal strain or internal stress of the model type is measured. Analyze the measurement results at each measurement point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for analyzing the internal stress of a metal mold used in metal forming such as forging, extrusion and drawing, and a method for manufacturing a model used in a simulation experiment thereof. .

[0002]

2. Description of the Related Art In the production of various molds used in plastic working of metal, it is necessary to design a shape for processing a workpiece with high accuracy and efficiency in each manufacturing process. Conventionally, such a mold design largely depends on the experience and intuition of the engineer, and the mold is actually manufactured for each process,
It was a fact that the mold design was optimized by repeating the work of putting this into an actual process, making a prototype, inspecting the quality of the workpiece, and improving the defects of the mold.

[0003] However, a great deal of labor, time and cost are required to actually produce a mold. In addition, the results of the manufacture and improvement of the mold largely depend on the ability of the engineer, and as a result, trial and error are repeated unnecessarily, and there are many problems in production efficiency.

[0004] The problems that occur in the mold during the plastic working process are caused by unevenness of the stress generated inside the mold, stress exceeding the allowable stress generated at the time of working, and the like. Therefore, as a method of verifying such a stress distribution more practically, a pressure-sensitive paper is attached to the inner surface of a mold or a pressure-measuring pin is attached, and then put into the actual process to change the pigment on the pressure-sensitive paper surface. There is a method in which the stress distribution is detected based on the amount and the pressure change amount of the pressure measuring pin, and the mold is improved based on the stress distribution.

[0005] However, even in such a method, it is still necessary to actually manufacture a mold. Although only the stress on the mold surface is verified here, the stress applied in the actual process is also generated inside the mold, and it is more important to study the distribution of such internal stress. Essential for optimizing mold design.

Therefore, as a method of analyzing the internal stress of the mold and designing the mold in accordance with the actual process, various methods using the finite element method have been studied. In particular, instead of simply applying the finite element method as it is, analysis using the finite element method should take into account various factors in the actual process, such as changes in the thickness and contact area due to deformation of the work material and mold. The method to be performed is described in, for example, JP-A-7-30
Many are disclosed in, for example, US Pat.

[0007]

However, in each of the above methods, when performing analysis by the finite element method, complicated various boundary conditions and other input conditions are required. In particular, the more complicated factors are introduced into the analysis in consideration of the effect of the actual process on the mold, the more complicated and inefficient the calculation process becomes. Therefore, it was difficult to perform such an analysis for each process. Moreover, even with such a complicated analysis method, there may be a case where the result is different from the actual processing result, and in many cases, the stress distribution inside the mold in the actual process cannot be accurately reflected.

Accordingly, an object of the present invention is to analyze the internal stress of a mold simply, efficiently and accurately in each step of metal plastic working, and to efficiently perform appropriate mold design.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have developed a model mold and a material that are not appropriately selected from actual molds and workpieces but are appropriately selected so that the actual machining phenomena can be faithfully reproduced. The present inventors have invented a method of analyzing the internal stress of the above-mentioned model type by producing model workpieces, using them, performing simulation experiments according to the actual process to be analyzed, and using them. The results obtained in this way accurately reproduce the pressure conditions acting on the mold moment by moment as the workpiece is deformed in the actual mold. A distribution similar to the mold internal stress distribution is obtained.

That is, the method for analyzing the internal stress of a mold according to the present invention uses a model mold made of a continuous body of elastic material such as resin (solid material), and uses a model material similar to the deformation characteristic of a metal material as a material to be processed. By using, within the elastic deformation range of the model type, a simulation experiment is performed in accordance with the actual process of plastic working with the model material, and at any lapse point or continuation point selected arbitrarily from all the processes, It is characterized in that the amount of change in internal strain or internal stress is measured, and the measurement result at each measurement point is analyzed. Thus, since the model-type internal stress is actually measured by the simulation experiment and the analysis is performed based on the measurement result, it is possible to easily perform the accurate analysis according to each process. Further, since a model die is used, its production is easier and less expensive than the production of an actual die.

