JP2015013312A - Hot forging process evaluation system, and product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of measuring the temperature of a mold surface highly accurately taking mold wear into consideration in evaluation of a hot forging process.SOLUTION: A hot forging process evaluation system has: a plurality of thermocouples 26 joined to a mold 4 at different depths from the surface of the mold 4;a relational expression 14 between a ratio of temperature raising rate and a wear amount showing a relationship between a ratio of temperature raising rate among the plurality of thermocouples 26 and a wear amount of the mold 4 with respect to the ratio of temperature raising rate; and a calculation section 16 which calculates the wear amount of the mold 4 by the ratio of temperature raising rate among the plurality of thermocouples 26 based on temperature history by the plurality of thermocouples 26 by using the relational expression 14 between a ratio of temperature raising rate and a wear amount, calculates the temperature of the surface of the mold 4 by inverse analysis after correcting the depths of the plurality of thermocouples 26 by the calculated wear amount, and evaluates process of hot forging by the calculated temperature of the surface of the mold 4.

Description

  The present invention is intended for hot press working technology in which a metal material is heated to a high temperature at which deformation resistance is sufficiently low to perform plastic working, particularly hot forging technology. The present invention relates to an evaluation system for evaluating whether or not a pressing process is properly performed, and a product manufactured by evaluation using the evaluation system.

  In processing a metal material, a processing method in which a material is plastically deformed is generally called press processing or plastic processing. In press working, a method of working at a temperature of 800 ° C. or higher is called hot working if the work is particularly high temperature, for example, iron-based material. The press working can be roughly divided into two types, one for processing a plate material and one for processing a bulk material, and the latter is called forging. Forging requires a large forming load in order to apply a large deformation to a metal. In addition, since the amount of strain is large, problems such as cracks are likely to occur in cold working performed at room temperature. Therefore, forging of large products is often performed hot.

  For hot forging, the temperature of the mold is heated to about 200 to 300 ° C., the material temperature is heated to about 800 to 1200 ° C. and forging is performed, and the mold is placed in a furnace together with the material. There is a constant temperature forging that heats to the same temperature. Constant temperature forging is generally applied to special processing that requires a long processing time such as superplastic forming. The present invention is intended for normal hot forging in which the mold temperature is maintained at about 200 to 300 ° C.

  The purpose of hot forging is not only to reduce the molding load. The metal material is originally made by casting, but the cast material has a shrinkage cavity inside, or the crystal grains are coarse, so that the material as it is has insufficient strength reliability. An internal shrinkage cavity can be eliminated by heat-treating this with a large deformation by hot forging. Further, when a large strain is applied to the crystal grains and the heat treatment is performed, the crystal grains become finer. This is called crystal grain refinement by recrystallization. A small crystal grain size prevents the growth of cracks and leads to improved toughness of the material.

  Refinement by recrystallization is carried out by generating new grain boundaries so as to absorb the transition by using the elastic energy of the transition introduced in large quantities in the crystal as a result of large deformation. The state where the grain boundary also has energy and the crystal grain size is small is a metastable state in terms of energy, and the crystal grain size gradually grows when held at a high temperature. Strain introduced by forging, strain rate, and temperature affect the grain size after recrystallization. Therefore, in order to obtain a material having a desired crystal grain size, it is important to strictly control the temperature together with the strain amount and strain rate applied in the forging process.

  In particular, a Ni-based heat-resistant alloy used for a turbine disk of a jet engine is required to have a material structure having an average particle size of about 10 μm in order to withstand low cycle fatigue. 10 μm is a crystal grain size that is about one-tenth of that of a generally distributed metal material and is extremely small. Moreover, since it is in an unstable state with high grain boundary energy, crystal grains easily grow when the material temperature exceeds an appropriate temperature. Therefore, control of the material temperature in the width | variety about 10 degreeC is calculated | required.

  In the hot forging of a turbine disk, the material is heated to around 1000 ° C. in a precisely temperature-controlled furnace, transported onto a mold and forged. However, due to the high temperature, the material temperature changes every moment, Originally, it is desirable to measure the material temperature in the mold. In particular, it is necessary to perform temperature measurement in the mold in order to perform measurement consistently throughout the forging time.

  For example, there are Patent Documents 1 to 3 as prior art documents. Patent Document 1 shows a method for measuring a material temperature used in hot working of a thin metal plate called a hot stamp. In this technique, the location where the thermocouple is attached in contact with the material is an ultrathin plate, thereby reducing the heat capacity and improving the followability of the thermocouple measurement temperature to the material temperature.

  Further, Patent Document 2 shows that the film thickness of the coating film on the mold surface is measured based on the difference value of the measured temperature distribution calculated from the intensity distribution of two types of infrared rays having different wavelengths, and based on that. This is a surface temperature inspection device that corrects the emissivity distribution and accurately measures the surface temperature of the mold.

  Patent Document 3 uses a temperature measurement method that calculates the temperature of the working surface of a mold by performing an unsteady electrothermal inverse problem analysis using temperature data of two points embedded in a mold or a mold. Is. Using it, the galling of the operating surface is judged from the temperature of the operating surface. Alternatively, it is a method of determining that seizure has occurred when the difference between the freezing point of the forged product and the temperature of the mold surface is smaller than a certain value (temperature decrease amount due to the electric heating resistance of the lubricant).

