JP4905896B2 - Packed particle bulk density determination apparatus and method - Google Patents

Description

The present invention relates to a packed particle bulk density determination apparatus and method for packed particles filled in a mold or a container.

In general, sintered metal parts used as automobile parts or the like are generally (1) filled with a certain volume of metal particles (for example, iron powder, aluminum powder, etc.) in a mold, and (2) pressed into the mold. It is formed into a desired shape, and (3) a sintered metal part is completed through a step of pressure firing.
The quality of the sintered metal part thus completed is greatly influenced by the “bulk density of the particle layer” when the mold is filled. Therefore, it is important to accurately measure the bulk density of filled particles in a state where the mold is filled.

  It is known that the “bulk density of the packed particles” is generally calculated with a precise measurement of the weight G and volume V of the packed particles and the ratio G / V, and the accuracy is high. However, it is very difficult to incorporate this means into the manufacturing process of the sintered metal part described above.

  Therefore, conventionally, in accordance with the “metal powder-apparent density test method” defined in JISZ2504, by injecting metal particles with their own weight into a fixed-capacity mold container, the excess amount is removed by scraping. An almost constant volume of metal particles was filled in the mold.

  In connection with the present invention, Patent Document 1 has been proposed as a means for measuring the apparent density (bulk density) of an irregular porous part.

  As schematically shown in FIG. 4, the means of Patent Document 1 includes (A) a liquid weight Gfl having a known density ρ in a container 52 up to a predetermined level S, and (B) a porous electrode plate 51 (measured). The weight Ga in the container that has reached the same level S in the state in which the object) has absorbed the liquid 53, and (C) the weight Gb of the electrode plate 51 in the state in which the liquid 53 has been absorbed are measured, and ΔG = Gfl−Ga + Gb The liquid weight corresponding to the volume V of the electrode plate is obtained, and the volume V of the electrode plate is obtained by V = ΔG / ρ. (D) The ratio Gc / V is obtained from the dry weight Gc of the electrode plate and the volume V of the electrode plate. The apparent density D is calculated.

Japanese Patent Laid-Open No. 6-349528, “Method and apparatus for determining physical parameters of storage battery electrode plate”

  As described above, it is very difficult to accurately measure the weight of only the filled particles filled in the mold in the manufacturing process of the sintered metal part.

Moreover, since the means of patent document 1 receives external forces, such as a hydraulic pressure, during measurement, it cannot be applied, after filling particle | grains are pressure-molded etc., etc. so that this external force may be endured. Therefore, there is a problem that a reduction in the yield of sintered metal parts cannot be prevented.
Furthermore, since the means of Patent Document 1 fills the pores of the object to be measured with a liquid, a post-process (drying or the like) for completely removing the liquid after measurement is necessary, and the liquid is filled and removed (drying). Etc.), the physical properties of the object to be measured may change.

On the other hand, in accordance with “Metal Powder-Apparent Density Test Method” defined in JIS, metal particles are injected by their own weight into a fixed-capacity mold container, and the excess amount is removed by scraping. The means for filling the metal particles into the mold is highly accurate and can be incorporated into the manufacturing process of the sintered metal part.
However, in the manufacturing process of sintered metal parts, if the metal particles are agglomerated due to aggregation or the like, the capacity filled in the mold may fluctuate greatly, and the accuracy may be greatly reduced.
In addition, with this means, the bulk density of the filler particles cannot be measured, so even if the bulk density fluctuates due to such lumps, the measurement can only be done after, for example, pressure forming, and the yield of sintered metal parts can be measured. There was a problem that the decrease could not be prevented.

The present invention has been developed to solve the above-described problems. In other words, the object of the present invention can be incorporated in the manufacturing process of sintered metal parts, and can accurately determine the bulk density of the filled particles before filling the mold and pressing the metal particles. Thus, it is an object of the present invention to provide an apparatus and a method for determining a bulk density of filled particles , which can detect a change in bulk density before pressure forming and can increase the yield of sintered metal parts.

According to the present invention, a filling particle bulk density determination apparatus for packed particles that are filled without gaps in a container having an open top and has a horizontal upper surface,
An elongated needle-like rod having a taper portion extending perpendicularly to the upper surface of the filler particles, having a constant cross-sectional shape, and gradually decreasing in cross-sectional dimension downward at the lower end;
A frictional force detecting device that grips the upper part or middle part of the needle-shaped rod, presses down at a constant speed from the upper surface of the filler particles to a predetermined depth, and detects an upward frictional force acting on the needle-shaped rod;
Packed particle bulk density determination apparatus characterized by having a bulk density determination apparatus for determining the bulk density of the filler particles from the frictional force is provided.

