JPH11119836A - Powder supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder supply device capable of detecting the intrusion of foreign matter when the power supply device is actually operating. SOLUTION: This device is a power supply device that has an vibrator 10, of which tip part elliptically vibrates when a specified resonance frequency is applied to a piezoelectric element 1, a power carrier path 20 formed at the top end of the vibrator 10, and a hopper 30 for storing a power P and feeding the power P to the power carrier path 20, and it also has a load cell for measuring a weight of the powder supply device body and measuring a weight of the power P supplied and a differentiation circuit 44 for differentiating a weight change of the powder P the load cell 40 measures, calculating an instantaneous amount of supply and outputting it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder supply apparatus, and more particularly, to a powder supply apparatus capable of detecting an abnormality in which foreign matter such as dust is mixed in powder.

[0002]

2. Description of the Related Art Conventionally, as a powder supply apparatus, an apparatus using an ultrasonic motor using an ultrasonic vibrator is well known. This powder feeder uses the fact that the ultrasonic transducer generates mechanical vibrations of the piezoelectric element at the resonance frequency by electric energy, and generates the mechanical vibration in the vibrator to convey the powder. I have. That is, when an AC drive voltage having a resonance frequency is applied to an ultrasonic vibration motor configured to simultaneously generate longitudinal vibration (longitudinal vibration) and bending vibration, elliptical vibration occurs at the tip, and a pipe is placed at the tip. Is attached, powder is supplied into a pipe, and the powder is conveyed in a certain direction by elliptical vibration.

The supply amount of the powder is controlled by the following control. That is, by intermittently applying the drive voltage to the ultrasonic motor, the ratio of the drive voltage per cycle (duty ratio) is changed, thereby changing the output to the ultrasonic motor and supplying the powder. Is controlling. For example, an AND of a resonance frequency oscillating circuit oscillating at a resonance frequency and a clock generator for duty ratio control for changing a duty ratio, for example.
Then, the output is amplified and applied to the vibrating body.

Further, in order to improve the accuracy of the control, feedback control is performed by a control system as shown in a block diagram of FIG. That is, the weight of the powder is measured by the load cell 40 as a load sensor, the output signal of the sensor is amplified by the load cell amplifier 41, and the output signal is fed back to the microcomputer system 43 (duty ratio control) via the A / D converter 42. Means). Then, in the microcomputer system 43, based on the output amplification signal, the drive circuit 11 for driving the ultrasonic wave is operated by the calculated duty ratio clock signal. Then, a drive voltage signal is applied to the ultrasonic motor 1, and the ultrasonic motor 1 operates. At this time, based on the output signal from the load cell 40, the microcomputer system 43
Since the optimum duty ratio is calculated, the powder supply amount can be controlled optimally.

[0005] For example, in a system in which metal powder is supplied to a process using a conventional powder supply device and surface processing is performed, a metal powder having an average particle diameter of 0.1 mm is added to a metal powder having an average particle diameter of 0.1 mm in a process after surface processing. It is detected whether a foreign matter of about 5 mm to 1 mm has entered. Then, when foreign matter is detected in a subsequent process, the system shown in FIG. 8 performs verification of the powder supply device. That is, a method in which the powder is supplied to a beaker on the electronic balance 50, the measured value is read in real time by the personal computer 51 connected by the RS232C52, and the occurrence of abnormality is checked. If foreign matter is mixed, clogging occurs, and a large fluctuation occurs in the instantaneous supply amount. By observing the change, foreign matter can be found.

[0006]

However, according to the method of measuring with the electronic balance 50, as shown in FIG. 9, a signal L with a large supply amount is generated every 0.1 to 0.5 seconds of the sampling time in the personal computer 51. Measured. This is a phenomenon that occurs because the supply amount is constant, but there is a moment when the supply amount cannot be measured when the sampling pulse is generated, and the supply amount at that moment is added to the next moment. Therefore, when an abnormality occurs, there is a problem that it is difficult to distinguish the signal L from the signal L. Also, since this measurement method cannot be performed in-line while the powder supply device is in actual operation,
Eventually, only an abnormality was detected in the subsequent process. For this reason, there has been a demand for a system capable of detecting an abnormality in real time in-line.

Accordingly, the present invention has been made to solve the above-mentioned problems, and provides a powder supply device capable of detecting that a foreign substance has entered during the actual operation of the powder supply device. The purpose is to do.