JP 2011-83812 A JP 2008-215957 A Japanese Patent Laid-Open No. 2007-167871

  By the way, as a result of the study by the present inventor regarding the prior art including the Patent Documents 1 to 3, the following has been clarified.

  The method disclosed in Patent Document 1 is a method suitable for processing a plate material in which the pressure applied to the mold is relatively small. However, in forging, a pressure exceeding the yield stress of the material is applied to the mold, The temperature measuring device formed in the above cannot be damaged.

  In the method disclosed in Patent Document 2, the temperature of the mold surface in the absence of material can be measured, but the temperature of the mold surface during processing cannot be measured.

  Further, according to the method disclosed in Patent Document 3, it is possible to measure the temperature of the die surface during forging. For example, the time during which the mold and the material are in contact with each other during hot forging is as short as about 0.1 seconds to about 10 seconds, and the heat flow in the mold is unsteady. In general, in order to handle the phenomenon of unsteady heat conduction by inverse analysis, such as measurement of mold temperature during hot forging, temperature distribution as an initial condition and temperature history as a boundary condition are required. The condition coordinates need to be known.

  However, a hot forging die is generally processed several thousand to several tens of thousands of times with one die, and the die surface is worn in the process. If the thermocouple depth changes due to wear of the mold, if the depth is obtained and the inverse analysis of the mold surface temperature is not performed using the post-wear thermocouple depth, the mold surface temperature is accurately determined by reverse analysis. Cannot be calculated.

  Therefore, there is a need for a method for measuring the temperature of the mold surface with higher accuracy by measuring the change in the thermocouple depth due to mold wear and changing the thermocouple depth under the input conditions of inverse analysis. .

  In addition, the measurement of the crystal grain size by observing the microstructure is expensive to apply to production management, and there is also a need for a technique for screening work with a high risk of crystal grain growth by high-precision temperature measurement. Yes.

  Therefore, the present invention solves the above-described problems, and a typical object thereof is to provide a technique for measuring the temperature of the mold surface with high accuracy in consideration of mold wear in the evaluation of the hot forging process. There is to do.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  That is, a typical hot forging process evaluation system calculates the temperature of the mold surface by inverse analysis using the temperature history by the temperature measuring device, and performs hot forging at the calculated temperature of the mold surface. A system for evaluating processes. The system includes a plurality of temperature measuring devices bonded to the mold at different depths from the surface of the mold, a temperature rising rate ratio between the plurality of temperature measuring devices, and the temperature rising rate ratio. Based on temperature history by the plurality of temperature measuring devices using the temperature rise rate ratio / wear amount relation information indicating the relationship between the mold wear amount and the temperature rise rate ratio / wear amount relation information. The amount of wear of the mold is calculated from the heating rate ratio between the plurality of temperature measuring devices, and the mold is subjected to inverse analysis after correcting the depth of the plurality of temperature measuring devices with the calculated amount of wear. And a calculation unit that evaluates the hot forging process at the calculated surface temperature of the mold.

  Further, the present invention is also applied to a product manufactured by being evaluated by the hot forging process evaluation system.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  That is, a typical effect is that the temperature of the mold surface can be measured with high accuracy in consideration of mold wear in the evaluation of the hot forging process.

It is a figure which shows an example of schematic structure of the hot forging process evaluation system in one embodiment of this invention. In the hot forging process evaluation system of FIG. 1, it is an enlarged view which shows an example of the location where the upper mold | type thermocouple unit is mounted | worn. FIG. 2 is a perspective view showing an example of a thermocouple unit in the hot forging process evaluation system of FIG. 1. In the hot forging process evaluation system of FIG. 1, it is sectional drawing explaining an example of the abrasion loss of a thermocouple unit. It is a figure explaining an example of the conditions of a finite element method analysis in the simulation in one embodiment of the present invention. It is a figure which displays an example of an analysis result on the conditions of FIG. It is a figure which shows an example of the result of having carried out the reverse analysis of the metal mold | die surface temperature, without considering the amount of wear on the conditions of FIG. In the result of FIG. 6, it is a figure which shows an example of the temperature history of the first 0.1 second. In the result of FIG. 8, it is a figure explaining an example of the relationship between wear amount and a temperature increase rate ratio. It is a figure explaining an example of the relational expression used for a metal mold | die wear amount evaluation algorithm with the result of FIG. FIG. 6 is a diagram illustrating an example of a reverse analysis result of a mold surface temperature when the distance is corrected in consideration of the wear amount and the distance is not corrected without considering the wear amount under the conditions of FIG. 5. In the hot forging process evaluation system of FIG. 1, it is a figure which shows an example of the temperature history display screen displayed on a display part. It is a figure which shows an example of the heat flow display screen which changes from the temperature history display screen of FIG. It is a figure which shows an example of the temperature increase rate ratio display screen displayed on the graph display part of FIG. In the hot forging process evaluation system of FIG. 1, it is a figure which shows an example of a comparison display screen with the past performance data displayed on a display part. It is a figure which shows an example of the hot forging goods manufactured by evaluating with the hot forging process evaluation system of FIG.

  In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant and one is the other. There are some or all of the modifications, details, supplementary explanations, and the like. Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

[Outline of the embodiment]
First, an outline of the embodiment will be described. In the outline of the present embodiment, as an example, the reference numerals of the corresponding components of the embodiment are given in parentheses.