Further, in the method for analyzing the internal stress of a mold inside the model mold according to the present invention, an element capable of detecting a strain or stress, such as a strain gauge or an optical fiber, is embedded at a predetermined position inside the model mold, whereby the internal strain is reduced. It is characterized in that the amount of change is measured and analyzed. In this way, in a simulation experiment according to the actual process, the internal strain of the model type was measured,
Since the analysis is performed based on the measurement results, accurate analysis according to the actual process can be easily performed.

Further, in the method for analyzing the internal stress of a mold inside the model mold according to the present invention, the model mold comprises: a laminated core portion in which a strain gauge or an optical fiber is embedded at a predetermined position inside;
A wedge-shaped inner portion formed in accordance with the shape of the analysis target mold so as to be in close contact with the core portion and to be mechanically continuous. As a result, it is possible to measure the internal strain of the model die by manufacturing only the inner portion of the model die in accordance with the die to be analyzed and using the laminated core portion in common without re-producing it. The effects of improving workability and reducing costs in manufacturing the model mold are obtained.

[0013] In the method for analyzing the internal stress of a mold inside the model die according to the present invention, the model die may include a wedge-shaped cassette part in which a strain gauge or an optical fiber is previously embedded at a predetermined position, and the cassette part is fitted. In a mechanically continuous by a wedge effect, and a main body of a structure capable of fixing a strain gauge or an optical fiber at all predetermined positions inside, and the cassette unit is fitted to the main body unit, In a state where hydrostatic pressure is applied from the outside of the entire model mold, the amount of change in internal strain is measured and analyzed by the strain gauge or the optical fiber. As a result, it is possible to measure the internal distortion of the model type by preparing only the main part of the model type according to the die to be analyzed and using it in common without recreating the cassette part. An effect of improving workability in mold production and reducing costs is obtained.

Further, the method of manufacturing a model mold for analyzing the internal stress of a mold according to the present invention is characterized in that, under atmospheric pressure or reduced pressure, the present agent and a curing agent are placed in a mold in which a strain gauge or an optical fiber is fixed at a predetermined position in advance. It is characterized by injecting a two-part mixed type resin and curing it. This allows
A model that can measure internal strain at a predetermined position can be obtained.

Further, the method for manufacturing a model mold for analyzing the internal stress of a mold according to the present invention is characterized in that a two-pack mixed type resin comprising the present agent and a curing agent is injected under atmospheric pressure or reduced pressure to a predetermined height in a mold. This is once cured or molded into a required shape using an optical molding device, a strain gauge or an optical fiber is fixed at a predetermined position on the upper surface, and then the resin is further injected to a predetermined height or required by an optical molding device. The step of forming into a shape is repeated a predetermined number of times. This makes it possible to obtain a model type capable of measuring internal strain at a predetermined position.

Further, the method of manufacturing a model for analyzing the internal stress of a mold according to the present invention is characterized in that a portion to be integrally molded under atmospheric pressure or reduced pressure and a laminated structure portion in which a strain gauge or an optical fiber is embedded at a predetermined position in the interior. A method according to Item 6, characterized in that the integrally molded portion and the laminated structure portion are combined. As a result, only the integrally molded part having a shape corresponding to the mold to be analyzed is manufactured, and the internal strain of the model mold is measured by using the laminated structure part which is troublesome to manufacture without remanufacturing a new one. This makes it possible to obtain an effect of improving workability in manufacturing the model die and reducing costs.

In the present invention, as described above, a simulation experiment is performed in accordance with the actual process to be analyzed using a model die and a model workpiece, instead of the actual mold and workpiece, and measurement is performed by the experiment. The actual die design is optimized based on the amount of change in the internal stress or strain of the model die.

