JPS61192520A - Manufacture of powder sintering product - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing powder sintered products such as ceramics and sintered alloys.

(Prior art) Generally, when producing fine ceramic products and sintered metal products such as sintered tungsten carbide tools, raw material powder is compression-molded using a mold to obtain a molded product, and this molded product is sintered. If you try to make a product out of it, it is difficult to accurately determine the amount of shrinkage during sintering, so you have to modify the mold shape many times, which increases time and cost. In addition, in the case of high-mix, low-volume production, it is not appropriate to prepare a mold all by itself because it increases costs.

Therefore, in the past, raw material powder was formed into a simple shape using a mold, etc., and then sintered, and the resulting sintered product was subjected to grinding or electrical discharge machining.
The product is manufactured through mechanical processing.

(Problems to be Solved by the Invention) However, according to the above method, grinding is not an economical method because there are restrictions on the shape to be processed, the processing speed is slow, and the grindstone is often consumed. Furthermore, electrical discharge machining is limited to materials that are conductive, and the machining speed is slow, making it unsuitable for mass production.

Therefore, the inventors conducted repeated research into methods for obtaining high-precision products without long-term machining after sintering, and found that they could produce molded products of raw material powder or semi-sintered products by semi-sintering this molded product. We discovered that ultrasonic processing can be performed with high efficiency. According to this ultrasonic processing, for example, a cold compression molded product of alumina powder can be processed at a frequency of 18 KHz, a maximum imaging width of 30 μ, and a pressing force of 200 using an ultrasonic vibration tool (diameter 3 am + 7).
With ultrasonic processing under these conditions, a depth of 10# can be achieved in about 10 seconds without using water or abrasive grains! I was able to make a hole for II. In addition, the above molded product was heated to an alumina sintering temperature of 1800.
Regarding semi-sintered products that are semi-sintered at 1200℃ relative to ℃,
When machining was carried out under the same conditions as above, a hole with a depth of 10M could be drilled in a sufficiently short time of about 20 seconds. On the other hand, when the above sintered product is sintered at 1800°C and subjected to ultrasonic processing under the same conditions, the depth is 10II11.
It takes a long time, approximately 240 minutes, to drill a hole.

This invention was completed by the inventors after further research based on the above knowledge, and by applying ultrasonic processing before sintering, it is possible to avoid long-term mechanical processing after sintering. The present invention aims to provide a method for producing a powder sintered product that can economically produce a sintered product with desired precision.

1. l (Means for solving the problem) However, the first invention of this application involves processing a predetermined portion of a sample made of a powder molded product or a semi-sintered product of the molded product into a predetermined size by ultrasonic machining, and This is a method for producing a powder sintered product, which is characterized by sintering a processed product. Further, the second invention of this application is to process a predetermined portion of a sample made of a powder molded product or a semi-sintered product obtained by semi-sintering the molded product into a predetermined size by ultrasonic machining, and then process this processed product into a predetermined size using a sintering machine. Measure the dimensions of the part, calculate the dimensional difference between this measured value and the target dimension of the sintered product, correct the above set dimensions according to this dimensional difference and the linear shrinkage rate due to sintering of the above sample, and create a new one. Ultrasonic processing using the corrected set dimensions for the sample, dimensional measurement after sintering, and calculation of the dimensional difference are repeated until the dimensional difference is within the allowable dimensional difference of the sintered product, and from then on, the final set dimensions are This is a method for manufacturing a powder sintered product, which is characterized in that a sample is subjected to ultrasonic processing based on the method and then sintered. Further, the third invention of this application is to process a predetermined portion of a sample made of a powder molded product or a semi-sintered product obtained by semi-sintering the molded product into a predetermined size by ultrasonic machining, and then sinter it to meet the final allowable size. This is a method for producing a powder sintered product, which is characterized in that a sintered product having a finishing allowance is obtained, and the sintered product is finished by ultrasonic machining.

In the present invention, the powder molded product is preferably formed by compression molding using a metal mold, but may be formed by casting or other molding methods.

