JP2005246471A - Temperature simulation method of body to be cooled by spray cooling and decision method for cooling condition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature simulation method or a decision method for cooling condition which is generalized and applicable to a variety of cooling conditions, in the temperature simulation during cooling of a body to be cooled by supplying a cooling fluid, and in the decision of a cooling condition to satisfy a target cooling specification. <P>SOLUTION: The temperature simulation method estimates a temperature distribution when the body to be cooled is cooled by the cooling fluid supplied from a nozzle. The temperature simulation method comprises a Reynolds number calculation step of calculating the Reynolds number Re of the cooling fluid flowing inside the nozzle, a hc distribution calculation step to obtain the hc distribution that is a distribution of thermal conductivity coefficient of the cooling fluid on the outer surface of the body to be cooled, based on the calculated Reynolds number Re, and a temperature distribution calculation step of obtaining the temperature distribution in a forging die based on the distribution of the thermal conductivity coefficient on the outer surface of the forging die. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a temperature distribution simulation method for estimating a temperature distribution when a cooled object is cooled by a cooling fluid supplied from a nozzle, and a cooling condition determination method that satisfies a target cooling specification.

  Conventionally, for example, as a method of simulating the temperature distribution when cooling a casting mold by supplying a cooling fluid, it is based on the position of the cooling point that is the supply source of the cooling fluid, the injection direction, the injection projection shape, and the cooling capacity. In some cases, the heat transfer coefficient between the outer surface of the casting mold and the outside is obtained. In this simulation method, the temperature distribution of the casting mold is estimated based on the heat transfer coefficient obtained as described above.

JP 2003-170269 A

  However, the conventional temperature simulation method has the following problems. That is, among the position for specifying the cooling point, the injection direction, the injection projection shape, and the cooling capacity, in particular, the cooling capacity is a characteristic value that depends on the type of cooling fluid and the injection amount. Therefore, in the above temperature simulation method, when the type of the cooling fluid is changed or the injection amount is changed, it is necessary to actually measure the cooling capacity each time.

  The present invention has been made in view of the above-described conventional problems. In the temperature simulation when cooling the object to be cooled by supplying the cooling fluid and the determination of the cooling condition satisfying the target cooling specification, there are various. It is an object of the present invention to provide a generalized temperature simulation method or a cooling condition determination method that can be applied to cooling conditions.

1st invention is the temperature simulation method which estimates the temperature distribution at the time of cooling a to-be-cooled body with the cooling fluid supplied from the nozzle,
A Reynolds number calculating step of calculating the Reynolds number of the cooling fluid flowing in the nozzle;
An hc distribution calculating step of calculating an hc distribution that is a distribution of a heat transfer coefficient with the cooling fluid on the outer surface of the cooled object, based on the Reynolds number;
A temperature simulation method characterized by performing a temperature distribution calculation step of obtaining a temperature distribution of the inner and outer surfaces of the object to be cooled based on the hc distribution (claim 1).

  According to the temperature simulation method of the first aspect of the invention, the distribution of the heat transfer coefficient between the cooling fluid on the outer surface of the object to be cooled is determined according to the Reynolds number of the cooling fluid flowing in the nozzle for spray cooling It is a method based on new knowledge that the inventors have acquired through experiments, analysis, and the like.

That is, in the temperature simulation method, in the Reynolds number calculation step, the Reynolds number of the cooling fluid flowing in the nozzle is calculated, and in the hc distribution calculation step performed thereafter, the Reynolds number is calculated based on the calculated Reynolds number. The hc distribution, which is the distribution of the heat transfer coefficient with the cooling fluid on the outer surface of the object to be cooled, is obtained.
And the heat distribution analysis method and heat transfer analysis method which belong to heat transfer engineering etc. are used, and the temperature distribution of the said to-be-cooled body is calculated | required from distribution of the said heat transfer coefficient of the outer surface of the said to-be-cooled body.

  As described above, the temperature simulation method of the first invention focuses on the Reynolds number of the cooling fluid in the nozzle, and quantifies the heat transfer coefficient of the outer surface of the cooled object based on the Reynolds number. This is an epoch-making temperature simulation method.

A second invention is a method for determining a cooling condition when cooling an object to be cooled by a cooling fluid supplied from a nozzle.
A target setting step for setting a specific point in the body to be cooled and setting a target temperature that is a temperature of the specific point after a predetermined time;
An hc distribution determination step for determining an hc distribution, which is a distribution of a heat transfer coefficient between the cooling fluid and the cooling fluid on the outer surface of the object to be cooled necessary to achieve the target temperature;
A Reynolds number determining step for determining a Reynolds number of the cooling fluid flowing in the nozzle based on the hc distribution;
Based on the Reynolds number, at least one of the nozzle inner diameter, the flow rate of the cooling fluid in the nozzle, the flow rate, the temperature, the kinematic viscosity coefficient, and the cooling condition defined by the type of the cooling fluid is determined. Then, a specification determining step for determining the cooling condition is performed. (Claim 6)

  In the cooling condition determination method according to the second aspect of the invention, first, the target setting step is performed, the specific point in the cooled object is set, and the target temperature that is the temperature of the specific point after a predetermined time is set. Set. In the hc distribution determination step, the outer surface of the object to be cooled is realized by using a heat conduction analysis method belonging to heat transfer engineering or the like, a heat transfer analysis method, or the like to achieve the set target temperature. The hc distribution, which is a distribution of the necessary heat transfer coefficient, is determined.