[0008]

Means for Solving the Problems In order to solve the above problems, the powder supply apparatus of the present invention has the following configuration. (1) A vibrator whose tip portion performs an elliptical vibration when a predetermined resonance frequency is applied to the piezoelectric element, a powder transport path formed at the tip of the vibrator, and a powder transport path for storing the powder and storing the powder. A powder feeder having a hopper for feeding powder to the feeder, wherein the feeder measuring unit measures the weight of the powder feeder main body and measures the weight of the supplied powder. An instantaneous supply amount detecting means for calculating and outputting an instantaneous supply amount by differentiating the measured change in weight of the powder.

(2) In the apparatus described in (1), the instantaneous supply amount detection means outputs an abnormal signal when the instantaneous supply amount exceeds a predetermined threshold. . (3) The apparatus according to (1) or (2), further comprising an instantaneous supply amount display means for displaying the instantaneous supply amount.

Next, the operation of the powder supply apparatus having the above configuration will be described. When a predetermined resonance frequency is applied to the piezoelectric element forming the vibrating body, the tip of the vibrating body performs elliptical vibration. At the tip of the vibrating body, a pipe-shaped powder conveying path is held, and by vibrating the tip of the vibrating body elliptically,
The powder in the pipe is conveyed. Powder is supplied to the pipe from a hopper. According to this supply device, the supply of powder starts immediately when a voltage is applied, and the supply of the powder stops instantly when the voltage is cut off.At the same time, the supply voltage and the flow rate of the powder have a linear relationship. The body can be supplied with high accuracy. In particular, since a constant flow rate can always be maintained, it is convenient when, for example, metal powder is uniformly supplied for metal surface processing.

The supply amount measuring means includes a vibrating body, a powder conveying path,
The weight of the powder supply device body including the hopper is measured in real time by a load cell or the like, and the weight of the supplied powder is measured. The instantaneous supply amount detection means calculates and outputs an instantaneous supply amount by differentiating the weight change of the powder measured by the supply amount measurement means. As a result, the instantaneous powder flow rate can always be grasped, and by monitoring the instantaneous powder flow rate, the intrusion of foreign matter can be detected.

For example, the instantaneous supply amount detecting means outputs an abnormal signal when the instantaneous supply amount exceeds a predetermined threshold. If foreign matter is mixed in the powder, the powder tends to be clogged in the tube, and the flow rate changes instantaneously. The instantaneous supply amount detecting means detects this change and outputs an abnormal signal. As a result, the control computer in the production process can recognize the abnormality and stop the line. Then, the occurrence of defective products can be stopped immediately, and the normal operation of the line can be started quickly. Also, since the instantaneous supply amount display means always displays the instantaneous supply amount,
It can be confirmed that the powder supply device is operating normally.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a powder supply apparatus according to one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the overall configuration of the powder supply device, and FIG. 4 shows the structure of the main body of the powder supply device. First, the structure and operation of the main body of the powder supply device will be described. In FIG. 4, the vibrating body 10 is a so-called linear type ultrasonic motor, and two flat plate-shaped piezoelectric elements 1 are laminated via an electrode plate (not shown).
The two surfaces are sandwiched between a substantially cylindrical metal horn 2a and a substantially cylindrical metal back horn 2b. The vibrating body 10 is inserted through a through-hole penetrating the back horn 2b and the central portion of the piezoelectric element 1, and one end of the horn 2
It is fixed to the fixing member 4 by the bolt 3 fastened to a. The tip 2c of the horn 2a has two chamfers, and is provided with a through hole 2d for inserting a pipe described later.

A powder supply pipe 20 through which the powder flows is penetrated and fixed to the through hole 2d. The left end 21 of the powder supply pipe 20 in the figure is slightly bent downward so that the powder P conveyed from the right in the figure can easily fall and move from the end 21 of the pipe 20. ing. On the other hand, the right end portion 22 of the pipe 20 in the drawing is bent slightly upward, so that the powder P supplied from the hopper body 30 can be easily transported to the left side in the drawing.

The hopper body 30 stores the powder P and gradually supplies the powder to the pipe 20, and the bottom 31 has a funnel shape. A tube 32 is connected to the bottom 31, and the other end of the tube 32 is connected to an end 22 of the powder supply pipe 20. Therefore,
The powder P charged into the hopper body 30 is supplied to the pipe 20 via the tube 32. In addition, tube 3
For 2, a flexible material is selected so as not to hinder the vibration of the vibrating body 10, and in this example, a nylon tube is used.