  The representative hot forging process evaluation system of the present embodiment calculates the surface temperature of a mold (mold 4 (lower mold 2, upper mold 3)) by inverse analysis using a temperature history by a temperature measuring instrument. In this system, the hot forging process is evaluated based on the calculated temperature of the mold surface. The system includes a plurality of temperature measuring devices (thermocouple 26 (thermocouple A28, thermocouple B29)) joined to the die at different depths from the surface of the die, and a plurality of temperature measuring devices. Temperature rise rate ratio / wear amount relation information (temperature rise rate ratio / wear amount relational expression 14) showing the relationship between the temperature rise rate ratio between each other and the wear amount of the mold with respect to the temperature rise rate ratio; Using the temperature rise rate ratio / wear amount relation information, the wear amount of the mold is calculated from the temperature rise rate ratio between the plurality of temperature measuring devices based on the temperature history by the plurality of temperature measuring devices. Then, after correcting the depths of the plurality of temperature measuring devices with the calculated wear amount, the surface temperature of the mold is calculated by inverse analysis, and the hot forging process is performed at the calculated surface temperature of the mold. And a calculation unit (calculation unit 16).

  Hereinafter, an embodiment based on the outline of the above-described embodiment will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

[One Embodiment]
A hot forging process evaluation system in the present embodiment and a product manufactured by evaluation using the hot forging process evaluation system will be described with reference to FIGS. In the present embodiment, for example, a hot forging process of a turbine disk of a jet engine will be described as an example, but the present invention is not limited to this.

<Configuration and operation of hot forging process evaluation system>
First, the configuration and operation of the hot forging process evaluation system in the present embodiment will be described with reference to FIG. FIG. 1 is a diagram showing an example of a schematic configuration of this hot forging process evaluation system.

  The hot forging process evaluation system in the present embodiment includes a mold 4 composed of a lower mold 2 and an upper mold 3 for processing a material 1, a thermocouple unit 5 for measuring the temperature of the mold 4, and a thermocouple unit. 5 includes a receiver 6 that receives a signal from 5, a thermocouple signal processing device 7 that receives and processes the signal from the receiver 6, and an operation unit 18 that is connected to the thermocouple signal processing device 7. .

  The material 1 is processed by a lower die 2 attached to a bolster (not shown) of a press (not shown) and an upper die 3 attached to a slide (not shown). The lower mold 2 and the upper mold 3 are collectively referred to as a mold 4. A plurality of thermocouple units 5, which are temperature measuring instruments for measuring the temperature of the mold 4, are incorporated on the surface of the mold 4 that contacts the material 1. FIG. 1 shows an example in which three thermocouple units 5 are incorporated in the lower die 2 and three thermocouple units 5 are incorporated in the upper die 3, respectively. Each thermocouple unit 5 is composed of two thermocouples 26. Yes. Although details will be described later, the thermocouple unit 5 is joined to the thermocouple unit 5 at two different depths from the surface of the mold 4. The temperature measuring device for measuring the temperature of the mold 4 is not limited to a thermocouple, and any device that can measure the temperature may be used.

  The receiver 6 is connected to the thermocouple unit 5 incorporated in the mold 4 on the input side, and connected to the thermocouple signal processing device 7 on the output side. The receiver 6 receives a voltage signal emitted from the thermocouple unit 5, converts this voltage into a temperature, and transmits data of this temperature to the thermocouple signal processing device 7.

  The thermocouple signal processing device 7 includes a thermocouple temperature history database 9, a mold surface temperature history database 11, a mold surface temperature calculation algorithm 12, a mold wear amount evaluation algorithm 13, a temperature increase rate ratio / wear amount relational expression 14, The hot forging process pass / fail judgment criteria 15, thermocouple depth data 17 and the like are stored. In addition, the thermocouple signal processing device 7 includes a calculation unit 16 that executes various calculation processes using the stored data, algorithms, and the like.

  The thermocouple temperature history database 9 is a database that stores temperature data received from the receiver 6 as thermocouple temperature history data 8. The mold surface temperature history database 11 is a database for storing the mold surface temperature history data 10. The mold surface temperature calculation algorithm 12 is an algorithm for calculating the surface temperature of the mold 4. The mold wear amount evaluation algorithm 13 is an algorithm for evaluating the wear amount of the mold 4.

  The temperature increase rate ratio / wear amount relational expression 14 is an expression showing the relationship between the temperature increase rate ratio between the thermocouples and the wear amount of the mold 4. The information indicating the relationship between the temperature increase rate ratio and the wear amount is not limited to a formula but may be a table. The hot forging process quality determination criterion 15 is data serving as a criterion for determining the quality of the hot forging process. The thermocouple depth data 17 is data indicating the depth of the thermocouple from the surface of the mold 4.

  The operation unit 18 includes a display unit 19, a keyboard 20, a mouse 21, and the like. The operation unit 18 is connected to the thermocouple signal processing device 7, and the user communicates with the thermocouple signal processing device 7 by operating the keyboard 20 and the mouse 21, and the mold surface temperature history data 10 and the thermoelectrics are displayed on the display unit 19. It is possible to display temperature history data 8, thermocouple depth data 17, and the like. The display unit 19 can also display a result of statistical processing of a plurality of mold surface temperature history data 10 in the mold surface temperature history database 11.