  Thereafter, the Reynolds coefficient determination step is performed, and the Reynolds number of the cooling fluid flowing in the nozzle is determined based on the hc distribution. And further, the specification determining step is performed, and among the cooling conditions defined by the nozzle inner diameter of the nozzle, the flow velocity of the cooling fluid in the nozzle, the flow rate, the temperature, the kinematic viscosity coefficient, and the type of the cooling fluid, The cooling condition is determined by determining at least one of them.

  For example, when a cooling device such as a nozzle is newly designed, the nozzle diameter, the flow rate of the cooling fluid, the temperature, and the like can be determined within a range that satisfies the determined Reynolds number. Alternatively, for example, when an existing cooling device is used and the nozzle diameter and the type of the cooling fluid are fixed, the flow rate of the cooling fluid is determined based on the determined Reynolds number. And other specifications such as its temperature can be determined.

As described above, the second invention pays attention to the relationship between the Reynolds number and the heat transfer coefficient between the cooling fluid on the outer surface of the object to be cooled and uses the relationship to set the cooling condition. To decide.
That is, using a general analysis method belonging to heat transfer engineering or the like, the hc distribution required on the outer surface of the cooled object is obtained from the target temperature, and then the Reynolds coefficient is determined from the hc distribution. To do. The cooling conditions are determined efficiently based on the Reynolds coefficient.
The specific point may be on the outer surface of the body to be cooled or may be on the inside, or only one or a plurality of specific points may be set.

In the first and second inventions, the object to be cooled requires cooling of, for example, a forging die, a casting die, a cutting machine, a lathe machine, a workpiece to be machined, and the like. There are various subjects to do.
In the first aspect of the invention, the object to be cooled is preferably a forging die for forging press molding.
In this case, the temperature simulation of the forging die can be performed with high accuracy, and the temperature management of the forging die can be appropriately performed. And in the said forging die which implemented temperature control appropriately, the die lifetime can be lengthened and production cost can be suppressed.

  Further, in the hc distribution calculating step, a first map representing a relationship between the Reynolds number and the heat transfer coefficient at the water flow center of the nozzle on the outer surface of the object to be cooled, and from the water flow center, It is preferable to obtain the hc distribution by using a second map representing a relationship between a distance and a heat transfer coefficient ratio that is a ratio to the heat transfer coefficient at the water flow center.

In this case, by combining the first map and the second map, the hc distribution can be obtained efficiently when the cooling fluid is supplied from the nozzle to cool the object to be cooled. .
And if the said hc distribution is calculated | required, the temperature distribution of the said to-be-cooled body can be estimated efficiently using a general heat conduction analysis method, a heat transfer analysis method, etc. after that.

In addition, it is preferable that the first map and the second map are corrected using an index representing a degree of spread of the cooling fluid supplied from the nozzle.
When the degree of spread of the cooling fluid supplied from the nozzle is changed, the hc distribution around the water flow center may change as well as the heat transfer coefficient at the water flow center.

  Therefore, when the first and second maps are corrected according to the degree of spread of the cooling fluid as described above, the hc distribution regardless of the degree of spread of the cooling fluid supplied to the object to be cooled. Can be calculated with high accuracy.

Further, it is preferable that the second map is corrected by the curvature of the outer surface of the object to be cooled.
If the curvature of the outer surface of the object to be cooled changes, the hc distribution around the water flow center may change even if the heat transfer coefficient at the water flow center remains unchanged.
Therefore, when the first map is corrected according to the curvature of the outer surface of the cooled object as described above, the hc distribution is accurately determined regardless of the curvature of the outer surface of the cooled object. Can be calculated.

In the second invention, it is preferable that the object to be cooled is a forging die for forging.
In this case, the cooling conditions for appropriately cooling the forging die can be determined efficiently. And if the said forging die is cooled according to this cooling condition, the die lifetime can be extended.

  Further, in the Reynolds number determination step, a first map representing a relationship between the Reynolds number and the heat transfer coefficient at the water flow center of the nozzle on the outer surface of the object to be cooled, and from the water flow center, It is preferable to obtain the Reynolds number using a second map that represents the relationship between the distance and a heat transfer coefficient ratio that is a ratio to the heat transfer coefficient at the water flow center.