Semi-sintering in this invention refers to sintering at a temperature below the sintering (main sintering) temperature to obtain a sintered product (final product), and the molded product has the property of being easily broken during ultrasonic processing. The semi-sintering temperature is selected as appropriate depending on the individual material. For example, in the case of alumina whose sintering temperature is 1800°C, 800°C to 120°C
Semi-sintering at about 0'C reduces deformation during ultrasonic processing and reduces processing time during ultrasonic processing.

Although the ultrasonic machining in this invention can be performed without supplying water between the vibrating tool and the workpiece, supplying water as described above has the effect of preventing the generation of dust and improving the machining speed. Furthermore, if abrasive grains are suspended in water as described above, the processing speed can be greatly improved.

In addition, it is preferable to use distilled water as the above-mentioned water because it prevents problems such as chlorine in tap water reacting with alumina and remaining in the sintered body as aluminum chloride when sintering alumina. . Further, as a vibrating tool for ultrasonic machining, in addition to a normal metal vibrating tool, a vibrating tool having diamond abrasive grains or the like fixed to the outer periphery can also be used.

In addition, the linear shrinkage rate in this invention is the linear shrinkage rate when a molded product or semi-sintered product is sintered, and it varies depending on the material of the molded product. Since the values may vary, it is best to use values appropriate for each part to be machined. If the linear shrinkage rate γ is unknown, an actual sample can be sintered and an accurate value corresponding to the actual product can be easily determined using the following equation.

γ = Shrinkage amount due to sintering / Dimension before sintering For example, if a hole with a diameter of 3.2 m is made in a molded product and the diameter of the hole in this sintered product becomes 2.9 tax, γ - (3
,2-2,9)/3.2-0.094.

The content of this invention will be described below in the first embodiment corresponding to the embodiment of the second invention.
To explain with reference to Fig. 2 and Fig. 2, sample A, which is a powder molded product or its semi-sintered product, is sintered with a target dimension of Lo and an allowable dimensional difference of ±1 in a predetermined part (for example, the inner diameter of a square hole). When manufacturing product B (see Figure 2 (a)), first set the machining dimensions for the first sample. It is preferable to use the following values because the dimensional difference in the sintered product is small. However, γ is the linear shrinkage rate due to sintering of the sample.

L=Lo(1+γ) ・・・・・・(1) Next, the sample was subjected to ultrasonic processing according to these set dimensions, and as shown in Fig. 2(b)
The processed product shown in FIG. 1 is sintered to obtain a sintered product C shown in FIG. Next, add this measurement value x 1 to the target size. The difference is calculated using the following formula.

ΔX −Lo−Xl −−−−−−(2) However, if ΔX1 is a negative value, it will be treated as a negative number instead of an absolute value hereinafter. Next, the dimensional difference ΔX1 and the allowable dimensional difference ±
ρ is compared, and if ΔX1 is outside the range of ±1, the L dimension is corrected to the following two dimensions according to this ΔX1 and the linear shrinkage rate γ.

L = L - ΔX1 (1 + γ) (3
) Next, perform ultrasonic processing on a new sample with these 12 dimensions as shown in Figure 2 (d), and sinter it to obtain the dimension X.
, calculate the dimensional difference x 2, compare it with the allowable dimensional difference ±1, and correct the set dimensions in the same way as above. The set dimensions for the first sample are expressed by the following equation.

L・=1=−AXH−1(1+7)・(4) When the dimensional difference ΔX is within the range of ±1, fix the set dimension and then try again using this final set dimension. By ultrasonically processing the material and sintering the workpiece, a sintered product that is within desired tolerances can be obtained.

In the above description, the allowable dimensional difference of the sintered product is ±ρ, but this allowable dimensional difference is -1, +J.