  The operation in this hot forging process evaluation system is as follows. In the course of the hot forging process, a voltage signal for measuring the surface temperature of the mold 4 is generated from the thermocouple unit 5 in which the thermocouple is joined at two different depths from the surface of the mold 4. . The voltage signal emitted from the thermocouple unit 5 is sent to the receiver 6, and the receiver 6 converts the voltage into a temperature. The temperature data is sent to the thermocouple signal processing device 7.

  The thermocouple signal processing device 7 stores the temperature data received from the receiver 6 in the thermocouple temperature history database 9 as thermocouple temperature history data 8. In addition, the thermocouple signal processing device 7 has a die surface temperature calculation algorithm 12, a die wear amount evaluation algorithm 13, a temperature increase rate ratio / wear amount relational expression 14, and a hot forging process pass / fail judgment criterion 15 in advance. Saved. Further, the initial value of the thermocouple depth data 17 is also stored in advance. The initial value of the thermocouple depth data 17 is data indicating the depth of the thermocouple from the surface of the mold 4 before the mold 4 is worn.

  In the thermocouple signal processing device 7, the thermocouple temperature history data 8 stored in the thermocouple temperature history database 9 is used in the calculation unit 16 according to the mold surface temperature calculation algorithm 12 using the initial value of the thermocouple depth data 17. Is processed, and the mold surface temperature history data 10 is calculated. The calculated mold surface temperature history data 10 is stored in the mold surface temperature history database 11.

  Further, the calculation unit 16 obtains the wear amount of the mold 4 according to the mold wear amount evaluation algorithm 13 using the thermocouple temperature history data 8 and the temperature increase rate ratio / wear amount relational expression 14, and the mold 4 The thermocouple depth data 17 is changed according to the amount of wear.

  Using this changed thermocouple depth data 17, die surface temperature history data 10 is calculated in consideration of the wear amount of the die 4. That is, the surface temperature of the mold 4 is calculated by inverse analysis using the thermocouple depth data 17 after the mold 4 is worn. The mold surface temperature history data 10 in consideration of the calculated wear amount of the mold 4 is stored in the mold surface temperature history database 11.

  Then, the calculation unit 16 uses the mold surface temperature history data 10 in consideration of the wear amount of the mold 4 and stored in the mold surface temperature history database 11 according to the hot forging process pass / fail judgment criterion 15. Judge the quality of the forging process.

  With the above processing, the wear amount of the mold 4 is calculated from the temperature increase rate ratio among a plurality of thermocouples based on the temperature history by the thermocouple unit 5 using the temperature increase rate ratio / wear amount relational expression 14. Then, after correcting the depth of the plurality of thermocouples with the calculated wear amount, the surface temperature of the mold 4 is calculated by inverse analysis, and the hot forging process is performed at the calculated surface temperature of the mold 4. Can be evaluated.

  Furthermore, when the evaluation of the hot forging process is applied to the production management of the hot forging, the number of inspections of the hot forged product after manufacture can be changed using the evaluation result. For example, it is possible to construct a production system in which the number of times used for quality inspection is increased when the deviation from the average is large, and the number used for inspection is reduced for lots close to the average.

<Structure of thermocouple unit>
The structure of the thermocouple unit 5 described above will be described with reference to FIGS.

  FIG. 2 is an enlarged view showing an example of a portion where the thermocouple unit 5 of the upper mold 3 is mounted (the circled portion in the upper drawing is shown enlarged in the lower drawing). In addition, although not shown in figure, the enlarged view of the location where the thermocouple unit 5 of the lower mold 2 is mounted is the same except that the top and bottom are reversed.

  In FIG. 2, the upper die 3 is processed with a thermocouple unit mounting portion 22, a thermocouple introduction portion 23, and a relief processing portion 24. The thermocouple unit mounting portion 22 is a portion where the thermocouple unit 5 is mounted, and is formed by removing the same shape as the thermocouple head 25. The thermocouple introduction part 23 is a part for introducing the thermocouple 26 and has a diameter smaller than that of the thermocouple unit mounting part 22. This is to form a surface that receives pressure applied to the thermocouple head 25 by forging. Moreover, since it is difficult to dig a deep hole with a small diameter, the relief processing part 24 performs a large-diameter hole.

  FIG. 3 is a perspective view showing an example of the thermocouple unit 5. The thermocouple unit 5 includes a thermocouple head 25 and two sets of thermocouples 26 (thermocouple A28 and thermocouple B29). The thermocouple head 25 has a cylindrical shape, and two sets of thermocouples 26 are joined to a groove formed at the center thereof. The material of the thermocouple head 25 is the same material as the upper mold 3 and the lower mold 2. This is to make the state of heat conduction from the surface of the thermocouple head 25 to the thermocouple unit 5 the same as the upper mold 3 and the lower mold 2.

  The thermocouple 26 (thermocouple A28, thermocouple B29) is originally composed of two lines made of different materials, but in FIG. 3, one set of thermocouples is simply represented by one line. The thermocouple 26 is joined to the thermocouple head 25 at the joint. As this joining method, a method with few melted parts due to heat, such as resistance welding or ultrasonic joining, is desirable.