In this case, by combining the first map and the second map, the hc distribution can be efficiently obtained when the cooling fluid is supplied from the nozzle to the cooled object and cooled. it can.
And if the said hc distribution is calculated | required, the temperature distribution of the said to-be-cooled body can be estimated efficiently after that.

In addition, it is preferable that the first map and the second map are corrected using an index representing a degree of spread of the cooling fluid supplied from the nozzle.
In this case, the hc distribution can be accurately determined regardless of the extent of the cooling fluid supplied to the cooled object.

The second map is preferably corrected by the curvature value of the outer surface of the body to be cooled.
In this case, the hc distribution can be accurately determined regardless of the curvature of the outer surface of the cooled object.

The second map is corrected by a nozzle inclination angle that is an angle formed between a normal direction of the outer surface of the cooled object and a nozzle direction in which the nozzle blows the cooling fluid. (Claim 11).
In this case, the hc distribution can be accurately determined regardless of the spray angle.

(Example 1)
This example relates to a temperature simulation method for estimating a temperature distribution when a forging die for hot forging is cooled by a cooling fluid supplied from a nozzle. This will be described with reference to FIGS.
This example relates to a temperature simulation method for estimating a temperature distribution when cooling an object to be cooled (in this example, a forging die not shown) with a cooling fluid supplied from a nozzle.
In this temperature simulation method, the Reynolds number calculation step of calculating the Reynolds number Re of the cooling fluid flowing in the nozzle, and the heat transfer between the cooling fluid on the outer surface of the object to be cooled based on the calculated Reynolds number Re. An hc distribution calculating step for calculating an hc distribution, which is a coefficient distribution, and a temperature distribution calculating step for obtaining the temperature distribution on the inner and outer surfaces of the forging die based on the distribution of the heat transfer coefficient on the outer surface of the forging die. .
This content will be described in detail below.

  This example is a temperature simulation method for estimating a temperature distribution when cooling a forging die used in a hot forging press. This temperature simulation method is based on new knowledge newly found by the inventors through verification experiments and analysis work over many years. This new finding is that the Reynolds number Re of the cooling fluid flowing in the nozzle is closely related to the heat transfer coefficient with the cooling fluid on the outer surface of the forging die, and the above is based on the Reynolds number Re. This is the knowledge that the heat transfer coefficient can be obtained. This will be described below.

  When the cooling fluid is supplied from the nozzle to cool the forging die, as shown in FIG. 1, the heat transfer coefficient of the outer surface changes depending on the Reynolds number Re of the cooling fluid flowing in the nozzle. In the figure, the measured value of the heat transfer coefficient 1 second after the start of cooling is shown as a plot 1a (indicated by solid ◇), and the solid line 1b shows an approximate curve obtained by the least square method.

  In the figure, the horizontal axis represents the Reynolds number Re of the cooling fluid flowing in the nozzle, and the vertical axis represents the cooling fluid at a position corresponding to the water flow center by the nozzle on the outer surface of the forging die. The heat transfer coefficient is shown. Furthermore, in the same figure, the case where a cooling fluid is supplied to the outer surface which exhibits a substantially planar shape is shown.

  That is, according to the figure, the heat transfer coefficient at the center of the water flow in the outer surface of the forging die changes depending on the Reynolds number Re. And, according to various demonstration experiments by the inventors, the heat transfer coefficient does not depend on individual values such as nozzle diameter, cooling fluid flow velocity, flow rate, cooling fluid temperature, etc., but only Reynolds number Re. It turns out that it depends. That is, as long as the Reynolds number Re is substantially the same, the heat transfer coefficient at the water flow center in the outer surface of the forging die is substantially constant.

Further, the heat transfer coefficient on the outer surface of the forging die changes according to the distance from the water flow center as shown in FIG. In the figure, the horizontal axis defines a dimensionless number obtained by dividing the distance r from the water flow center by the nozzle diameter D, and the vertical axis indicates the position at each position where the heat transfer coefficient at the water flow center is 1. The heat transfer coefficient is shown.
The change in the heat transfer coefficient around the water flow center is affected by the Reynolds number of the cooling fluid flowing in the nozzle. That is, when the Reynolds number Re is in the range of 47000 to 70000 (in the figure, the plot 2a (indicated by white circles)) is in the range of Re = 10000 to 140000 (in the figure). Compared with the plot 2b (indicated by x), the decrease in the heat transfer coefficient when being away from the water flow center is suppressed.

