JPH10317011A - Heat treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently enable heat-treating of a material to be heat-treated while restraining uneven deformation. SOLUTION: This heat treatment apparatus is provided with an atmosphere heating furnace 1 for heat-treating the material 2 to be heat-treated, a camera 6 for monitoring the material 2 to be heat-treated from the outside through a peep hole 7 in the atmosphere heating furnace 1 and a picture data analyzing device 8 for analyzing the shape, deforming quantities, distribution of the deforming quantities and uneven deformation of the material 2 to be heat-treated during the heat treatment based on the output of picture data monitored with the camera 6. Atmosphere heating temp. is controlled with heaters 3 through a temp. controller 9 so as to restrain the uneven deformation of the material 2 to be heat-treated to the min. limit according to analyzed result with the picture data analyzing device 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for heat-treating an object to be heat-treated while suppressing its non-uniform deformation.

[0002]

2. Description of the Related Art In a metal powder injection molding method (MIM), a metal powder and an organic binder, a plasticizer and a lubricant as a binder are heated and kneaded, and injection-molded into a mold having a desired shape. Debindering and sintering are performed. Further, this metal powder injection molding method is a technology capable of economically mass-producing a high-performance metal part having a complicated shape, and its greatest feature is that a three-dimensional complicated shape product can be manufactured with high precision.

However, the shape of a product currently manufactured by this method is not so complicated, and it is hard to say that the advantages of the present technology are sufficiently exhibited. The biggest factor that makes it difficult to manufacture products having complicated shapes is uneven deformation during degreasing and sintering. In particular, in the sintering step, the volume shrinkage is as large as about 40 vol%, and the more the shape is three-dimensional and complicated, the more likely non-uniform deformation occurs.

[0004] Even if uneven deformation occurs, straightening or sizing after sintering is not easy due to the complexity of the shape, which is a factor that raises the cost. For these reasons, there is an urgent need to establish a technology to prevent uneven deformation during sintering of products by this method.
It is necessary to know the nature of the uneven deformation.

On the other hand, a dilatometer has been conventionally used for measuring a dimensional change during heat treatment.
This is a magazine, Ceramics vol. 23 no. 11
As shown in PP1082-1087, a sample having a diameter of 3 to 10 mm is put in a silica glass tube whose one end is sealed and the other end is opened, and this is lightly pressed with a silica glass rod.

[0006] These are heated and cooled in an electric furnace, and the displacement of the push rod is measured using a dial gauge or the like to measure the shape and the amount of deformation.

At this time, There has also been proposed a method in which a standard sample of the same length is pressed into a silica glass tube with another silica glass rod so that the deformation state of the standard sample and the sample can be determined from the shape and the amount of deformation of the sample.

Further, there is provided a thermal dilatometer for optically non-contact measurement of the shape of an object to be heat-treated without using the silica glass tube or the silica glass rod and performing a heat treatment as high as the heating furnace permits. It is connected.

[0009]

However, in such a conventional shape measuring method using a dilatometer, generally only a one-dimensional dimensional change of an object having a simple shape can be measured, and non-uniformity during the heat treatment of a product having a complicated shape is generally measured. There was a problem that the deformation could not be measured. On the other hand, the non-contact type optical measuring device is basically limited to one-dimensional measurement of the position of a mark attached to the surface of the object to be measured, similarly to the measurement with a push bar type dilatometer, and therefore, is complicated. The problem of non-uniform deformation accompanying the heat treatment of the shaped article is that after the treatment is completed, the only method is to measure and confirm the dimensions of each part of the workpiece at room temperature.

Further, it is not possible to determine at what time during the processing the non-uniform deformation occurs during the heat treatment and for what cause, and the condition search for suppressing the non-uniform deformation requires trial and error. The current situation is repeating.

[0011] On the other hand, in the sintering of the object to be heat-treated, it is considered that a smaller heating rate is more advantageous for suppressing non-uniform deformation than a larger one. For example, as shown in FIG. It has been confirmed that the non-uniform deformation index decreases as the temperature decreases, whereas the non-uniform deformation index increases as the heating rate increases.