Examples of the material used as the model die and the model workpiece include a plastic material such as plasticine as the model workpiece, and an elastic material continuous body (solid material) such as a resin as the model die. Are used in combination to perform a simulation experiment within the elastic deformation range of the model type. In this way, it is possible to perform an accurate simulation experiment according to the actual process with a smaller load, as compared with the conventional method of performing the analysis by the actual process using the actual mold and the metal material. , Simple. In addition, it is easier to process the model mold than to actually fabricate the mold, because the material is cheaper.

In the model type, the amount of change in the internal strain in a simulation experiment is calculated, for example, in each direction component of a three-dimensional orthogonal coordinate system (x, y, z) or in each direction of a cylindrical coordinate system (r, θ, z). A strain gauge is embedded in a predetermined position in advance so that the component can be measured. Alternatively, the optical fiber may be buried in the same manner, and the amount of change in the internal strain may be detected by measuring the amount of change in the ratio between the amount of incident light and the amount of output light to the optical fiber in the course of the simulation experiment. Pressure sensors can be buried instead of these, but pressure sensors are generally expensive, and their size is as large as about φ6 mm. Since it has a great influence on the shape, it is difficult to accurately measure the pressure at the target measurement point, which is not preferable. On the other hand, the strain gauge or the optical fiber has a smaller shape than the pressure sensor and is easy to mount. It is generally cheaper than a pressure sensor. Using these, the amount of change in strain at each measurement point of the model type is measured, and the following equation, which is a conversion formula from strain to stress based on Hooke's law, is used.

(Equation 1) , The stress components σ _{r at} each measurement point,
Shigumashita, it is possible to calculate the sigma _z. Further, by performing linear interpolation based on the measurement points, it is possible to calculate the internal stress at an arbitrary point in the entire model type. Equation 1 is a calculation formula in the cylindrical coordinate system, but also in the rectangular coordinate system, the output values (measured values) ε _x , ε _y , ε of the strain gauges in the model type.
Similarly stress component sigma _x by _z, σ _y, can be determined sigma _z. By performing the analysis in this manner, the state in which the workpiece is sequentially contacted with the mold due to the plastic deformation can be reproduced as an actual phenomenon, and the internal stress caused by the reaction force to the mold generated there can be measured. That is, compared to the analysis by the conventional finite element method, the method is more suitable for the actual process, and does not require any complicated calculation as in the related art, and is easy.

As a method of obtaining a model type having a structure in which a strain gauge or an optical fiber is embedded at a predetermined position inside,
(1) an injection molding method, (2) a method of cutting a solid resin, and (3) a method of curing a liquid resin at room temperature can be considered. The present inventors have studied them. Hereinafter, the contents of the study will be described.

(1) Injection molding method First, although the injection molding method can process the shape of the model mold itself with high precision, the resin temperature at the time of processing exceeds the heat resistance temperature of the strain gauge or the optical sensor. It is considered to be difficult to manufacture, and the price of the device is high, which is not preferable.

(2) Method of Cutting Solid Resin On the other hand, the method of cutting solid resin is inexpensive in material. As a solid resin, in a simulation experiment using plasticine as a work material, polypropylene which is a material having a low elastic modulus capable of obtaining a sufficient strain response even under a low pressure was used. First, in this polypropylene, it is required that the amount of strain linearly changes with respect to the pressure generated by the compression processing for processing within the elastic deformation range. After confirming this,
The results were good as shown in FIG.

Then, a cylindrical model is made of polypropylene, and a strain gauge is buried inside by cutting the model to obtain a cylindrical model (r, θ, z) in each direction component. The internal strain is measured. First, as shown in FIG.
A half ring-shaped part 210 was obtained by cutting to a thickness of mm and further dividing it vertically into two parts. Then, each semi-ring shaped part 210
The strain gauges 220 were stuck at four locations at the same radial distance position with an adhesive. At this time, a perpendicular gauge was used so that the strain in the r and θ directions could be accurately measured at right angles. Also, a strain gauge 220 was similarly attached to the longitudinal section of each half-ring-shaped part 210 so that the strain in the z direction could be measured. Next, these ring-shaped parts 210 were re-assembled and low-pressure inserted into a reinforcing ring 230 of the same material so as not to be separated.