Further, the inventors conducted an experiment in which the temperature of the forging die as the body to be cooled was changed, and the relationship between the Reynolds number and the heat transfer coefficient (the relationship shown in FIGS. 1 and 2) is shown in FIG. As shown, it has been found that a substantially constant relationship is exhibited without depending on the temperature of the forging die.
According to FIG. 3 in which the measured value of the above experiment is represented by plot 3a (indicated by solid squares) and the calculated value by the temperature simulation method of this example is represented by plot 3b (indicated by solid squares), forging The measured values and the calculated values agree very well regardless of the mold temperature. This indicates that the relationship between the Reynolds number Re and the heat transfer coefficient is substantially constant regardless of the temperature of the forging die.
In the figure, the horizontal axis defines the temperature of the forging die before the start of cooling, and the vertical axis defines the temperature of the forging die one second after the start of cooling.

Furthermore, the inventors conducted an experiment in which the type and temperature of the cooling fluid for cooling the forging die were changed, and the relationship between the Reynolds number and the heat transfer coefficient (the relationship shown in FIGS. 1 and 2) was obtained. It has been found that a substantially constant relationship is exhibited regardless of the temperature of the cooling fluid supplied.
As a cooling fluid, water at 23 ° C. (plot 4a (shown by filled circles)), water at 40 ° C. (plot 4b (shown by filled Δ marks)), water at 10 ° C. (plot 4c (filled squares) 23) Lubricant A at 23 ° C. (plot 4d (indicated by white circles))) and 10 ° C. Lubricant A (plot 4e ( According to FIG. 4 showing the results of the above experiments using the same lubricant A at 40 ° C. (plot 4f (indicated by white triangle Δ))), the kind of cooling fluid is shown. Even if the temperature is changed, the relationship between the Reynolds number and the heat transfer coefficient is almost constant.
In the figure, the horizontal axis represents the Reynolds number Re, and the vertical axis represents the heat transfer coefficient at the water flow center.

  Furthermore, when applying the temperature simulation method in this example, a demonstration experiment is performed to verify the validity. As shown in FIG. 5, this demonstration experiment uses a body to be cooled 10 having a substantially cylindrical shape with a height of 50 mm and a diameter of 50 mm. In the demonstration experiment, a temperature change was measured when the cooling fluid was supplied to the cooled object 10 from the nozzle 20 disposed so as to face the circular end surface 101 and cooled.

The nozzle 20 of the demonstration experiment is disposed at a position 60 mm away from the circular end surface 101 along the axis 102 of the cooled object 10 having a substantially cylindrical shape. The nozzle 20 is configured to cause the cooling fluid to flow out along the axial direction 102 so that the water flow center is formed substantially at the center of the circular end surface 101 of the fluid to be cooled 10.
The nozzle 20 has an opening tip with an inner diameter of Φ3.4 mm, and is configured to supply a cooling fluid made of water from the opening tip at a flow rate of 5.3 m per second (flow rate 3 liters / min). It is. At this time, the Reynolds number of the cooling fluid flowing in the nozzle 20 was 10056.

FIG. 6 shows the temperature change inside the cooled object 10 by this demonstration experiment. In this figure, the depth on the axis 20 of the body to be cooled 10 having a substantially cylindrical shape is 0.5 mm (plot 6a (shown by hatching 印)), 2 mm (plot 6b (shown by white triangle))). The time-dependent change in temperature at each measurement point of 4 mm (plot 6c (indicated by white squares)) and 25 mm (plot 6d (indicated by white squares)) is shown.
In the figure, the horizontal axis indicates the cooling time, and the vertical axis indicates the temperature. Furthermore, in the same figure, in addition to each actual measurement value, the temperature at each measurement point estimated using the temperature simulation method of this example is shown by a solid line. In addition, the above results are substantially the same even when the distance between the nozzle 20 and the cooled object 10 is changed from 5 to 200 mm.

  According to the figure, it can be seen that the actual measurement value indicated by the solid line and the plot values 6a to 6d obtained by the temperature simulation of this example are in good agreement. This indicates the validity of the temperature simulation method of this example in which the temperature is estimated by obtaining the heat transfer coefficient of the outer surface of the cooled object 10 based on the Reynolds number Re. Therefore, the temperature distribution of the cooled object 10 can be estimated with high accuracy using the temperature simulation method of this example.

As described above, the findings found by the inventors are that the Reynolds number Re and the heat transfer coefficient have a close correlation, and the correlation may vary depending on the temperature of the object to be cooled. In addition, there is little risk of fluctuating depending on the type of water and the type of cooling fluid in which the lubricant is diluted to about 10% by volume in water, the temperature thereof, and the like.
Based on the above knowledge, the temperature simulation method of the present example of calculating the heat transfer coefficient of the cooled object from the Reynolds number Re of the cooling fluid is an excellent simulation method having generality with a wide range of application. . Therefore, according to the temperature simulation method of the present example, the cooling temperature of the object to be cooled can be accurately estimated regardless of the type of the cooling fluid, its temperature, and the like.