Further, according to the present invention, there is provided a method for determining a bulk density of packed particles of packed particles that are filled in a container having an upper opening without any gap and have a horizontal upper surface,
Gripping the upper part or middle part of an elongated needle-like rod having a taper part extending perpendicularly to the upper surface of the filler particles, having a constant cross-sectional shape and gradually decreasing in cross-sectional dimension toward the lower end;
The needle rod is pushed down from the upper surface of the filler particles to a predetermined depth at a constant speed, and an upward friction force acting on the needle rod is detected,
There is provided a method for determining a bulk density of packed particles, wherein the frictional force is compared with a predetermined threshold value to determine a bulk density of the packed particles .

  According to a preferred embodiment of the present invention, the needle rod is a cylindrical member having a diameter not less than 5 times and not more than 50 times the particle diameter of the packed particles, and the tapered portion has a height twice the diameter. As described above, the cone shape is 5 times or less.

The frictional force detection device includes an arm that grips an upper portion or an intermediate portion of the needle rod,
A traverse device that horizontally moves the arm between a measurement position where the needle-shaped rod is located at the top of the container and a retreat position retracted from the top of the container, and moves the arm up and down at the measurement position;
A force sensor for detecting a vertical force acting on the arm.

According to the above-described apparatus and method of the present invention, the frictional force detection device depresses the needle-shaped rod from the upper surface of the filled particles to a predetermined depth at a constant speed, and detects the upward frictional force acting on the needle-shaped rod at that time. However, since the bulk density of the filled particles is determined from the detected friction force by the bulk density determination device, it can be incorporated during the manufacturing process of sintered metal parts (after filling the mold and before pressure molding). is there.
Moreover, it was confirmed from the Example mentioned later that the bulk density of a filling particle can be determined with a sufficient precision compared with the conventional means based on JIS.
Therefore, a change in bulk density can be detected before pressure forming, and the yield of sintered metal parts can be increased.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is an overall configuration diagram of a packed particle bulk density determination apparatus according to the present invention.
In this figure, the filled particle bulk density determination apparatus 10 of the present invention is filled with no gaps in a container 12 having an open top, and has a horizontal upper surface 1 (hereinafter referred to as “filled particles”). 2 'is referred to as a ") and filler particles of bulk density determination apparatus comprises an elongate needle-like rod 14, the friction force detecting device 16 and the bulk density determination apparatus 18.

  The particles are, for example, aluminum powder (particle diameter: 150 to 500 μm) and iron powder (particle diameter: 75 to 150 μm), but the present invention is not limited to this, and other particles can be targeted.

In this example, the container 12 opened at the top is composed of a frame mold 11a constituting the outer edge of the container and a lower mold 11b constituting the bottom surface of the container.
The frame mold 11 a is a hollow member having an inner surface with a uniform horizontal cross-sectional shape. In this example, the upper end surface of the frame mold 11 a is fixed flush with the upper surface of the main body 3.
The upper part of the lower mold 11b is fitted to the inner surface of the frame mold 11a without any gap, can be moved up and down by an actuator (not shown), and can be lifted or lowered to take out the filled particles inside. .

  Above the lower mold 11b, there is provided an upper mold 11c that can be moved up and down by an actuator (not shown). The lower part of the upper mold 11c is fitted to the inner surface of the frame mold 11a without any gap, and the filler particles are pressed between the frame mold 11a, the lower mold 11b, and the upper mold 11c to be pressed into a desired shape. It is supposed to be.

  The acicular rod 14 extends perpendicularly to the upper surface of the filler particle 2 ′, has a constant cross-sectional shape, and has a tapered portion whose cross-sectional dimension gradually decreases downward at the lower end. The acicular rod 14 is preferably a cylindrical member having a diameter not less than 5 times and not more than 50 times the particle diameter of the packed particles, and the tapered portion has a conical shape whose height is not less than 2 times and not more than 5 times the diameter. It is.

The frictional force detection device 16 grips the upper part or the intermediate part of the needle rod 14, pushes it down from the upper surface of the packed particle 2 ′ to a predetermined depth h at a constant speed, and works upward friction force F acting on the needle rod 14. Is detected.
In this example, the frictional force detection device 16 includes an arm 13, a traverse device 15, and a force sensor 17.
In this example, the arm 13 is a bar-like member that holds the upper portion of the needle-like rod 14 at one end (right end in the figure) and extends horizontally.
In this example, the traverse device 15 supports the end of the arm 13 (left end in the figure) in a cantilever manner, and a measurement position where the needle rod 14 is located above the container 12 and a retreat position where the needle rod 14 is retracted from the top of the container 12. The arm 13 is moved horizontally between and the arm is moved up and down at the measurement position.
The force sensor 17 is, for example, a strain gauge attached to a part of the arm 13 and detects a vertical force acting on the arm 13.

