JPH06210436A - Device for controlling impacting force - Google Patents

Abstract

PURPOSE:To measure an impacting force during machining with the impacting force, to control the impacting force so that a suitable and definite impacting force is kept and to provide a impacting force controller which improve a life of a chisel. CONSTITUTION:An air controlling proportional valve 8 in order to control an air pressure being fed to an air cylinder 5 which is formed on a rear side of a chisel 3 energized to the retreating direction with a spring 4 and provided a hammer 6 impacting the chisel 3 is provided at inside, an acceleration sensor 10 detecting the impacting force when the chisel 3 impacts a subject to be impacted is attached on the chisel 3 or the air cylinder 5 side, a impacted force detecting signal of the acceleration sensor 10 is inputted in a controller 11, the air controlling proportional valve 8 is controlled with this controller 11 so that the impacting force is definite and the inputted air pressure of the air cylinder 5 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a striking force control device for measuring a striking force when a striking object is striking and controlling the striking force to a constant striking force.

[0002]

2. Description of the Related Art An air hammer device for hitting a casting product in order to drop the casting sand of the casting product is, for example, an actual flat blade 3
-36357. When hitting a work in such an air hammer device, it is necessary to measure the hitting force of the hammer device and apply an appropriate hitting force to the work. In order to impart this proper striking force to the work, the striking force is measured and controlled, and the conventional general striking force is measured by temporarily stopping the air hammer device,
A load cell is placed on the striking surface instead of the work, and the value output from the load cell by striking this is used for measurement.

[0003]

The above-mentioned conventional measurement of the impact force by the load cell is not an accurate measurement because the measurement is not performed by impacting the work during the actual machining. In addition, since the measurement is not performed during processing, it is not possible to preventively perform a preventive process, that is, to feed back a change in the impact force and always maintain an appropriate impact force.

In particular, in recent years, the thickness of aluminum castings has become thinner,
If an excessive impact force is applied to the work, dents and cracks will occur on the work, resulting in defects. Therefore, it is necessary to quantitatively measure the striking force and strike the work with the optimum striking force.

An object of the present invention is to provide a striking force control device which measures striking force during processing and feeds back a change in striking force to always maintain an appropriate striking force.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, a characteristic structure of the present invention is a chisel urged in a backward direction by a spring, and an air cylinder formed behind the chisel. An air control proportional valve that controls the air pressure supplied to the air cylinder, a hammer that is fitted in the air cylinder so that it can move back and forth, and that strikes the chisel, and a chisel that strikes an object to be hit. A striking force sensor for detecting striking force, and a controller for inputting a striking force detection signal of the striking force sensor and controlling the air control proportional valve so that the striking force becomes constant by comparing with a set value. It was done.

[0007]

With the above construction, the striking force sensor measures the striking force during processing, the striking force detection signal of the striking force sensor is processed by, for example, an FFT analyzer, and then compared with the set value. The proportional valve for air control is controlled so that is constant, and the air pressure supplied to the air cylinder is changed to always maintain an appropriate striking force.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is a striking device. This striking device 1 is axially movable in a housing 2 and has a spring 4
Of the chisel 3, the air cylinder 5 integrally connected to the housing 2 at the rear of the chisel 3, and the air cylinder 5 fitted in the air cylinder 5 so as to be movable back and forth. It is composed of a hammer 6 that taps the end.

The air cylinder 5 is provided with an air supply port 5a at the rear end thereof, and the air supply port 5a is connected to an air supply device 7 through an air control proportional valve 8 for controlling the supply air pressure. Piping is connected. An air outlet 5b is provided at the front end. The position of the air discharge port 5b is normally closed by the side wall of the hammer 6 as shown by the solid line in FIG. 1, but the hammer 6 moves to the forward end and taps the chisel 3 as shown by the dotted line in FIG. When you do, open
The air in the air cylinder 5 is set to be released to the atmosphere.

The striking device 1 has a chisel 3 as a work W.
A striking force sensor is provided for detecting a striking force when striking the (striking object). As a specific structure thereof, as shown in FIG. 1, a mounting member 9 is fixed to the tip end portion of the chisel 3, and the acceleration sensor 10 is mounted on the mounting member 9.

As another design modification, as shown in FIG. 2, a magnetizing portion 18 is provided at the rear end of the chisel 3, and the displacement sensor 1 is attached to the air cylinder 5 at a position corresponding to the magnetizing portion 18.
9 may be fixed so as to face the magnetized portion 18. The case of FIG. 2 is effective when the impact force of the chisel 3 is very strong. Further, as shown in FIG. 3, a strain measuring sensor 21 having a strain gauge 20 therein may be attached to the tip of the chisel 3. The impact force sensor of the acceleration sensor 10, the displacement sensor 19 and the strain measuring sensor 21 will be described with reference to FIG.
The acceleration sensor 10 will be described.

The acceleration sensor 10 is a controller 11
It is connected to the. The controller 11 includes a sensor amplifier 13 connected to the acceleration sensor 10 and an FFT connected to the sensor amplifier 13 via a filter 14.
It comprises an analyzer 15, a central processing unit (CPU) 12 to which the FFT analyzer 15 is connected, and an interface (IF) 16 connected to the central processing unit 12.

The air control proportional valve 8 is connected to an interface (IF) 16, and a display device 17 is also connected to the interface (IF).

In the operation of the striking device 1, the hammer 6 is moved forward by supplying the air whose air pressure is controlled by the air control proportional valve 8 to the air supply port 5a of the air cylinder 5. As a result, the chisel 3 is struck and the chisel 3 compresses the spring 4 and moves forward, and the tip of the chisel 3 strikes the work W.