  Strictly speaking, the cooling capacity when the cooling fluid is sprayed is slightly dependent on the type and temperature of the lubricant. Therefore, if the above correlation is obtained individually according to the type and temperature of the lubricant, the temperature estimation accuracy according to the temperature simulation method of this example can be further improved.

Next, the contents of the temperature simulation method of this example will be described. In this example, the cooling temperature of the forging die exhibiting a planar outer surface is estimated.
In this temperature simulation method, as described above, the Reynolds number calculation step of calculating the Reynolds number Re of the cooling fluid flowing in the nozzle, and the heat between the cooling fluid on the outer surface of the forging die based on the Reynolds number Re. An hc distribution calculating step for obtaining an hc distribution, which is a distribution of the transfer coefficient, and a temperature distribution calculating step for obtaining the temperature distribution on the inner and outer surfaces of the forging die based on the distribution of the heat transfer coefficient on the outer surface of the forging die. .
In this example, the temperature of the forging die at the start of cooling is set to 300 ° C. Then, a 23 ° C. cooling fluid made of water was supplied from a nozzle having an inner diameter of Φ3.4 mm toward the forging die at a flow rate of 5.3 m / second (flow rate: 3 liters / minute).

  The Reynolds number calculation step is a step of calculating the Reynolds number Re of the cooling fluid in the nozzle when supplying the cooling fluid from the nozzle to the object to be cooled. In this example, the Reynolds number Re was calculated by the following equation using the nozzle diameter D, the kinematic viscosity coefficient ν according to the temperature, the flow velocity V of the cooling fluid, the flow rate Q, and the nozzle cross-sectional area S.

The Reynolds number calculation formula used in this example is as follows.
That is,
Re = DV / ν
This is a calculation formula.
Or, using the calculation formula of Re = DQ / (Sν),
When the opening shape of the nozzle 20 is round is because S = πD ^2/4,
A calculation formula of Re = 4Q / (πDν) can also be used.
However, ν in each calculation formula is a value determined by the temperature and the type of the cooling fluid.

The hc distribution calculating step is a step of obtaining an hc distribution that is a distribution of the heat transfer coefficient on the outer surface of the object to be cooled based on the Reynolds number Re. In this step, a first map (relationship defined in FIG. 1) showing the relationship between the Reynolds number Re and the heat transfer coefficient of the nozzle water flow center in the forging die, and heat transfer with respect to the deviation from the water flow center. The hc distribution is examined on the basis of a second map (the relationship defined in FIG. 2) representing the change of the coefficient.
As described above, when the first map and the second map are combined, the distribution of the heat transfer coefficient on the outer surface of the forging die when the cooling fluid is supplied from the nozzle to the forging die for cooling is highly accurate. In addition, it can be obtained with high efficiency.

  Then, if the temperature distribution calculating step is performed next, the temperature distribution of the forging die can be obtained based on the hc distribution that is the distribution of the heat transfer coefficient on the outer surface of the forging die. That is, once the hc distribution is obtained, a general heat conduction analysis method, a heat transfer analysis method, or the like can be performed to estimate the temperature distribution of the forging die with high accuracy.

As described above, according to the temperature simulation method of this example, the temperature distribution of the forging die can be estimated extremely efficiently analytically.
Instead of this example, the cooling fluid may be supplied from a plurality of nozzles toward the same water flow center. In this case, the temperature simulation can be performed in the same manner as in this example, using the total Reynolds number obtained by adding the Reynolds numbers of the nozzles.

(Example 2)
This example is an example in which an appropriate cooling condition for cooling the forging die is determined based on the temperature simulation method of the first embodiment.
The cooling condition determination method of this example is based on the knowledge that the Reynolds number Re and the heat transfer coefficient have a close correlation, as in the first embodiment. This will be described with reference to FIGS.

  In the cooling condition determination method of this example, a specific point in the forging die is set, a target setting step for setting a target attainment temperature that is a temperature at the specific point after a predetermined time, and a target attainment temperature are required to be realized. A hc distribution determining step for determining a hc distribution which is a distribution of a heat transfer coefficient with the cooling fluid on the outer surface of the object to be cooled, and a Reynolds number Re of the nozzle which supplies the cooling fluid based on the heat transfer coefficient A step of determining the Reynolds number, and based on the Reynolds number, cooling defined by the nozzle inner diameter, the flow velocity, the flow rate, the temperature, the kinematic viscosity coefficient, and the type of the cooling fluid in the nozzle. A specification determining step of determining at least one of the conditions and determining the cooling condition is performed.

In the cooling condition determination method of this example, first, the target setting step is performed to set a specific point in the forging die and set a target temperature that is the temperature of the specific point after a predetermined time.
The specific point may be a position on the outer surface of the forging die or an internal position, and only one point or a plurality of points may be set.