Next, as shown in FIG.
A rubber hose 310 having an outer diameter of φ30 and an inner diameter of 25 (mm) is inserted into the inner diameter of 0, and a wooden rod (not shown) is inserted in order to correct the bending of the rubber hose 310. Rubber hose 31
The internal pressure was applied to 0, and the amount of strain detected by each strain gauge 220 at this time was recorded. The internal pressure is measured by the pressure sensor 32.
It was measured at 0. In addition, the internal pressure load test was performed on the rubber hose 310 in a single state in advance, and 7 to 8 kgf / c
It was confirmed that m ² was the burst limit.

In the above strain amount measurement experiment, the strain amount increases linearly with an increase in the internal pressure of the rubber hose 310, and the strain amount generated at four measurement points on one half-ring-shaped component 210 has a theoretical tendency. Similarity is required. But,
As shown in FIG. 4, the actual measurement results showed that there were few cases in which the amount of strain changed almost linearly, and the correlation with the distance in the r direction was not clear. In some cases, a value indicating compression was measured at a measurement point where tension should have occurred theoretically, or vice versa. As the causes thereof, it is considered that dimensional changes and gaps are generated due to cutting and re-assembly, and unexpected stress states are generated due to structural torsion and the like.

Therefore, in order to remove a gap or a displacement between the half ring-shaped parts 210 in the reinforcing ring 230, z
I thought about strengthening the direction. That is, the reinforcing ring 230 made of polypropylene was made again of a metal material, and was strongly tightened in the z-direction with screws, and the same pressurization experiment was performed again. However, as a result, the tendency of the measured strain amount still varied and was not stable. Therefore, it has been found that it is difficult to accurately measure the internal stress of the model obtained by cutting the solid resin.

(3) Method of Curing Liquid Resin Next, a method of curing a liquid resin, which is inexpensive like a solid resin, was examined. More specifically, an experiment was performed using two types of two-component mixed resins having a high elastic modulus and a low elastic modulus composed of the present agent and a curing agent.

FIG. 5 shows (a) an epoxy resin having a high elastic modulus and (b) an epoxy resin having a low elastic modulus.
The commercially available products shown in the table were prepared and examined.

After weighing the present agent and the curing agent, the agent and the curing agent were put into a thin polypropylene container for mixing and stirred. Although the temperature rose after the start of stirring, it did not affect the molding container, but returned to room temperature after about 4 hours, cured, and easily released from the container. Although a slight shrinkage was observed in the center portion, no shrinkage was observed on the contact surface with the molding container. It was left as it was until the next day, and a strain gauge having a standard resistance value of 120Ω was attached in each of the r direction and the θ direction of the resin. Thereafter, the resin was put into the container again, and the present agent and the curing agent were added thereto as described above, and after the curing, the resin was released. In addition, FIG. 6 shows the results of actually measuring the resistance values of the respective strain gauges before and after application, during application of the resin, and during and after curing. In each case, there was no significant change in the resistance value, and it was found that heat generated during curing of the resin hardly affected the measurement ability of the strain gauge.

Next, a transparent rubber hose was inserted into the inner diameter portion of the mold, and a response test of a strain gauge was performed when pressure was applied from the inside. The results are shown in FIGS. FIG. 7A shows the measurement results when the high elastic modulus epoxy resin was left until the day after molding, and shows a good response except for the initial stage of pressurization. FIG. 7B shows the result when the high elasticity epoxy resin was further left for one day, and the response failure in the initial stage of pressurization was improved as compared with the previous result.
This seems to be due to the fact that even though the resin seems to be completely cured the next day after production, it has not been completely cured microscopically, and the curing has gradually progressed with the passage of time. . On the other hand, the low elastic modulus epoxy resin showed a good response as shown in FIG. In addition, the response amount is about 10 times as large as that of the high elasticity epoxy resin, and it is clear that measurement is easy even with a small strain, and it is clear that it is more desirable.