However, if the rate of temperature rise is to be reduced to suppress non-uniform deformation, there has been a problem that the operating efficiency of the atmosphere heating furnace deteriorates.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and measures non-uniform deformation during heat treatment, which is impossible with conventional dilameters or optical / non-contact one-dimensional measurement of a heat-treated object. It is an object of the present invention to provide a heat treatment apparatus that enables the heat treatment of an object to be heat treated efficiently while suppressing uneven deformation according to the measurement result.

[0014]

To achieve the above object,
2. A heat treatment apparatus according to claim 1, wherein the heat treatment apparatus heat-treats the heat treatment object installed therein while controlling the atmosphere heating temperature, and a camera which externally monitors the heat treatment object through a window of the atmosphere heat furnace. And an image data analyzer for analyzing the shape, deformation amount, distribution of deformation amount and non-uniform deformation of the object to be heat-treated during heat treatment based on the output of image data monitored by the camera. According to an analysis result by the analysis device, a temperature controller controls the atmosphere heating temperature by a heater so as to minimize non-uniform deformation of the object to be heat-treated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an atmosphere heating furnace, 2 denotes an object to be heat-treated in the atmosphere heating furnace 1, and 3 denotes a heater installed in the upper and lower portions of the atmosphere heating furnace 1 so as to sandwich the object to be heat-treated 2. It is.

Reference numeral 4 denotes an illuminating device for irradiating light from the outside to the heat treatment object 2 inside through the window 5 of the atmosphere heating furnace 1. Reference numeral 6 denotes a camera for externally monitoring the object 2 to be heat-treated through another window 7, and reference numeral 8 denotes a processor for processing and analyzing image data from the monitored camera 6.
The shape, deformation, distribution of deformation,
This is an image data analyzer that performs measurement of non-uniform deformation.

Further, 9 is to minimize the non-uniform deformation of the object to be heat-treated based on the analysis data of the shape, the amount of deformation, the distribution of the amount of deformation and the non-uniform deformation of the object to be heat-treated 2 obtained by analyzing image data. A temperature controller 10 that outputs temperature control data for limiting the temperature to a minimum is a transformer for adjusting the power supplied to the heater 3 based on the temperature control data from the temperature controller 9.

The optical system connecting the illuminating device 4 and the camera 6 may be provided with an optical mirror, a lens, an optical filter, and the like, if necessary, and prevents an error from occurring due to vibration. Therefore, it is optional to install the entire apparatus on a vibration isolation table.

The atmosphere heating furnace 1 is necessary to prevent the formation of oxide scale on the surface of the workpiece 2 at a high temperature, so that the accuracy in specifying the same object point can be secured. The internal structure such as the heater of the atmosphere heating furnace 1 is as follows.
The surface heat treatment product 2 should be designed and processed so that it can be illuminated and monitored from outside.

Further, when a sample containing a binder or the like is subjected to a heat treatment such as sintering, the glass of the windows 5 and 7 is fogged by volatile substances, so that illumination and observation of the sample may be impossible. In order to prevent this, a shutter that can be opened and closed from the outside may be attached inside the windows 5 and 7.

In the heat treatment apparatus, the object to be heat treated 2
Is constantly monitored by the camera 6, and the obtained image data is analyzed by the image data analyzer. The shape and amount of deformation of the object to be heat-treated 2 and the distribution and non-uniform deformation of the amount of deformation can be recognized by comparing the image data of the measurement object, which changes with time, with reference image data serving as a reference.

The data of the shape, the amount of deformation, the distribution of the amount of deformation and the non-uniform deformation of the object to be heat-treated 2 analyzed by the image data analyzer are taken into a temperature controller 9. And output temperature control data for minimizing non-uniform deformation of the heat treatment target 2.

The temperature control data is basically stored in the transformer 1
This is control data of the amount of power supplied to 0 or control data for performing tap switching of the transformer 10. As a result, if the non-uniform deformation is too large,
In the case where the power supplied to the heater 3 is suppressed and the non-uniform deformation is small, the power supplied to the heater 3 can be increased to increase the heat treatment speed (efficiency).