  Next, in the hc distribution determining step, an hc distribution that is a distribution of the heat transfer coefficient of the outer surface of the forging die necessary for realizing the target temperature at the set specific point is determined. That is, in this step, an hc distribution that can achieve the set target temperature is obtained. In the present example, the hc distribution is determined using a general heat conduction analysis method, a heat transfer analysis method, or the like.

Then, in the Reynolds number determination step, the Reynolds number Re of the cooling fluid flowing in the nozzle is determined based on the hc distribution obtained as described above.
Here, a first map showing the relationship between the Reynolds number Re of the cooling fluid flowing in the nozzle and the heat transfer coefficient at the water flow center of the nozzle on the outer surface of the forging die (see FIG. 1 described in the first embodiment). And the second map showing the change in the heat transfer coefficient with respect to the distance from the water flow center (the relationship defined in FIG. 2 described in the first embodiment), and the hc distribution. From this, the Reynolds number Re was determined.
That is, in this example, the Reynolds number Re is obtained from the hc distribution according to the reverse procedure of the first embodiment.

Then, in the specification determination process in the subsequent process, the cooling condition for supplying the cooling fluid from the nozzle is determined using the calculation formula of the Reynolds number Re shown in the first embodiment.
In this example, a fixed value such as the kinematic viscosity coefficient depending on the nozzle diameter, the type of cooling fluid, the flow rate, and the temperature is substituted into the above formula, and the variable specification values of the flow rate and temperature are used as the cooling conditions. Decided.

As described above, in this example, the distribution of the heat transfer coefficient of the forging die that achieves the set target temperature is determined, and the Reynolds number Re is calculated based on the heat transfer coefficient. And the cooling conditions which supply a cooling fluid based on this Reynolds number Re were determined. If the cooling condition of the cooling fluid is determined in this way, the above cooling condition can be determined analytically and efficiently without depending on the actual matching at the processing site.
Other configurations and operational effects are the same as those in the first embodiment.

(Example 3)
This example is an example in which correction is performed on the outer surface shape (curvature) of the object to be cooled in the first and second embodiments. This will be described with reference to FIGS. 2, 7, and 8. FIG.
In this example, the heat transfer coefficient is corrected by the curvature of the outer surface of the forging die that supplies the cooling fluid. That is, this example is an example of a temperature simulation method that takes into consideration the effect of the heat transfer coefficient decreasing as the curvature of the outer surface of the forging die decreases (from a flat surface to a curved surface).

In this example, it replaces with the 2nd map (The map showing the relationship of the change of the heat transfer coefficient with respect to the distance from a water flow center. That is, the relationship prescribed | regulated in FIG. 2) used in Example 1 and Example 2. FIG. 7 and FIG. 8, the second map of this example including curvature correction is used.
Therefore, according to this example, a highly accurate temperature simulation or a highly accurate cooling condition can be determined regardless of the curvature of the outer surface of the forging die.

As shown in FIG. 7, a plane having an infinite curvature (plot 7a (shown by filled squares)) and a convex curved surface having a curvature R = 25 mm (plot 7b (shown by filled squares)). In comparison, the flow distribution of the cooling fluid on the outer surface centered on the water flow center is different. In other words, in the case of a forging die made of a curved surface, since the curvature becomes small, most of the water flow flows out of the surface of the forging die relatively quickly, so the flow rate with respect to the distance from the center of the water flow decreases. Yes.
In the figure, the horizontal axis indicates the dimensionless number obtained by dividing the distance from the water flow center by using the nozzle diameter, and the vertical axis indicates the flow rate ratio at each position when the flow rate at the water flow center is 1. Show.

  Then, due to the difference in the flow rate of the cooling fluid flowing along the outer surface of the forging die, as shown in FIG. )) And there is a difference in the distribution of heat transfer coefficient. That is, in the case of a curved surface (plot 8b (indicated by solid ◇)), since the flow rate of the cooling fluid is small with respect to the distance from the water flow center, the heat transfer coefficient is also small.

In this example, considering that the distribution of the heat transfer coefficient differs depending on whether the cooling surface is a curved surface or a flat surface, the temperature distribution is estimated by correcting this difference (Example 1), or the heat transfer coefficient. (Example 2) is calculated.
Therefore, in the temperature simulation method of the first embodiment, the temperature estimation accuracy can be improved. Similarly, in the determination of the cooling condition by the method for determining the cooling condition of the second embodiment, the determination accuracy can be improved.
Other configurations and operational effects are the same as those in the first or second embodiment.

Example 4
In this example, the steady temperature of a forging die in which hot forging is repeatedly performed is estimated based on Example 1. The contents will be described with reference to FIGS.
In this example, a cooling fluid is supplied from a nozzle and cooled with respect to a forging die that repeatedly performs hot forging at a frequency of 1 Hz.