  In FIG. 3, the lower surface of the thermocouple head 25 is flush with the lower surface of the upper mold 3 shown in FIG. The distances from the surface of the thermocouple head 25 to the welded portion 27, which is a joint portion with the thermocouple 26, are distance A and distance B. The distance A and the distance B are recorded in the thermocouple depth data 17 of FIG. Here, the thermocouple 26 at a distance A is a thermocouple A28, and the thermocouple 26 at a distance B is a thermocouple B29. In order to perform reverse analysis of the thermocouple depth data, the distance A and the distance B are different numbers, and the distance B is twice the distance A in a state where the distance is not worn. Here, the distance B is twice the distance A, but the inverse analysis is possible even if it is not twice. Further, if the distance A and the distance B are increased, the accuracy of the inverse analysis is lowered, and therefore a distance of about 0.1 to 10 mm is desirable.

  The thermocouple 26 (thermocouple A 28, thermocouple B 29) extends outside the mold 4 through the thermocouple introduction part 23 and the escape processing part 24, and is connected to the receiver 6. An inexpensive compensation conductor may be used between the receiver 6 and the thermocouple 26. The voltage is converted into temperature by the receiver 6 and converted as thermocouple temperature history data 8.

  The surface temperature of the mold 4 is calculated from the thermocouple temperature history data 8 of the two thermocouples of the distance A and the distance B using the mold surface temperature calculation algorithm 12. An example of the mold surface temperature calculation algorithm 12 is shown in Equation (1).

  For the calculation of the surface temperature of the mold 4, a so-called Shoji formula that solves the inverse problem of the one-dimensional unsteady heat conduction shown in the formula (1) is used. According to Shoji's equation, the surface temperature is calculated using not only the temperature data of the thermocouple at the same time but also the temperature data at the previous and subsequent times.

Therefore, after the signal generated by the thermocouple 26 that is analog continuous data is converted into temperature by the receiver 6, it is discretized every Δt and recorded in the thermocouple temperature history data 8. For example, it is increment data every 1 millisecond. In Equation (1), Ts (i) indicates the temperature at i increments on the surface of the thermocouple head 25. S (i) indicates the temperature in i increments of the thermocouple A28 at the distance A. S (i + 1) and S (i−1) are the temperatures of the thermocouple A28 at the distance A after and before Δt, respectively. T (i) is the temperature of the thermocouple B29 at the distance B. Similarly to the thermocouple A28 at the distance A, T (i + 1) and T (i-1) are temperatures after 1 increment and before the increment of the thermocouple B29 at the distance B. The coefficients from K ₁ to K ₆ can be calculated by the equations (2) to (7).

Here, x ₁ is the same value as the distance A, and x ₂ is the same value as the distance B. κ is the temperature conductivity, α ₁ and α ₂ are calculated using α _n in equation (8), and β ₁ and β ₂ are calculated using β _n in equation (9). _Br is the Bernoulli number.

<The amount of wear of the thermocouple unit and the results of examination considering this>
The amount of wear of the above-described thermocouple unit 5 and the examination results considering this will be described with reference to FIGS.

  FIG. 4 is a cross-sectional view for explaining an example of the wear amount of the thermocouple unit 5. In FIG. 4, the thermocouple unit shown in the left figure is before the wear, and the thermocouple unit shown in the right figure is worn after the wear amount 30. Due to the wear amount 30, the distance A and the distance B between the thermocouple A28 and the thermocouple B29 change to a distance A 'and a distance B', respectively.

Since the values of the distance A and the distance B are used to calculate the coefficients K _{1 to} K ₆ of the above-described equation (1), the thermocouple depth data 17 is obtained when the distance A and the distance B change due to wear of the mold 4. In order to calculate the surface temperature of the mold 4 accurately, it is necessary to recalculate the coefficients K _{1 to} K ₆ according to the actual condition.

  However, it is difficult to measure the distance A and the distance B of the thermocouple again with the thermocouple unit 5 mounted on the mold 4. In addition, since the temperature variation of the material also affects the temperature history of the thermocouple, it is theoretically impossible to calculate the thermocouple depth from the temperature history of one thermocouple.

  Therefore, the present inventors have used a finite element method simulating hot forging with NCF718, which is a typical heat-resistant Ni-based alloy, and SKD61 (both are JIS standard names), which is a typical hot forging die material. A heat conduction analysis was performed, a temperature history at a depth different from the mold surface temperature history was obtained, and a detailed study was made as to whether or not there is a feature quantity that can find a change in the amount of wear 30. A simulation for deriving the examination result will be described with reference to FIGS.

  FIG. 5 is a diagram for explaining an example of conditions for the finite element method analysis. The right side is a mold with a grade of SKD61 and the left side is a grade with a grade of NCF718. The initial temperature of the mold is 300 ° C., and the initial temperature of the material is 1000 ° C. In the one-dimensional analysis, the length of the mold and the material is 100 mm each. The surface opposite the contact surface does not change temperature during this analysis. In order to simulate the hot forging of a large forged product, in this analysis, the mold and the material were brought into contact for 10 seconds during processing, and the heat conduction analysis was performed with a predetermined heat transfer coefficient. Subsequently, the mold was separated from the material, and a heat conduction analysis was performed for 10 seconds.

  FIG. 6 is a diagram displaying an example of the analysis result. In FIG. 6, time is plotted on the horizontal axis, and temperature is plotted on the vertical axis, and changes when the depth of the thermocouple from the mold surface are different are represented by the relationship between time and temperature. In this analysis, the distance A of the thermocouple A28 is 0.5 mm, and the distance B of the thermocouple B29 is 1.0 mm. On the other hand, the distance A when the mold surface is worn by 0.2 mm is 0.3 mm, and the distance B is 0.8 mm. As shown in FIG. 6, it can be seen that the temperature history of each of thermocouple A28 and thermocouple B29 is increased due to wear. The highest temperature is the temperature at the end of forging.