Here, in order to accurately specify a point on the surface of the object between the image data of the object to be measured and the reference, it is necessary that a strong correlation exists between the reference image and the image of the object to be measured. It is. That is, it is premised that even if the deformation of the surface heat-treated product 2 due to the heat treatment progresses, the luminance distribution of the minute region around the point to be measured on the sample surface does not largely collapse between the two images.

However, during the heat treatment, the surface condition of the heat treatment target 2 changes. In addition, as the temperature increases, the heat treatment target 2 and the furnace materials such as the heater 3 emit light spontaneously, and the heat treatment target 2 The state of reflection of light on the surface also changes.

Therefore, it is sometimes difficult to directly correlate the image of the workpiece 2 at room temperature with the image being heat-treated at a high temperature. In this case, as shown in FIG. The image must always be reset to an image in a temperature range where the correlation is strong.

That is, according to the present invention, when the correlation between the reference image and the image to be measured deteriorates, the reference image is successively reset to the high temperature side, that is, in FIG. 2, the image is set as image → image → image → image. Then, the final displacement can be calculated by adding the increment of the displacement amount every time the reference image is switched.

Next, it is necessary to specify the same object point by image data analysis in such a way that a large number of measurement points individually refer to an appropriate reference image, and individually and in parallel for each measurement point at which the reference image is switched. Will be described.

To quantify the amount of non-uniform deformation of the object 2 during heat treatment, a large number of measurement points are required on the surface of the object 2; however, all the measurement points refer to the same reference image. If the number of measurement points increases, the probability of having to switch the reference image increases when the number of measurement points increases, and the number of times the reference image is switched inevitably increases when the number of measurement points increases. .

On the other hand, the calculation of the displacement amount by specifying the same object point using two images always includes a slight error to be avoided. In the present invention, when the correlation between the reference image and the image to be measured deteriorates, the reference image is successively reset to the high temperature side,
Since the final displacement is calculated by adding the increment of the displacement for each reference image switching, as shown in FIG. 3, there is a limit that the measurement accuracy of the displacement amount deteriorates as the number of switching of the reference image increases. .

Therefore, in order to overcome this limitation, the method in which all measurement points refer to one reference image (hereinafter referred to as specifying method 1) has been revised so that each measurement point can individually refer to the reference image. In addition, a method of individually switching the reference image (hereinafter, specified method 2) has been developed to measure non-uniform deformation during heat treatment.

As a result, each measurement point can refer to a unique appropriate different reference image as required, so that the individual measurement points are not affected by the change of the reference image at the other measurement points. Measurement accuracy.

In this method, only the luminance distribution of a small area (usually about 100 pixels) cut out from an image is resident in the memory of the image data analyzer 8 at each measurement point as shown in FIG. Switching is performed as a reference image, and the entire image (usually 250,000 pixels or more) can be executed with less memory than when the entire image is resident in the memory as a reference image.

FIG. 5 shows a comparison result of the reference image switching number in the deformation amount measurement during the heat treatment (solution treatment) of the stainless steel of the above-mentioned specific method 1 and the specific method 2. When the identification method 2 is used, the number of times of switching is 40% or less of the identification method 1, and the accuracy is greatly improved. When three-dimensional shape measurement is required, two monitor cameras are installed to obtain the two-dimensional shape.
Three-dimensional spatial coordinates can also be calculated from the two images.

FIGS. 6 and 7 show a green 11 molded by a metal powder injection molding method. FIG. 8 shows a sintering process of the green 11 in an atmosphere heating furnace 1.
1 shows temperature versus shape change characteristics obtained by two-dimensionally measuring the non-uniform deformation of No. 1.

Here, the sintering shrinkage can be determined by the height C of the green 11, and the non-uniform deformation can be determined by the ratio of each width B and A at the upper end and the lower end of the green 11.

Therefore, this green 11 has a sintering shrinkage of 1
It can be seen that the deformation starts at about 000 ° C., the non-uniform deformation starts immediately after that, shows a peak in the middle, and finally ends in the deformation in the opposite direction to the start.