FIG. 5 shows the results of measuring the frequency characteristics of the input impedance of the vibrating body 10 using an impedance analyzer. From this result, the resonance frequency F of the vibrating body 10
It turns out that r is about 29.4 kHz. When driven at this resonance frequency Fr, it vibrates greatly. on the other hand,
When driven at a frequency deviating from the resonance frequency, that is, at a non-resonance frequency, since the driving energy cannot be injected due to an increase in impedance, almost no vibration occurs.
Therefore, in this embodiment, the driving of the vibrating body 10 is turned on / off by alternately applying the resonance frequency and the non-resonance frequency. Incidentally, even if the drive voltage is not applied during the period in which the non-resonant frequency is applied, the drive of the vibrating body 10 can be similarly turned on / off.

Here, the state of vibration when the vibrating body 10 is driven at the resonance frequency will be described. When the piezoelectric element 1 is driven at the resonance frequency, the piezoelectric element expands and contracts, so that the vibrating body 10 bends and vibrates as shown in FIG. This vibration is
This is a composite vibration of vibration of expansion and contraction (vertical vibration) in the vertical direction in the figure and bending vibration (bending vibration) in the horizontal direction of the figure.

To explain in more detail one cycle of the vibration, the vibration is performed as shown in FIG. In addition,
In FIG. 7, a black dot is formed at the center of the front end to make it easier to understand the movement of the front end (lower end in the figure). First, t = 0
In FIG. 7A, the tip (black dot) is bent so as to be located on the right side. Then, t = π after 1/4 cycle
/ 2 (FIG. 7 (b)), the vibrating body shrinks, and the tip (black dot) is located on the upper side in the figure. Further, t = π (FIG. 7)
In (c)), the tip portion (black dot) is bent so as to be located on the left side. Further, t = 3π / 2 after 1/4 cycle
In FIG. 7D, the vibrating body is elongated, and the tip (black dot) is located on the lower side in the figure. Therefore, when the movement of the sunspot is traced for one cycle, it can be understood that the ellipse moves as shown in FIG.

Therefore, a pipe is attached to this tip,
When the powder is supplied into the pipe, the powder is lifted but is accelerated in the left direction in the figure and is conveyed to the left. Then, the ratio of time for driving at the resonance frequency is adjusted, that is, the duty ratio is changed to adjust the amount of powder transported (cutout amount). At this time, the hopper body 30
The weight of the powder P inside is measured by a load cell, and the output signal is fed back to the microcomputer system. Based on this feedback signal, a duty ratio control signal optimally calculated by the microcomputer system is sent to the drive circuit, and the drive voltage VACT is applied to the vibrating body 10 for a time corresponding to the duty ratio, whereby the powder P The cutting amount and the actual flow rate are controlled. The microcomputer system includes a duty ratio control unit, a feeder calibration storage unit, a duty ratio calculation unit, and a feedback unit.

When a predetermined resonance frequency is applied to the piezoelectric element 1 constituting the vibrating body, the tip of the vibrating body 1 performs an elliptical vibration. A pipe-shaped powder conveying path 20 is provided at the tip of the vibrating body 1.
Is held, and the powder in the pipe 20 is conveyed by the tip of the vibrator vibrating elliptically. Powder is supplied to the pipe 20 from the hopper 30. According to this supply device, the supply of the powder starts immediately when a voltage is applied, and the supply of the powder stops instantly when the voltage is cut off. At the same time, the output voltage of the load cell 40 and the mass of the powder are the same as in FIG.
As shown in (1), the powder can be supplied with high accuracy because of the linear relationship. In particular, since a constant flow rate can always be maintained, it is convenient when it is necessary to uniformly supply metal powder for metal surface processing.

Next, a method of detecting the instantaneous supply amount, which is a main part of the present invention, will be described. The powder supply device of the present invention,
As shown in FIG. 1, the output of the load cell 40 is amplified by a load cell amplifier 41 and then input to a differentiating circuit 44 constituted by a hardware circuit. The differentiating circuit 44 is a general circuit for differentiating the amplified analog data in a hardware manner, and a detailed description thereof will be omitted. The load cell 40 is a powder P
Is measured in real time, and by differentiating the reduced amount by the differentiating circuit 44, the supply amount of the powder P supplied by the powder supply device per sampling time can be known in real time. . In the differentiating circuit 44, the supply amount of 1.0 g / sec is calibrated to 1.0 V.
The output of the differentiating circuit 44 is output to the display 45 at the same time as being output to the microcomputer system 43. The microcomputer system 43 has an instantaneous supply amount detection program that determines that an abnormality has occurred when the supply amount has changed to more than + 5% or has changed to less than -5%, and outputs an abnormal signal.