Similarly, when the positive and negative sides are different, when one side is O, or when both are positive or negative numbers, the dimensional difference Δ
All you have to do is compare it with X. Furthermore, the embodiments of the present invention also include cases where the measured value Xi and the target dimension (for example, thρ) are directly compared, and the dimensional difference ΔX1 and the allowable dimensional difference (for example, ±1) are indirectly compared. shall be taken as a thing. Further, the correction term ΔX(1+γ) for the set size can be multiplied by an appropriate constant determined through experiments depending on the material, shape, etc. of the molded product.

In addition, in the third invention, the X dimension (for example, X) after sintering in FIG.
), set the setting machining method
The iq sintered product C is finished by ultrasonic processing to obtain a sintered product B. In addition, if the processing dimensions are external dimensions,
The set machining dimensions may be determined so that the X dimension after sintering is larger than the final allowable dimension (Lo+J).

(Function) In this way, the ultrasonic processing before sintering is performed on a semi-sintered product obtained by semi-sintering the molded product b+, which is easy to process. In addition, in the second invention, since the set dimensions are cumulatively corrected using the dimensional difference between the measured dimension and the target dimension of the sintered product and the linear shrinkage rate as factors, it is more suitable for processing and sintering trials for several samples. Accurate final set dimensions can be obtained. Also the third
In the invention, processing can be performed before sintering so that the sintered product has dimensions that leave a finishing allowance for the raw material, so finishing processing after sintering can be performed in a short time.

(Example) The present invention will be described in detail below.

FIG. 3 shows a numerically controlled ultrasonic machining device M1 used in the method of the present invention, 2 is an ultrasonic machining head, a magnetostrictive transducer 4 connected to a high frequency oscillator 3, a cone-shaped horn 5 and an exponent. It has a known structure in which a shell-shaped horn 6 is combined and fixed to a water-cooled container 7 with a flange 8. A measuring tool 10 consisting of a vibrating tool 9 and a touch sensor is detachably attached to the tip of the exponential horn 6 by a tool changer 11. The entire ultrasonic machining head 2 is guided by a guide frame (not shown) to be able to move up and down, and is driven up and down via a spindle 12 by a hydraulic cylinder 13 (which may be an electric linear actuator). 14 is 2 for detecting displacement in the vertical (Z-axis) direction of the ultrasonic processing head 2;
It is an axis scale. On the other hand, 15 is a CNC control device that drives the X-axis drive motor 18 and the Y-axis drive motor 19 by inputting from the paper key 716 or the keyboard 17.
It drives the cross table 20, drives the hydraulic cylinder 13, moves the ultrasonic machining head 2 up and down, and also gives commands to the high frequency oscillator 3 and tool changer 11, thereby performing program control of the entire device. 21 and 22 are XY cross table position detectors. In addition, the CNC control device 15 includes a memory for storing the measured dimensions of the sample to be processed, the target dimensions of the sintered product, dimensional tolerances, etc., and the calculations expressed by the above-mentioned equations (1) to (4). It has a built-in arithmetic device, etc.

According to the numerically controlled ultrasonic machining device 1 having the above configuration, in addition to drilling a recess corresponding to the external shape of the tool by raising and lowering the vibrating tool 9, the width of the recess is drilled by driving the XY cross table 20. The dimensions can be changed freely, and the fourth
As shown in the figure, automatic enlargement processing can be performed while moving the moving tool 9 in a circular motion relative to the workpiece, or processing can be performed while moving the vibrating tool 9 in a spiral pattern as shown in FIG. Furthermore, instead of these circular movements, polygonal movements can be made to perform polygonal drilling. Furthermore, as shown in FIG. 6, a workpiece can be contoured into a desired profile shape using a rod-shaped vibrating tool 9 having diamond abrasive grains fixed to its outer periphery.