  FIG. 7 is a diagram illustrating an example of a result of inverse analysis of the mold surface temperature without considering the wear amount. In FIG. 7, although the depth of the thermocouple A28 is 0.3 mm and the depth of the thermocouple B29 is 0.8 due to wear, the thermocouple depth data 17 is not changed. The results of inverse analysis of the mold surface temperature are shown as 5 mm and 1.0 mm. The solid line is the correct temperature history of the mold surface obtained by the finite element method analysis, and the broken line is the temperature history of the mold surface obtained by the inverse analysis without considering the 0.2 mm wear of the mold surface. There is a divergence of 10 ° C. or more between the two, and it can be seen that in hot forging that requires high-precision temperature control like forging of Ni-based alloy, it is insufficient measurement accuracy not to consider wear.

  Examining FIG. 6 in detail, it can be seen that the difference in temperature history due to the difference in the depth of the thermocouple from the mold surface is large at the start of forging and is gradually relaxed. FIG. 8 is a diagram showing an example of the first 0.1 second temperature history. The uppermost line is the mold surface temperature, and the second is the temperature history at a depth of 0.1 mm. A temperature history up to a depth of 1.0 mm is shown for every 0.1 mm.

  Among these, the present inventors have found that the influence of wear can be seen by taking a ratio of the thermocouple A28 and the thermocouple B29 for the temperature rising rate in the range of 350 ° C. to 400 ° C.

  FIG. 9 is a diagram for explaining an example of the relationship between the wear amount and the heating rate ratio. In FIG. 9, the amount of wear 30, the depth of thermocouple A28 and thermocouple B29 at that time (after wear), the respective rate of temperature rise (350 ° C. → 400 ° C.), and the ratio (temperature rise of thermocouple A) Speed / temperature increase rate of thermocouple B). In FIG. 9, the heating rate ratio with respect to the change in the amount of wear is 2.7 at 0 mm, 3.1 at 0.1 mm, 3.6 at 0.2 mm, 4 at 0.3 mm. 6.6 and 0.4 mm, it was 6.6. That is, it can be seen from FIG. 9 that the temperature increase rate ratio changes greatly due to wear.

FIG. 10 is a diagram for explaining an example of a relational expression used in the mold wear amount evaluation algorithm 13 of FIG. FIG. 10 shows the relationship between the wear amount and the temperature increase rate ratio in FIG. As shown in FIG. 10, the temperature increase rate ratio / wear amount relational expression 14 between the wear amount and the temperature increase rate ratio can be well approximated by a cubic function (y = ax ³ −bx ² + cx + d). Therefore, the relationship of FIG. 10 obtained in advance is stored in the thermocouple signal processing device 7 as an interpolation equation or approximate polynomial, and the thermocouple A28 and thermocouple B29 are used by the die wear amount evaluation algorithm 13 using the relationship. The amount of wear 30 can be estimated by evaluating the temperature increase rate ratio of these two thermocouples.

  FIG. 11 shows results of inverse analysis of the mold surface temperature when the distance A and the distance B are corrected in consideration of the wear amount 30 and when the distance A and the distance B are not corrected without taking the wear amount 30 into consideration. It is a figure which shows an example. The solid line is the temperature history of the mold surface, and the alternate long and short dash line is the result when reverse analysis is performed without correction. The dotted line is the result when correction is performed and reverse analysis is performed. From these results, it can be seen that high-accuracy measurement can be performed by grasping the change in the depth of the thermocouple A28 and the thermocouple B29 using the temperature increase rate ratio.

  The mold surface temperature history data 10 obtained by the mold wear amount evaluation algorithm 13 is stored in the mold surface temperature history database 11.

<Display screen>
The screen displayed on the display unit 19 of FIG. 1 described above will be described with reference to FIGS.

  FIG. 12 is a diagram showing an example of the temperature history display screen 31 displayed on the display unit 19 of FIG. The temperature history display screen 31 includes a graph display unit 32 and a feature amount display unit 33. The graph display unit 32 takes time on one axis (horizontal axis) and temperature on the other axis (vertical axis), and displays the temperature history of the mold surface with respect to time.

  The feature amount display unit 33 includes a mold maximum temperature display unit 34, a forging end mold temperature display unit 35, a material temperature display unit 36, a heat inflow amount display unit 37 per unit area, a heat flow display button 38, and the like. The

  The mold maximum temperature display unit 34 displays the maximum temperature during forging. The die temperature display unit 35 at the end of forging displays the die surface temperature at the end of forging. The material temperature display unit 36 displays the material temperature calculated from the mold surface temperature using the heat transfer coefficient. In the heat inflow amount display unit 37 per unit area, the heat flow rate calculated from the mold surface temperature history data 10 is calculated per unit area and displayed.

  The heat flow display button 38 is a button for making a transition to the heat flow display screen, and when the heat flow display button 38 is pressed, the heat flow display button 38 makes a transition to a heat flow display screen 39 shown in FIG.

  The feature quantity of the temperature history in the present embodiment is not limited to that shown in the feature quantity display unit 33.