As shown in FIG. 9, the temperature of the forging die in the unsteady section 9 a after the start of processing gradually increases while repeating the temperature increase due to processing heat and the temperature decrease due to cooling. After that, when the magnitude of the processing heat and the magnitude of the cooling heat are substantially balanced, a transition is made to a steady state (steady section 9b) in which the average temperature of the forging die is substantially constant.
In the figure, time is defined on the horizontal axis, and the temperature of the forging die is defined on the vertical axis.

Here, if the temperature simulation method of the first embodiment is used, the average temperature of the forging die and the fluctuating temperature range can be accurately estimated over the entire range from the unsteady section 9a to the steady section 9b.
Specifically, as shown in FIGS. 9 and 10, first, the minimum temperature in the steady section 9b, that is, the temperature immediately before machining in the machining cycle is set as a variable Tmin.
Next, using the energy conservation law, when the temperature of the forging die immediately before pressing is Tmin, the ultimate temperature Tmax after the processing heat at the time of hot forging is input is calculated.

Thereafter, the heat transfer coefficient of the outer surface of the forging die when supplying the cooling fluid toward the forging die having the temperature Tmax is obtained, and the magnitude of the cooling heat taken away by the cooling is calculated.
Then, the calculation is repeated while changing the variable Tmin, and the temperature Tmin at which the magnitude of the processing heat substantially matches the magnitude of the cooling heat and the ultimate temperature Tmax of the forging die at that time are obtained.

  Thus, if the temperature simulation method of Example 1 is used, the temperature change range (Tmin to Tmax) of the forging die and the fluctuation due to the processing repetition when the hot forging process is performed at a constant cycle will be accurately estimated. be able to. And if the temperature change of a forging die can be estimated, the lifetime of the forging die used for a process can be estimated accurately.

Further, if the temperature range to be maintained from the die life required for the forging die is determined in advance, the cooling conditions for supplying the cooling fluid from the above temperature range using the cooling condition determination method of Example 2 can be accurately set. You can also decide well.
Other configurations and operational effects are the same as those in the first or second embodiment.

(Example 5)
This example is an example in which a correction based on the degree of spread when the cooling fluid is supplied from the nozzle 20 is added to the first and second embodiments. The contents will be described with reference to FIGS. Here, in this example, the degree of spread of the cooling fluid is defined using a dimensionless number R / D obtained by dividing the radius R of the spray region by the nozzle inner diameter D as shown in FIG.

  As shown in FIG. 12, when the R / D representing the extent of the cooling fluid sprayed from the nozzle 20 is increased (when the sprayed area is enlarged), the heat transfer coefficient at the center of the water flow tends to decrease. Further, as shown in FIG. 13, when the R / D representing the degree of spread of the cooling fluid is increased, the heat transfer coefficient with respect to the distance r / D from the center of the water flow is stabilized to a large region, but the sprayed surface to the cooled object It tends to decrease rapidly outside.

Therefore, in this example, according to the R / D, the first map (the map showing the relationship between the Reynolds number Re and the heat transfer coefficient at the center of the water flow. That is, the relationship defined in FIG. 1) and the above. The second map (a map showing the change of the heat transfer coefficient with respect to the distance from the water flow center, ie, the relationship defined in FIG. 2) was corrected.
Therefore, according to this example, a highly accurate temperature simulation or a highly accurate cooling condition can be determined regardless of the extent of the cooling fluid supplied from the nozzle 20.

In addition, instead of this example expressing the degree of spread of the cooling fluid by R / D, the degree of spread is the spread angle or spray density (the nozzle outlet flow rate is the amount reached per unit area sprayed on the surface of the object to be cooled). It is also possible to express it using an index such as
Other configurations and operational effects are the same as those in the first or second embodiment.

(Example 6)
This example is an example in which the nozzle direction is inclined with respect to the surface of the forging die 10 in Example 1 and Example 2. The contents will be described with reference to FIGS.
In this example, as shown in FIG. 14, the deviation angle (angle formed by both directions) of the nozzle direction with respect to the normal direction of the surface of the forging die 10 is defined as the nozzle inclination angle θ. In FIG. 15, the horizontal axis defines the distance r / D from the water flow center 11, and the vertical axis defines the change in the heat transfer coefficient.
In the figure, the ratio of the heat transfer coefficient at θ = 0 ° in the water flow center 11 and the heat transfer coefficient at the position 12 (see FIG. 14) where the distance from the water flow center 11 is r / D is shown. It is.

As shown in FIG. 15, as the nozzle inclination angle θ approaches 90 degrees from zero, the heat transfer coefficient increases and the cooling performance is improved. This is because the flow rate at which the cooling fluid reaches the position increases.
Therefore, if the correction according to the nozzle inclination angle θ is performed, the temperature simulation of the first embodiment or the accuracy of determining the cooling condition of the second embodiment can be improved.
Other configurations and operational effects are the same as those in the first embodiment.