To perform processing using the apparatus configured as described above, a powder molded product or a sample obtained by semi-sintering the molded product is mounted on the XY cross table 20, and a predetermined vibrating tool 9 is connected to an exponential horn using the tool conversion device 11. Attach it to 6,
A sample is subjected to ultrasonic processing according to the set dimensions expressed by the above equation (1). Although the opening ceremony and FIGS. 1 and 2 show one-dimensional dimensions, if there are target dimensions in each two-dimensional or three-dimensional dimension, ultrasonic processing is performed in each direction according to each set dimension. Next, the processed product after ultrasonic processing is sintered, the sintered product is set on the XY cross table 20, and the measuring tool 10 is attached to the exponential horn 6 using the tool changer 11. Measure the dimension of the part corresponding to the above set dimension x 1 (in the case of multidimensional dimensions, dimensions in each direction. Calculations and corrections below: same as b). This measurement is performed by applying the measuring end of the measuring tool 10 to one measuring surface of the sintered product with a predetermined measuring pressure under the command of the CNC control device 15.
Drive the cross table 20 or the hydraulic cylinder 13 to apply the measurement end to the other measurement surface, and
Moving distance 1i1 of stable 20 or spindle 12
1t (If horizontal, add the diameter of the measuring end)
This is done by calculating within the CNC control device 15 from . This measured value x 1 and the target size stored in the memory in the CNC control device 15. The arithmetic unit in the control device 15 calculates equation (2) using The same ultrasonic processing, sintering, measurement, calculation, etc. as described above are performed on a new sample according to the set dimension L2, and the same steps are repeated thereafter. When the dimensional difference △X falls within the allowable dimensional difference ±1, the final set dimension at that time is stored in the memory in the CNC control device 15, and from then on all samples are subjected to ultrasonic processing using this set dimension. All you have to do is sinter it. Even during mass production based on the final set dimensions, it is desirable to timely sample the sintered product, measure the dimension X, compare it with the target dimension, and correct the set dimensions as necessary.

Next, an example of the third invention using the apparatus having the above configuration will be described. Width 20fnIR1 Length 50#ll11. Thickness 20m+
In order to obtain a sintered alumina product in which a regular hexagonal hole with a negative side length of 4±0.02 am+ and a depth of 7 m is bored in the thickness direction in a block body, first, the alumina is The raw material powder was compression molded using a mold and then semi-sintered at 1200°C. Attach this semi-sintered product to the XY cross table 2o, and -
Using a regular hexagonal vibrating tool 9 with a side length of 3.90 m+, a hexagonal hole with a side length of 4.2 m was bored in the above sintered product by giving an NC offset to the tool using a CNC control device 15. The processing time required to drill a hexagonal hole with a depth of 7 m is 5
It was a minute. The order of processing dimensions 4.2 is based on the above formula (1) using the known linear shrinkage rate γ-0.05 when sintering a semi-sintered alumina product. This is the machining dimension L1 obtained for -4 shoes. Next, the above processed semi-sintered product is 180mm
When sintered at 0℃, the dimensions of each side of the hexagonal hole were 3.9 to 3.
．． It became 96m+. Therefore, this sintered product was subjected to ultrasonic processing using the numerically controlled ultrasonic processing device 1 with the vibrating tool 9 given an offset of 0.07 am in the side direction of the hexagon. A final product with square holes was obtained. The time required for this finishing process was 5 minutes.

In addition, during each of the above ultrasonic processing, ultrasonic processing of semi-sintered products is performed in a dry state without supplying processing liquid such as water between the vibrating tool and the workpiece, and during finishing processing after sintering, the ultrasonic processing of semi-sintered products is carried out in a dry state.
A suspension of No. 0 green carborundum in water was used as the processing liquid. In addition, when the alumina raw material powder was compressed and sintered at 1800°C without being processed as in the conventional method, a hexagonal hole was drilled using the vibrating tool 9. Even with the processing fluid described above, the processing time was More than 5 hours,
It took an extremely long time.

The present invention is not limited to the above-mentioned embodiments; for example, dimensions may be measured manually, or a vibration tool 9 may be used.
The present invention can also be implemented using an apparatus other than the numerically controlled ultrasonic processing apparatus 1, such as by manually replacing the apparatus. Further, the ultrasonic machining head 2 can also be used by being incorporated into a machining center.