According to the above examination results, the model mold is a method of curing the liquid resin, that is, after injecting the resin to a predetermined height in the mold, once curing the resin, fixing the strain gauge at a predetermined position on the upper surface thereof, Thereafter, it has been found that a method of repeating the step of injecting the resin to a predetermined height a predetermined number of times is optimal. This makes it possible to accurately and easily fix the strain gauge or optical fiber at a predetermined position in the model mold. It is thought that the strain gauge buried in the wing responds well and contributes to accurate analysis.

The model mold must be prepared each time according to the shape of the mold to be analyzed. However, the above-described manufacturing method using liquid resin curing requires time and labor for manufacturing, and thus, manufacturing each time according to the shape of the analysis target mold has a problem in terms of cost. Therefore, if it is divided into an integral molded part having a shape similar to the mold to be analyzed and a laminated structure part in which a strain gauge is embedded at a predetermined position inside, the latter, which is troublesome to manufacture, is common to all molds. Can be economical.

Alternatively, a wedge-shaped cassette part in which a strain gauge or an optical fiber is buried in a predetermined position in advance, and a strain gauge or an optical fiber is mechanically continuous by a wedge effect in a state where the cassette part is fitted, and is located in all predetermined positions inside. If the structure is divided into a main body having a structure that can be fixed, the former which is troublesome in manufacturing can be made common to all the dies, which is also economical.

[0034]

(Embodiment 1) An example of an embodiment of a method for analyzing internal stress of a mold according to the present invention will be described. The mold internal stress analysis process according to the present invention is performed by the following steps. Design the working process of plastic working. Design a mold for each processing process. In the above, a model mold in which a strain gauge or an optical fiber is buried at a predetermined internal position is produced by a continuous body of elastic material such as resin (solid material) with respect to a mold whose internal stress is to be analyzed. As a material to be processed, plasticine or the like, which is a model material similar to the characteristic deformation of a metal material, is prepared. Using the model and the model material, a simulation experiment is performed within the elastic deformation range of the model according to the actual process of machining. Measure the amount of change in the internal strain or internal stress of the model type at an elapse point or a continuous point arbitrarily selected from all the processes, and analyze the measurement result at each measurement point.If a desired result is not obtained, process. Change the conditions and return to. If the desired result is not obtained, change the mold shape and return to.

As described above, it is possible to obtain measurement data including the influence of the shape of the workpiece and the distribution of friction, which change every moment in the plastic working process, and perform analysis in accordance with the actual process as compared with the related art. High reliability can be expected. Further, the production of the model mold is much easier and at a lower cost than the production of the actual mold, and it is possible to easily carry out a simulation experiment in which each examination item in the processing process design is widely changed.

Next, FIG. 8 shows an example of the device configuration in the above simulation experiment. (A) Press machine 801 including a press 801, a press sensor unit 802 such as a load meter and a displacement meter, a punch 803, a model 804 having a strain gauge embedded therein, and a bolster 805, and (b) a press sensor unit (C) a recorder 8 having a CPU capable of storing and processing the amplified voltage.
20, (d) a bridge box 830 connected to a strain gauge terminal, and (e) an information processing device 840 into which an analysis program for analyzing internal stress from a strain-equivalent voltage detected by the strain gauge is incorporated. Become. Note that the constituent material of the punch 803 is determined according to the mechanical characteristics of the model die and the material forming the model material, and is made of, for example, the same resin as the model die.