Next, the operation will be described. FIG. 2 shows the output voltage of the differentiating circuit 44. In a normal state, the supply amount is almost constant, and the output value of the differentiating circuit 44 is within the threshold value plus or minus 5%. When a foreign matter mixing abnormality occurs, the output voltage of the differentiating circuit 44 shows an abnormal value as shown by E in FIG. 2 and exceeds the threshold. The instantaneous supply amount detection program of the microcomputer system 43 determines that this voltage is abnormal, and outputs an abnormal signal to the line control computer. When a foreign substance having a particle size of 0.5 to 1 mm is mixed, as shown in FIG. 2, the threshold value is exceeded from the initial stage, so that an abnormality can be detected in the initial stage of the occurrence, thereby reducing the occurrence of defective products. it can.

As described in detail above, according to the powder supply device of the present embodiment, the vibrating body 10 whose tip portion performs elliptical vibration when a predetermined resonance frequency is applied to the piezoelectric element 1,
A powder supply pipe 20 formed at the tip of the vibrating body 10,
And a hopper 30 for storing the powder P and feeding the powder P to the powder supply pipe 20. The powder supply device measures the weight of the powder supply device main body and determines the weight of the supplied powder P. And the instantaneous supply amount detecting means for calculating and outputting the instantaneous supply amount by differentiating the weight change of the powder P measured by the load cell 40. The body flow rate can always be grasped, and by monitoring the instantaneous powder flow rate, the intrusion of foreign matter can be detected.

Further, according to the powder supply device of the present embodiment, the instantaneous supply amount detection means outputs an abnormal signal when the instantaneous supply amount exceeds the predetermined threshold, so that the instantaneous supply amount is mixed in the powder. When the foreign matter that has been trapped in the pipe tends to be clogged and the flow rate changes instantaneously, this change is detected and an abnormal signal is output, so the control computer in the production process should know the abnormality and stop the line etc. Can be. Then, the occurrence of defective products can be stopped immediately, and the normal operation of the line can be started quickly. Further, according to the powder supply device of the present embodiment, the instantaneous indicator 4 for displaying the instantaneous supply amount is provided.
5, the operator can confirm that the powder supply device is operating normally.

The present invention is not limited to the above embodiment, but can be applied to various applications. For example, the display 45
May be provided with a means for comparing with a threshold.

[0026]

According to the powder supply device of the present invention, the vibrator whose tip portion performs elliptical vibration when a predetermined resonance frequency is applied to the piezoelectric element, and the powder conveying path formed at the tip portion of the vibrator, And a hopper for storing the powder and feeding the powder to a powder conveying path, wherein the weight of the powder supply device body is measured and the weight of the supplied powder is measured. Since it has an amount measuring means and an instantaneous supply amount detecting means for calculating and outputting an instantaneous supply amount by differentiating the weight change of the powder measured by the supply amount measuring means, The flow rate can always be grasped, and by monitoring the instantaneous powder flow rate, the intrusion of foreign matter can be detected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a powder supply device according to an embodiment of the present invention.

2 is an output signal diagram of a differentiating circuit 44. FIG.

FIG. 3 is a data diagram showing a relationship between an output voltage of a load cell 40 and a mass of a powder supply device.

FIG. 4 is a cross-sectional view illustrating a configuration of a powder supply device main body.

FIG. 5 is a data diagram showing a frequency characteristic of an input impedance of the vibrating body 10;

FIG. 6 is a first explanatory view of driving of the vibrating body 10.

FIG. 7 is a second explanatory diagram of driving of the vibrating body 10.

FIG. 8 is a block diagram showing a configuration of a conventional powder supply device.

FIG. 9 is a data diagram showing a test method of a conventional powder supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2a Metal horn 2b Back horn 2c Tip 2d Through hole 3 Bolt 4 Fixing member 20, 21 Powder supply pipe 30 Hopper body 31 Bottom 32 Tube 40 Load cell 43 Microcomputer system 44 Differentiation circuit 45 Display P Powder

Claims (3)

[Claims] 1. A vibrator whose tip portion performs an elliptical vibration when a predetermined resonance frequency is applied to a piezoelectric element, a powder conveying path formed at a tip portion of the vibrator, and a powder storing and storing the powder. A powder supply device having a hopper for feeding the powder into the transport path, a supply amount measurement unit that measures the weight of the powder supply device main body and measures the weight of the supplied powder, and the supply amount measurement unit. And an instantaneous supply amount detecting means for calculating and outputting an instantaneous supply amount by differentiating a change in the weight of the powder measured by the apparatus. 2. The powder supply device according to claim 1, wherein the instantaneous supply amount detection unit outputs an abnormal signal when the instantaneous supply amount exceeds a predetermined threshold. Powder supply device. 3. The powder supply device according to claim 1, further comprising an instantaneous supply amount display means for displaying the instantaneous supply amount.