Further, as shown in FIGS. 6 and 7, one end of a vibrating rod 31 with diamond abrasive grains 30 fixed to the outer periphery of the rod is
It is fixed to a ball 33 rotatably attached to the arm 32,
The other end of the vibrating rod 31 is slidably inserted in the longitudinal direction into a ball 35 rotatably attached to the arm 34, and the third
An ultrasonic vibrating device 36 consisting of a magnetostrictive vibrator 4, a cone-shaped horn 5, and an exponential-shaped horn 6 similar to the device shown in the figure.
The tip 37 and the ball 33 are connected to each other by wire A73 for vibration transmission.
8, and the arm 34 is connected to the U-axis drive motor 39 and the V
If an ultrasonic machining device 41 is driven in a two-dimensional direction by a shaft drive motor 40 and is equipped with an XY-O stable 20 similar to the device described above, the processed surface of the sample 42 before sintering can be a straight line. Various linear surfaces such as conical surfaces, hyperbolic paraboloids, and spiral surfaces can be obtained as surface elements, and sintered turbine blades and the like can be manufactured.

(Effects of the Invention) As explained above, according to the present invention, since ultrasonic processing is performed in an easy-to-process state before sintering, the processing time is short, and it is possible to process non-conductive materials and various shapes. Provided is a method for manufacturing a useful powder sintered product that can be widely applied to various objects. Further, according to the second invention, non-uniform shrinkage of each part due to sintering can be corrected by several trials of machining and sintering, and appropriate machining dimensions can be set, allowing sintering with desired dimensional accuracy. It is possible to economically produce products in a short time. Furthermore, according to the third aspect of the invention, since finishing processing is performed by ultrasonic processing, a sintered product with high dimensional accuracy can be manufactured economically in a short time.

[Brief explanation of the drawing]

1 to 6 show an embodiment of the present invention.
The figure is a flowchart showing the process, Figure 2 (a) to ('')
is an explanatory diagram of the dimensional relationship, Fig. 3 is a diagram of the equipment configuration of the equipment used, and Figs. 4 to 6 are the motion states of the vibrating tool ffi! An explanatory diagram, FIG. 7 is a device configuration diagram showing another embodiment of the device used, and FIG. 8 is a longitudinal cross-sectional view of the main part. DESCRIPTION OF SYMBOLS 1... Numerical control ultrasonic processing device, 2... Ultrasonic processing head, 9... Vibration tool, 10... Measuring tool, 11
... Tool changer, 13... Hydraulic cylinder, 15.
・・ONC! II m device, 18... X-axis drive motor, 19... Y @ drive motor, 20...
38...Wire, 39...U-axis drive motor, 40...
・・V-axis drive motor, 41 ・・Ultrasonic processing device.

Claims (1)

[Claims] 1. Processing a predetermined portion of a sample made of a powder molded product or a semi-sintered product of the molded product into a set size by ultrasonic processing,
A method for producing a powder sintered product, which comprises sintering this processed product. 2 A predetermined portion of a sample consisting of a powder molded product or a semi-sintered product obtained by semi-sintering the molded product is processed to a set dimension by ultrasonic machining, and after sintering this processed product, the dimensions of the above predetermined portion are measured; Calculate the dimensional difference between the measured value and the target dimension of the sintered product, correct the above set dimensions according to this dimensional difference and the linear shrinkage rate due to sintering of the above sample, and make the corrected settings for the new sample. Ultrasonic processing based on dimensions, dimensional measurement after sintering, and calculation of dimensional difference are repeated until the dimensional difference falls within the allowable dimensional difference of the sintered product. From then on, the sample is subjected to ultrasonic processing based on the final set dimensions. A method for producing a powder sintered product, characterized in that the product is sintered after sintering. 3 A sintered product that has a finishing allowance with respect to the final allowable dimension by processing a predetermined part of a sample consisting of a powder molded product or a semi-sintered product obtained by semi-sintering the molded product to a set dimension by ultrasonic processing, and then sintering it. 1. A method for producing a powder sintered product, comprising: obtaining the sintered product, and finishing the sintered product by ultrasonic processing.