  In this example, the bulk density determination device 18 includes a measurement device 18a that measures the vertical force acting on the arm 13 from the output of the force sensor 17, and a data analysis and display personal computer 18b. The data analysis and display personal computer 18b compares the measured vertical force (that is, the frictional force) with a predetermined threshold value, and determines the bulk density of the packed particles 2 '.

Using the apparatus described above, the packed particle bulk density determination method of the present invention comprises the following steps.
(1) Grasp the upper part or middle part of the elongated needle-like rod 14 having a taper part that extends perpendicularly to the upper surface of the packed particle 2 ′, has a constant cross-sectional shape, and gradually decreases in cross-sectional dimension downward. .
(2) The needle-like rod 14 is pushed down from the upper surface of the filled particle 2 ′ to a predetermined depth h at a constant speed, and an upward friction force F acting on the needle-like rod 14 is detected.
(3) The detected friction force F is compared with a predetermined threshold value set in advance, and the bulk density of the filled particles 2 ′ is determined.

Examples of the present invention will be described below.
(Comparison of JIS method for packing particle bulk density determination and the present invention)
In the process of forming a sintered metal product, iron powder is poured into a fixed-capacity mold container, and the excess amount is removed by scraping. It is a process management means.
However, when the bulk density of the packed particles filled by this method is accurately measured based on the weight, the filling amount (bulk density) varies with an error of 3 to 4% within the range of 2.475 to 2.570 g / cm 3. I found out. Reducing this variation is important in maintaining the quality of the sintered metal product, but it is difficult to incorporate a fixing for measuring the mass each time for management in the production line.

In order to solve this problem, we have invented an apparatus that can determine the bulk density with an accuracy of 1% by simply inserting the needle rod 14 into the iron powder filled in the mold (container 12) as described above.

1 Detection Method Frictional force F generated between rod 14 and particles according to the difference in particle filling rate when a thin rod (needle rod 14) is inserted into particle layer 2 ′ filled in a mold (container 12) Detect differences. The rod 14 is a thin metal rod as much as possible so as not to disturb the filling state of the iron powder particles.

2 Configuration of Measurement System FIG. 1 is a view showing a state in which a packed particle bulk density determination apparatus 10 of the present invention is installed in a mold (container 12). As described above, the device 10 of the present invention includes a needle-like rod 14 inserted into a particle layer, an arm 13 that supports the rod and detects a frictional force, a traverse device 15 that moves the arm back and forth, a measuring device 18a, data analysis and display. And a personal computer 18b.

3 Method for Confirming Detection Performance A performance confirmation test was performed using the above-described packed particle bulk density determination apparatus 10.
4 Test method Particles used: Aluminum powder (particle size: 150 to 500 μm), iron powder (particle size: 75 to 150 μm)
Bulk density (g / cm 3) of aluminum powder: A: 1.046 to 1.052, B: 5% increase (1.099 to 1.106). C: 8% increase (1.126 to 1.133)
Bulk density of iron powder (g / cm3): A: 2.476-2.484, B: 3% increase (2.536-2.570)

  A large number of particle layers were prepared in each bulk density range, rods were inserted into each of the bulk densities, the frictional force was measured, and whether a significant difference in the frictional force at each bulk density was observed and the degree of data variation were confirmed.

FIG. 2 is a diagram showing test results for iron powder. In this figure, the horizontal axis represents the particle layer depth, and the vertical axis represents the frictional force. The magnitude of the frictional force at each depth position in the process of inserting the rod to a depth of 30 mm was plotted.
As shown in this figure, a slight difference in bulk density causes a significant difference in frictional force between the needle rod 14 and iron powder, and the quality of the filling amount can be determined instantaneously. Moreover, since the measurement mechanism is simple, it is easy to incorporate it into the line.
The diameter of the rod 14 in this example is 2.5 mm, and the tapered portion is a cone shape having a length of 7.5 mm. Therefore, the diameter of the needle-like rod 14 is 16 to 33 times the particle size (75 to 150 μm) of the packed particles, and it is preferable that the needle-like rod 14 is a cylindrical member having a diameter of 5 to 50 times. Further, in this example, the tapered portion has a conical shape whose height is three times the diameter, and preferably has a conical shape that is not less than 2 times and not more than 5 times.