(Embodiment 2) An example of an embodiment of a method of manufacturing a model die for internal stress analysis of a die according to the present invention will be described. The epoxy resin main agent and the curing agent shown in FIG. 5 are placed in, for example, a thin polypropylene container and stirred. Next, it is poured into a molding frame 900 of FIG. Mold form 90
0 is produced according to the dimensions of the model model to be analyzed, and is provided by an L-shaped jig 910, a convex jig 920, and a 3/4 ring-shaped jig 930 for accurately embedding the strain gauge at a predetermined position. Become. For these, a release agent such as silicon is applied to the inner surface in advance. Convex jig 920 and L-shaped jig 9
10 has a structure combined with the notch of the convex jig 920, and 3/4
The ring-shaped jigs 930 are placed one on top of the other, and the liquid resin flows into the ring-shaped jigs 930 sequentially, so that the resins can be stacked at a constant height.

First, the first-stage 3/4 ring type jig 930 is placed, and after the liquid resin has flowed in and completely cured, FIG.
As shown in (a), a strain gauge 220 is attached to a predetermined position (r direction, θ direction) on the upper surface of the resin. The strain gauge 220 is
Although a uniaxial gauge may be used, if a gauge equipped with a plurality of measuring elements, for example, a five-element special strain gauge 1000 shown in FIG. 10B is used, the distance between a plurality of measuring points,
This is more preferable because it can eliminate variations in the inclination with respect to the center axis and reduce the time and effort for sticking. The strain gauge is applied with an instant adhesive.

Next, the second stage 3/4 ring type jig 93
After setting 0, the liquid resin flows again, and after curing, a strain gauge is attached. This operation is repeated, and finally, the liquid resin is poured in a state where all the 3/4 ring-type jigs are stacked. When the whole is hardened, it is once taken out of the molding frame, and a gauge for measuring the strain in the z-direction is affixed to the portion that has been in contact with the L-shaped jig 910. Note that, in order to facilitate the attachment of the strain gauge at this time, for example, a minute projection 911 or the like may be provided in advance on the side surface of the L-shaped jig 910 as a marker indicating the position where the strain gauge is attached. When the application of the strain gauge is completed, FIG.
Is returned into another molding frame 1100, and the internal liquid resin flows therein, is cured, and is released, thereby obtaining a model mold.

The inner shapes of the molding containers 900 and 1100 are tapered in advance so that they can be released later, and machined again to make the outer peripheral portion of the molded model die perpendicular to the end face. May be performed.

(Embodiment 3) Another embodiment of the method of manufacturing a model die for internal stress analysis according to the present invention will be described.
In the present embodiment, as shown in FIG.
And a model type 1200 divided into a core section 1220 and a core section 1220. The inner part 1210 is integrally molded by flowing a liquid resin into a molding die formed according to the shape of the model model to be analyzed. The core portion 1220 is a laminated structure in which a strain gauge is embedded, and is manufactured by the same procedure as in the first embodiment. The inner part 12
It is desirable that the fitting portion be provided with a taper so that the 10 and the core portion 1220 function as an integral structure when they are combined. In this case, a wedge effect occurs naturally between the two due to the stress load in the simulation experiment, and an operation as an integral structure is obtained.

(Embodiment 4) Still another embodiment of the method for manufacturing a model die for internal stress analysis of a die according to the present invention will be described. In the present embodiment, as shown in FIG.
0 and a model type divided into a cassette unit 1320. The main body 1310 is integrally formed by flowing a liquid resin into a molding die formed in accordance with the shape of the model model to be analyzed, or is formed by an optical molding device. The cassette section 1320 is a laminated structure section in which a strain gauge is embedded, and is manufactured by the same procedure as in the first embodiment. Also in the model type having such a structure, similarly to the third embodiment, it is required that a wedge effect occurs between the two at the time of an experiment to form an integrated structure. Therefore, the main body 1
A simulation experiment is performed in a state where a taper is provided in a fitting portion between the cassette 310 and the cassette unit 1320 and a hydrostatic pressure is externally applied. In this case, since the data of the measured strain amount includes the influence of the hydrostatic pressure, the data of the desired strain amount is obtained by removing the data. In such a case, the information processing device 8 described in the first embodiment
The analysis program in 40 may be such a program that, for example, if a value is previously input when a hydrostatic pressure is applied, the value is automatically removed from the measurement data and analysis is performed.