  The temperature history display screen 31 in FIG. 12 displays the result of inverse analysis of the mold surface temperature by the method using the distance A ′ and the distance B ′ obtained by correcting the distance A and the distance B by the wear amount. Further, the mold surface temperature history data 10 accumulated in the mold surface temperature history database 11 is statistically processed to display an average temperature history curve and the like. It is also possible to display the process window and determine if the forging is in the meantime. In addition to being judged by a human, the calculation unit 16 may automatically process and display on the display unit 19 using the hot forging process pass / fail judgment criterion 15.

  FIG. 13 is a diagram illustrating an example of the heat flow display screen 39. The heat flow display screen 39 includes a graph display section 32, a mold maximum temperature display section 34, a forging end mold temperature display section 35, a material temperature display section 36, a heat inflow amount display section 37 per unit area, and a temperature history display. It consists of buttons 40 and the like.

  The graph display unit 32 displays time on the horizontal axis, heat flow on the vertical axis, and changes in heat flow with respect to time. The temperature history display button 40 is a button for making a transition to the temperature history display screen. When the temperature history display button 40 is pressed, the temperature history display button 40 is changed to the temperature history display screen 31 shown in FIG.

  FIG. 14 is a diagram showing an example of the temperature increase rate ratio display screen 41 displayed on the graph display unit 32 shown in FIG. The temperature increase rate ratio display screen 41 displays a change in the temperature increase rate ratio with respect to the order, with the horizontal axis indicating the order and the vertical axis indicating the temperature increase rate ratio. In order, for example, -20 means forging 20 times before the current forging. Actual data has variations, but by calculating the moving average, it is possible to calculate the wear amount 30 that is less affected by variations.

  FIG. 15 is a diagram illustrating an example of a screen displayed on the display unit 19 of FIG. 1 and an example of a comparison display screen 42 with past performance data. The comparison display screen 42 with past performance data includes a graph display unit 32 and a lot comparison display unit 43.

  The graph display unit 32 displays a frequency distribution diagram with respect to temperature, with temperature on the horizontal axis and frequency on the vertical axis. The lot comparison display unit 43 displays the lot average, the standard deviation of the lot, the past average, and the like. As a result, lot-by-lot monitoring is also possible.

<Hot forging products>
The hot forging product manufactured by evaluating with the hot forging process evaluation system of FIG. 1 described above will be described with reference to FIG.

  FIG. 16 is a diagram illustrating an example of a hot forged product manufactured by evaluation using the hot forging process evaluation system of FIG. 1. In the example of FIG. 16, the turbine disk 52 which comprises the jet engine 51 is shown as a hot forging product. The turbine disk 52 is made of, for example, a Ni-base heat-resistant alloy, and the smallest one has a diameter of about φ = 1000 mm.

  In the hot forging of the turbine disk 52, the material is heated to around 1000 ° C. in a precisely temperature-controlled furnace and transported onto a mold for forging, but the material temperature changes every moment due to the high temperature. To do. Therefore, the temperature of the surface of the mold 4 can be measured with high accuracy by using the hot forging process evaluation system of FIG.

<Application of hot forging process evaluation system to hot forging production management>
When the above-described hot forging process evaluation system is applied to the production of hot forging, the number of inspections of hot forged products after manufacturing can be changed using the evaluation results. For example, in the evaluation result, when the deviation from the average is large, it is possible to manage such as increasing the number of forged products to be used for quality inspection and reducing the number of forged products to be used for inspection in a lot close to the average. As a result, it is possible to build a production system that balances cost and quality.

<Effect of one embodiment>
As described above, according to the hot forging process evaluation system in the present embodiment and the product manufactured by evaluation using the hot forging process evaluation system, in the evaluation of the hot forging process, the mold 4 Therefore, the surface temperature of the mold 4 can be measured with high accuracy in consideration of the wear of the mold. In other words, since the temperature of the surface of the mold 4 can be measured with high accuracy throughout the life cycle of the mold 4, the temperature of the forging process can be measured with high accuracy. More specifically, the following effects can be obtained.

  (1) By having a plurality of thermocouples 26 joined to the mold 4 at different depths from the surface of the mold 4, the temperature increase rate ratio / wear amount relational expression 14, the calculation unit 16, and the like, the calculation unit 16, the wear amount of the mold 4 is calculated from the temperature increase rate ratio between the plurality of thermocouples 26 based on the temperature history by the plurality of thermocouples 26 using the temperature increase rate ratio / wear amount relational expression 14. To do. Further, after correcting the depth of the plurality of thermocouples 26 with the calculated wear amount, the temperature of the surface of the mold 4 is calculated by inverse analysis. The hot forging process can be evaluated at the calculated temperature of the surface of the mold 4.

  (2) The thermocouple depth data 17 and the thermocouple temperature of the thermocouple temperature history database 9 according to the mold surface temperature calculation algorithm 12 by having the mold surface temperature calculation algorithm 12, the mold wear amount evaluation algorithm 13, and the like. The die surface temperature history data 10 on the surface of the die 4 can be calculated using the history data 8. According to the die wear amount evaluation algorithm 13, the wear amount of the die 4 can be calculated using the thermocouple temperature history data 8 of the thermocouple temperature history database 9 and the data of the temperature increase rate ratio / wear amount relational expression 14. it can. And in the calculating part 16, the quality of the hot forging process can be judged according to the hot forging process quality judgment standard 15 using the die surface temperature history data 10 considering the wear amount of the die 4.