The graph which shows the relationship between Reynolds number Re and a heat transfer coefficient in Example 1 others. The graph which shows the change of the heat transfer coefficient with respect to the distance r / D from the water flow center in Example 1 and others. The graph which shows the result of having changed the temperature of the forging die at the time of the cooling start in Example 1, and estimating the temperature of the forging die after the start of cooling. 3 is a graph showing the relationship between the Reynolds number Re and the heat transfer coefficient in Example 1. Explanatory drawing explaining the verification experiment which cools a to-be-cooled body in Example 1. FIG. The graph which compares the actual measurement value and calculation value in the verification experiment which cools the to-be-cooled body in Example 1. FIG. The graph which shows the change of the ultimate flow volume with respect to distance r / D from the water flow center in Example 3. FIG. The graph which shows the change of the heat transfer coefficient with respect to the distance r / D from the water flow center in Example 3. FIG. The graph which shows the temperature change of the forging die which performs hot forging in Example 4. FIG. The graph which shows the temperature change in 1 period of the forging die which performs hot forging in Example 4. FIG. Explanatory drawing explaining R / D showing the breadth of the cooling fluid supplied from a nozzle in Example 5. FIG. The graph which shows the relationship between the spreading degree R / D of the cooling fluid in Example 5, and the heat transfer coefficient of a water flow center. The graph which shows the change of the heat transfer coefficient with respect to distance r / D from the water flow center in Example 5. FIG. Explanatory drawing explaining nozzle inclination angle (theta) in Example 6. FIG. The graph which shows the influence which the nozzle inclination angle (theta) in Example 6 has on the change of a heat transfer coefficient.

Explanation of symbols

10 Cooled object, forging die 101 Circular end face 102 Axis 20 Nozzle

Claims (11)

In the temperature simulation method for estimating the temperature distribution when the object to be cooled is cooled by the cooling fluid supplied from the nozzle,
A Reynolds number calculating step of calculating the Reynolds number of the cooling fluid flowing in the nozzle;
An hc distribution calculating step of calculating an hc distribution that is a distribution of a heat transfer coefficient with the cooling fluid on the outer surface of the cooled object, based on the Reynolds number;
And a temperature distribution calculating step of obtaining a temperature distribution of the inside and outside surfaces of the object to be cooled based on the hc distribution.   2. The temperature simulation method according to claim 1, wherein the object to be cooled is a forging die for forging press molding.   In Claim 1 or 2, in the hc distribution calculation step, a first map representing a relationship between the Reynolds number and the heat transfer coefficient at the water flow center of the nozzle on the outer surface of the cooled body; A temperature simulation method for obtaining the hc distribution using a second map representing a relationship between a distance from the water flow center and a heat transfer coefficient ratio that is a ratio of the heat flow coefficient at the water flow center. .   4. The temperature simulation method according to claim 3, wherein the first map and the second map are corrected using an index representing a degree of spread of the cooling fluid supplied from the nozzle.   5. The temperature simulation method according to claim 3, wherein the second map is corrected by a curvature of the outer surface of the cooled object. In the method for determining the cooling conditions when cooling the object to be cooled by the cooling fluid supplied from the nozzle,
A target setting step for setting a specific point in the body to be cooled and setting a target temperature that is a temperature of the specific point after a predetermined time;
An hc distribution determination step for determining an hc distribution, which is a distribution of a heat transfer coefficient between the cooling fluid and the cooling fluid on the outer surface of the object to be cooled necessary to achieve the target temperature;
A Reynolds number determining step for determining a Reynolds number of the cooling fluid flowing in the nozzle based on the hc distribution;
Based on the Reynolds number, at least one of the nozzle inner diameter, the flow rate of the cooling fluid in the nozzle, the flow rate, the temperature, the kinematic viscosity coefficient, and the cooling condition defined by the type of the cooling fluid is determined. And a specification determining step for determining the cooling condition.   The cooling condition determination method according to claim 6, wherein the object to be cooled is a forging die for forging.   In Claim 7, in the Reynolds number determination step, the first map representing the relationship between the Reynolds number and the heat transfer coefficient at the water flow center of the nozzle on the outer surface of the cooled object, and the water flow A method for determining a cooling condition, wherein the Reynolds number is obtained using a second map representing a relationship between a distance from the center and a heat transfer coefficient ratio that is a ratio to the heat transfer coefficient at the water flow center. .   9. The cooling condition determination method according to claim 8, wherein the first map and the second map are corrected using an index representing a degree of spread of the cooling fluid supplied from the nozzle. .   10. The cooling condition determination method according to claim 8, wherein the second map is corrected by the curvature of the outer surface of the object to be cooled.   The second map according to any one of claims 8 to 10, wherein the second map is an angle formed by a normal direction of an outer surface of the body to be cooled and a nozzle direction in which the nozzle blows the cooling fluid. A method for determining a cooling condition, which is corrected by a certain nozzle inclination angle.

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