[0043]

Embodiments of the present invention will be described below. First, a cylindrical model having an outer diameter of 88 mm and an inner diameter of 31 mm was manufactured using the low elastic modulus epoxy resin shown in FIG. The strain gauge measures the resistance value in advance and confirms that there is no abnormal connection.
An element special strain gauge was used. As for the measurement points where the strain gauges are installed, four points are provided on each of the seven layers in each of the r direction, the θ direction, and the z direction.

After the resin in which the strain gauge is embedded is completely cured, the resin is released from the mold and the bottom end face is flattened by cutting. Connect the terminals of each strain gauge to the bridge box. Switching of the connection between the strain gauge terminal and the bridge box is performed one by one using a lighting connector so that measurement can be performed for each layer.

First, the characteristics of this model type are examined. Insert a commercially available rubber hose into the inner shape of the model type and apply internal pressure. Responsiveness of measured strain value to pressure when pressure is applied to about 3 kg / cm ² Relation of magnitude of strain between measuring points at different radial distances Absolute value of strain at measuring points at the same radial distance between layers The comparison of was confirmed. The results are shown in FIG. 14. The results of and are good, but a slight difference was observed in the absolute value of the strain amount between the respective layers. However, since the response of the measured strain amount is sufficiently good, a simulation experiment was actually performed using this model type. Each condition of the experiment is shown below. Model material: 28.9 x 44 mm plasticine Lubricant: Vaseline Measuring device: Recorder (14 input units) 1 Bridge box 12 Strain amplifier (strain amplifier) 13 Load cell (for 1 ton) 1 Displacement gauge 1 Displacement amplifier 1 unit Processing temperature: room temperature (23 ° C) Processing speed: 35 mm / sec Compression stroke: about 20 mm

The amount of strain, displacement, and processing load at each of the four points in the r, θ, and z directions were simultaneously recorded for each layer. The result is shown in FIG. In all the layers, a state of occurrence of a complicated strain without regularity is recorded, and a state in which the direction of the strain changes from tension in the initial stage of processing to compression is recorded. Such a complicated strain behavior is difficult to predict by the conventional finite element method, and can be analyzed only by data based on actual measurement as shown here. Also, here we are measuring continuously,
The measurement may be performed only for the set lapse point as needed, and in this case, the measurement is more simplified.

[0047]

As described above, according to the present invention, it is possible to simply, efficiently and accurately analyze the internal stress distribution of a mold in each step of metal plastic working.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in the amount of strain of polypropylene with respect to a compressive load.

FIG. 2 is a schematic diagram for explaining a method of attaching a model mold and a strain gauge prepared by cutting solid resin.

FIG. 3 is a schematic view showing a method for measuring a strain amount of a model of a solid resin model under an internal pressure load.

FIG. 4 is a view showing a measurement result of a strain amount of a solid resin model type due to an internal pressure load.

FIG. 5 is a table showing the types and characteristics of two-pack mixed-resin model dies comprising a main agent and a curing agent to be examined as model type constituent materials.

FIG. 6 is a table showing measurement results of resistance values of strain gauges before and after resin curing.

FIG. 7 is a diagram showing a measurement result of a strain amount of a model type made of a two-part mixed resin made of the present agent and a curing agent under an internal pressure load.

FIG. 8 is a schematic diagram of a configuration of a simulation experiment apparatus in the analysis method of the present invention.

FIG. 9 is an explanatory diagram of a molding frame used for producing a model mold using a two-component mixed type resin composed of the present agent and a curing agent.