  (3) By having the display unit 19 and the like, the mold surface temperature history data 10, the thermocouple temperature history data 8, the thermocouple depth data 17 and the like can be displayed. Further, the display unit 19 can display a curve such as an average temperature history as a result of statistically processing the mold surface temperature history data 10.

  (4) The thermocouple 26 has two sets of thermocouples A28 and B29 having different depths, so that the thermocouple depth after wear of each thermocouple and the rate of temperature increase between the thermocouples Thus, the temperature increase rate ratio / wear amount relational expression 14 can be derived.

  (5) Since the number of inspections of hot forged products after manufacturing can be changed based on the evaluation results by the hot forging process evaluation system, production with a balance between cost and quality in hot forging production management A system can be established.

  (6) A high quality product can be manufactured by evaluating with a hot forging process evaluation system.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.

  For example, in the above embodiment, the hot forging process of the jet engine turbine disk has been described as an example, but the present invention is not limited to this, and the mold temperature is maintained at about 200 to 300 ° C. It can be widely applied to general hot forging processes in general.

1 ... Material, 2 ... Lower mold, 3 ... Upper mold, 4 ... Mold, 5 ... Thermocouple unit,
6 ... Receiver,
DESCRIPTION OF SYMBOLS 7 ... Thermocouple signal processing apparatus, 8 ... Thermocouple temperature history data, 9 ... Thermocouple temperature history database, 10 ... Mold surface temperature history data, 11 ... Mold surface temperature history database, 12 ... Mold surface temperature calculation algorithm , 13 ... Die wear amount evaluation algorithm, 14 ... Temperature increase rate ratio / wear amount relational expression, 15 ... Hot forging process pass / fail judgment criteria, 16 ... Calculation unit, 17 ... Thermocouple depth data,
18 ... operation part, 19 ... display part, 20 ... keyboard, 21 ... mouse,
22 ... Thermocouple unit mounting portion, 23 ... Thermocouple introduction portion, 24 ... Relief processing portion, 25 ... Thermocouple head, 26 ... Thermocouple, 27 ... Welding portion, 28 ... Thermocouple A, 29 ... Thermocouple B, 30 … Amount of wear,
31 ... Temperature history display screen, 32 ... Graph display section, 33 ... Feature quantity display section, 34 ... Mold maximum temperature display section, 35 ... Mold temperature display section at the end of forging, 36 ... Material temperature display section, 37 ... Unit Heat inflow amount display area per area, 38 ... heat flow rate display button,
39 ... Heat flow rate display screen, 40 ... Temperature history display button,
41 ... Temperature increase rate ratio display screen,
42 ... Comparison display screen with past performance data, 43 ... Lot comparison display section,
51 ... Jet engine, 52 ... Turbine disk.

Claims (7)

The system calculates the temperature of the mold surface by inverse analysis using the temperature history of the temperature measuring device, and evaluates the hot forging process at the calculated temperature of the mold surface,
A plurality of the temperature measuring instruments joined to the mold at different depths than the surface of the mold;
The temperature increase rate ratio between the plurality of temperature measuring devices, and the temperature increase rate ratio / abrasion amount relationship information indicating the relationship between the temperature increase rate ratio and the amount of wear of the mold with respect to the temperature increase rate ratio,
Using the temperature rise rate ratio / wear amount relation information, the wear amount of the mold is calculated from the temperature rise rate ratio between the plurality of temperature measuring devices based on the temperature history by the plurality of temperature measuring devices. Then, after correcting the depths of the plurality of temperature measuring devices with the calculated wear amount, the surface temperature of the mold is calculated by inverse analysis, and the hot forging process is performed at the calculated surface temperature of the mold. An arithmetic unit for evaluating
Having a hot forging process evaluation system. The hot forging process evaluation system according to claim 1, further comprising:
A measuring device temperature history database for storing temperature history data by the plurality of temperature measuring devices;
A mold surface temperature history database for storing temperature history data of the mold surface;
A mold surface temperature calculation algorithm for calculating temperature history data of the surface of the mold using depth data of the plurality of temperature measuring instruments and temperature history data of the measuring instrument temperature history database;
A mold wear amount evaluation algorithm for calculating a wear amount of the mold using temperature history data of the measuring device temperature history database and data of the temperature increase rate ratio and wear amount relation information;
Having a hot forging process evaluation system. The hot forging process evaluation system according to claim 2, further comprising:
A hot section having a display unit that displays at least one of the temperature history data of the surface of the mold, the temperature history data by the plurality of temperature measuring devices, and the depth data of the plurality of temperature measuring devices. Forging process evaluation system. In the hot forging process evaluation system according to claim 3,
The said display part is a hot forging process evaluation system which displays the result of having statistically processed the temperature history data of the surface of the said metal mold | die. In the hot forging process evaluation system according to claim 4,
Each of the plurality of temperature measuring devices has two sets of thermocouples, the first thermocouple is joined to the mold at a first depth from the surface of the mold, and the second thermocouple is A hot forging process evaluation system that is joined to the mold at a second depth different from the first depth from the surface of the mold. In the hot forging process evaluation system according to claim 1,
A hot forging process evaluation system capable of changing the number of inspections of a hot forged product after manufacture based on an evaluation result of a hot forging process by the arithmetic unit.   A product manufactured by being evaluated by the hot forging process evaluation system according to claim 1.