In the case K1 of FIG. 8 in which the measurement result of the non-uniform deformation is not fed back to the temperature controller 9, a large non-uniform change occurs, but the measurement result is transmitted to the temperature controller 9. In case K2 of FIG. 8 in which the feedback is reflected on the heating pattern (temperature control data), it was confirmed that the non-uniform deformation was suppressed to a small degree even in a region of 1000 ° C. or higher.

As described above, in the present invention, the non-uniform deformation of the heat treatment target 2 is controlled by controlling the temperature of the heat treatment in accordance with the degree of the measured non-uniform deformation of the heat treatment target 2 such as green. The effect is obtained that the efficiency of the heat treatment operation can be greatly improved while suppressing.

In the above embodiment, the heat treatment target 2
Has been described, but the same effect can be obtained in a plurality of cases. Then, once the optimum temperature pattern and the optimum heating output pattern of the heat treatment are grasped, a similar heating target 2 is realized, and thereafter, a heating control furnace is realized without repeating the above-described measurement. it can.

[0041]

As described above, according to the present invention, an atmosphere heating furnace for heat-treating an object to be heat-treated therein while controlling the atmosphere heating temperature, and the object to be heat-treated through a window of the atmosphere heating furnace. A camera that is externally monitored, and an image data analyzer that analyzes the shape, the amount of deformation, the distribution of the amount of deformation, and the non-uniform deformation of the object to be heat-treated during the heat treatment based on the output of the image data monitored by the camera. According to the result of the analysis by the image data analyzer, the temperature controller is configured to control the atmosphere heating temperature by a heater so as to minimize the non-uniform deformation of the object to be heat-treated. And one-dimensional measurement of the object to be heat-treated by optical and non-contact methods makes it possible to measure non-uniform deformation during heat treatment, which is considered impossible. According to the results, if the non-uniform deformation is within the allowable range, raise the heat treatment temperature to pursue the heat treatment operation efficiency, while if the non-uniform deformation is expanding beyond the allowable range, lower the heat treatment temperature. Thus, an effect is obtained that the object to be heat-treated can be efficiently heat-treated while suppressing the non-uniform deformation.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a heat treatment apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a procedure for specifying a measurement point on a heat treatment object, which is performed in a shape measurement method of the heat treatment object according to another embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a reference image switching frequency and a measurement error according to the shape measuring method of the present invention.

FIG. 4 is an explanatory diagram showing a method for identifying the same object point between a reference image and a measurement target image according to the present invention.

FIG. 5 is an explanatory diagram for comparing and displaying the number of times of reference image switching in the measurement of the amount of deformation during the heat treatment of stainless steel for two specific methods.

FIG. 6 is a front view showing a green formed by a metal powder injection molding method.

FIG. 7 is a side view of the green shown in FIG. 6;

FIG. 8 is an explanatory diagram showing non-uniform changes during the heat treatment of the green shown in FIG. 6;

FIG. 9 is a characteristic diagram showing a non-uniform deformation index of a heat-treated object with respect to a sintering temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Atmospheric heating furnace 2 Object to be heat-treated 3 Heater 5, 7 Window 6 Camera 8 Image data analyzer 9 Temperature controller

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yukitaka Mizuno 3-10-15, Yawatacho, Shinminato-shi, Toyama Pref. Japan Toyama Works (72) Inventor Ryuzo Watanabe Aoba, Sendai-shi 3-15-12, Taihara-ku, Tokyo (72) Inventor Ryo Kawasaki 5-51-701, Showa-cho, Aoba-ku, Sendai-shi

Claims (1)

[Claims] 1. An atmosphere heating furnace for heat-treating an object to be heat-treated therein while controlling an atmosphere heating temperature, a camera for externally monitoring the object to be heat-treated through a window of the atmosphere heating furnace, and a monitor for the camera. An image data analyzer for analyzing the shape, deformation amount, distribution of the deformation amount and non-uniform deformation of the object to be heat-treated during the heat treatment based on the output of the image data obtained in accordance with the analysis; A heat treatment apparatus comprising: a temperature controller that controls the atmosphere heating temperature by a heater so as to minimize non-uniform deformation of the heat treatment product.