FIG. 10 is an explanatory diagram of a position where a strain gauge is attached.

FIG. 11 is a schematic view of a molding form.

FIG. 12 is an example of a model type structure.

FIG. 13 is another example of a model type structure.

FIG. 14 is a diagram illustrating a result of inspecting characteristics of a model type.

FIG. 15 is a diagram showing the results of a simulation experiment using a model type.

[Explanation of symbols]

 200 Model type 210 Semi-ring part 220 Strain gauge 230 Reinforcement ring 310 Rubber hose 320 Pressure sensor 800 Press machine 801 Press 802 Press sensor unit 803 Punch 804 Model type 805 Bolster 810 Strain amplifier 820 Recorder 830 Bridge box 840 Information processing device 900, 1100 Molding frame 910 L-shaped jig 911 Small convex part 920 Convex type jig 930 3/4 ring type jig 1000 Five-element special strain gauge 1200 Model type 1210 Inner part 1220 Core part 1310 Body part 1320 Cassette part

Continued on the front page (72) Inventor Yuji Murye 1137-72 Kawauchi, Kokubu-shi, Kagoshima F-term in Kagoshima Brain Center (reference) 2F063 AA25 BA30 DA05 DD06 EC22 4E050 JB10 5B049 BB07 EE41

Claims (7)

[Claims] An elastic deformation of a model type using a model type made of an elastic material continuous body (solid material) such as a resin and using a model material similar to a deformation characteristic of a metal material as a material to be processed. Within the range, a simulation experiment was performed in accordance with the actual process of plastic working with the model material, and the change amount of the internal strain or internal stress of the model type was measured at an elapse point or a continuous point arbitrarily selected from all the processes. And analyzing the measurement result at each measurement point. 2. An element capable of detecting strain or stress, such as a strain gauge or an optical fiber, is buried at a predetermined position inside the model type, and the amount of change in the internal strain is measured and analyzed. 3. The method for analyzing the internal stress of a mold according to the above. 3. The shape of the mold to be analyzed is such that the model mold is in close contact with the core part and is mechanically continuous with a laminated core part in which a strain gauge or an optical fiber is embedded at a predetermined position inside. 3. The method according to claim 2, comprising a wedge-shaped inner part produced in accordance with the method. 4. The model type is dynamically connected to a wedge-shaped cassette section in which a strain gauge or an optical fiber is buried in a predetermined position in advance by a wedge effect when the cassette section is fitted, and all of the internal parts are connected. A main unit having a structure capable of fixing a strain gauge or an optical fiber at a predetermined position, and the cassette unit is fitted to the main unit, and the strain is applied in a state where hydrostatic pressure is applied from the outside of the entire model mold. 3. The method according to claim 2, wherein the amount of change in the internal strain is measured and analyzed using a gauge or an optical fiber. 5. Atmospheric pressure or reduced pressure, a two-pack resin composed of the present agent and a curing agent is injected into a mold in which a strain gauge or an optical fiber is fixed at a predetermined position in advance, and the resin is cured. A method for manufacturing a model die for analyzing internal stress of a die, characterized by comprising: 6. Atmospheric pressure or reduced pressure, a two-pack mixed resin composed of the present agent and a curing agent is injected to a predetermined height in a mold frame, and then hardened once or by using an optical shaping device. It is shaped into a shape, a strain gauge or an optical fiber is fixed at a predetermined position on the upper surface thereof, and then the process of injecting the resin to a predetermined height or shaping to a required shape with an optical shaping device is repeated a predetermined number of times. Model manufacturing method for internal stress analysis of die. 7. A method according to claim 6, wherein a part to be integrally formed under atmospheric pressure or reduced pressure and a laminated structure part in which a strain gauge or an optical fiber is embedded at a predetermined position in the inside are manufactured by the method according to claim 6, respectively. A method for manufacturing a model die for internal stress analysis of a mold, comprising combining a part and a laminated structure part.