FIG. 3 is a diagram showing test results for aluminum powder. In this figure, the horizontal axis represents the particle layer depth, and the vertical axis represents the frictional force. The magnitude of the frictional force at each depth position in the process of inserting the rod to a depth of 30 mm was plotted.
In this example, the variation is large compared to FIG. 2, but the difference in the frictional force between the needle rod 14 and the iron powder is also noticeable due to the slight difference in the bulk density. I understand that I can do it. Moreover, since the measurement mechanism is simple, it is easy to incorporate it into the line.
The diameter of the needle rod 14 in this example was 2.5 mm, there was no taper part, and the lower end was a plane of the same diameter. The reason why the variation is large is considered to be that there is no taper portion. Accordingly, the tapered portion is preferably a conical shape whose height is three times the diameter as in FIG. 2, and is a conical shape that is not less than 2 times and not more than 5 times.
In this example, the diameter of the needle rod 14 is 5 to 17 times the particle size (150 to 500 μm) of the packed particles, and is a cylindrical member having a diameter of 5 to 50 times. Good.

5 Application to actual machine In actual machine application, data is acquired many times with an ideal bulk density particle layer, and upper and lower tolerance limits (for example, + 2%, -2%, etc.) are set based on the degree of variation. It is better to make a judgment of NG for those exceeding.

According to the above-described apparatus and method of the present invention, the frictional force detection device 10 pushes the needle rod 14 down from the upper surface of the filled particle 2 ′ to the predetermined depth h at a constant speed, The acting upward frictional force F is detected, and the bulk density determination device 18 determines the bulk density of the filler particles from the detected frictional force F. Before pressure molding).
Moreover, it was confirmed from the Examples that the bulk density of the packed particles can be accurately determined as compared with the conventional means based on JIS.
Therefore, a change in bulk density can be detected before pressure forming, and the yield of sintered metal parts can be increased.

  In addition, this invention is not limited to the Example and embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

It is a whole block diagram of the packed particle bulk density determination apparatus by this invention. It is a figure which shows the test result which makes iron powder object. It is a figure which shows the test result which makes aluminum powder object. It is a schematic diagram of the means of patent document 1.

Explanation of symbols

1 top surface, 2 particles, 2 'packed particles,
3 body,
10 packed particle bulk density determination device , 11a frame type,
11b Lower mold, 11c Upper mold,
12 container (die), 13 arm, 14 needle rod,
15 traverse device, 16 frictional force detection device,
17 force sensor, 18 bulk density determination device,
18a measuring device, 18b personal computer

Claims (4)

Filled particle bulk density determination device for filled particles having a horizontal upper surface filled in a container having an open top,
An elongated needle-like rod having a taper portion extending perpendicularly to the upper surface of the filler particles, having a constant cross-sectional shape, and gradually decreasing in cross-sectional dimension downward at the lower end;
A frictional force detecting device that grips the upper part or middle part of the needle-shaped rod, presses down at a constant speed from the upper surface of the filler particles to a predetermined depth, and detects an upward frictional force acting on the needle-shaped rod;
Packed particle bulk density determination apparatus characterized by having a bulk density determination apparatus for determining the bulk density of the filler particles from the frictional force. The needle rod is a cylindrical member having a diameter of 5 to 50 times the particle diameter of the filler particles, and the tapered portion is a cone having a height of 2 to 5 times the diameter. The packed particle bulk density determination apparatus according to claim 1, wherein: The frictional force detection device includes an arm that grips an upper portion or an intermediate portion of the needle rod,
A traverse device that horizontally moves the arm between a measurement position where the needle-shaped rod is located at the top of the container and a retreat position retracted from the top of the container, and moves the arm up and down at the measurement position;
The packed particle bulk density determination apparatus according to claim 1, further comprising a force sensor that detects a vertical force acting on the arm. Filled particle bulk density determination method for filled particles having a horizontal upper surface filled in a container having an open top,
Gripping the upper part or middle part of an elongated needle-like rod having a taper part extending perpendicularly to the upper surface of the filler particles, having a constant cross-sectional shape and gradually decreasing in cross-sectional dimension toward the lower end;
The needle rod is pushed down from the upper surface of the filler particles to a predetermined depth at a constant speed, and an upward friction force acting on the needle rod is detected,
A bulk density determination method for packed particles, wherein the friction force is compared with a predetermined threshold value to determine a bulk density of the packed particles .

Images