When the hammer 6 operates at the forward end, the air discharge port 5b is opened, and the air in the air cylinder 5 is discharged to the atmosphere. By releasing the air in the air cylinder 5 to the atmosphere, the pressing force of the hammer 6 disappears,
The chisel 3 is moved backward by the spring 4 and returns to its original position. Therefore, by repeating the supply of air, the above-mentioned operation is repeated and the work W is continuously hit.

The above-mentioned striking operation causes the acceleration sensor 10 to detect the striking force, and the output of the acceleration sensor 10 (striking force detection signal) is input to the controller 11. The data from the acceleration sensor 10 has the frequency shown in FIG. 4, and the arrow A portion indicates the time of impact.

The acceleration sensor 10 based on the frequency shown in FIG.
Is amplified by the sensor amplifier 13, filtered by the filter 14, and input to the FFT analyzer 15. This FF
In the T-analyzer 15, the output of the acceleration sensor 10 having the frequency shown in FIG.
Processing) to obtain the data of the frequency shown in FIG. B of the data in FIG. 5 is a first-order term of acceleration (striking force), and C is a second-order term.

In the present invention, the striking force is held constant by observing the change in the frequency of the first-order term of the acceleration (striking force) subjected to the FFT process. That is, the striking force changes due to air leakage from the sliding surface of the chisel 3 and wear of the tip of the chisel 3. As a result, the acceleration is H as shown in FIG.
The frequency of is a normal value, but at the time of the above abnormality, the frequency H of the normal value is displaced E in the D direction to become the frequency I of the abnormal value. In FIG. 6, P is the peak value at the normal frequency H.

By measuring the displacement E and controlling the air control proportional valve 8 according to the displacement amount to change the air pressure supplied to the air cylinder 5, the frequency I of the abnormal value is in the direction opposite to the D direction. To the normal frequency H.

As shown in FIG. 7, most of the causes of the change in the acceleration (striking force) are the clearance 22 on the sliding surface of the chisel 3.
This is due to air leakage from the clearance 22. Due to this air leakage, the peak acceleration J decreases and the impact frequency K decreases at the same time, as indicated by the abnormal frequency I in FIG. 8 which is the same as FIG.

Therefore, the peak value P or the normal frequency H
If the air pressure supplied to the air cylinder 5 is increased so as to eliminate the displacement amount based on either of the above, the reduced peak value and the abnormal frequency I will return to normal.

As described above, the acceleration (striking force) also changes due to the wear of the tip of the chisel 3. The wear of the tip of the chisel 3 is abnormal wear of the tip side 23 of the chisel 3, as shown in FIG. This is a special case of the extreme wear of the chisel 3, but in such a case, the FFT processed acceleration (striking force) data is as shown in FIG.
The impact frequency is the same as the normal value frequency H and the abnormal value frequency I, and the peak value, that is, the peak acceleration J decreases.

In this case, usually, the air pressure supplied to the air cylinder 5 is raised to return to the waveform of the frequency H of the normal value based on only the change of the peak value, but even if the upper limit of the air pressure is exceeded, the peak value remains unchanged. If it does not return to the original state, the change in frequency is also measured, and if the frequency does not change, it can be determined that the chisel 3 is abnormally worn. Therefore, conversion of the chisel 3 is instructed.

As shown in FIG. 11, the lower limit L of the set value K of the peak value of the normal frequency H and the lower limit S of the set value R of the normal frequency H are set. .

As described above, these data are FFTs.
Analysis is performed by the analyzer 15, and the central processing unit 12 controls the proportional valve 8 for air control to change the air pressure supplied to the air cylinder 5 so that the striking force becomes constant, thereby constantly imparting a constant striking force in-line. It is a thing.

FIG. 12 shows the striking force control operation by the device of the present invention.
The flowchart will be described. Air pressure is supplied to the air cylinder 5 by the start 30, and the air hammer 6
Push down and tap the chisel 3. As a result, the chisel 3 descends against the force of the spring 4 and strikes the work W. At this time, it is desirable that the initial value of the air pressure that strikes the work W is an optimum value that strikes the work W obtained empirically. However, since the set value described later is determined based on this optimum value, even if there is some error in the initial value, the air pressure is corrected to an appropriate value by the action of this striking force control.

When the striking of the work W is started, acceleration data is measured by the acceleration sensor 10 attached to the chisel 3 (step 31), and this is measured by the FF of the controller 11.
The T analyzer 15 analyzes (step 32). Here, it is judged whether or not the amplitude of the primary impact frequency, that is, the peak value is within the set value (step 33), and within the set value, the display device 17 normally displays (step 37) and the process returns to step 31 to set. It strikes continuously with a constant striking force within the value.

If the peak value of the primary impact frequency is outside the set value in step 33, the central processing unit 12 controls the proportional valve 8 for air control in proportion to the amount of change from the set value, and the air cylinder 5 The input air pressure supplied to is changed (step 34). Then, in step 35, it is determined whether or not the current input air pressure exceeds the upper limit, and when it does not exceed the upper limit, the process returns to step 31, and steps 31 and thereafter are repeated. That is, in step 35, the input air pressure is changed according to the deviation between the peak value and the set value until the input air pressure exceeds the upper limit. When it is determined in step 35 that the input air pressure exceeds the upper limit and the input air pressure cannot be further increased, the process proceeds to step 36.

In step 36, it is determined whether the current frequency is lower than the lower limit S of the set value. If it is smaller than the lower limit S, as described above, both the peak value and the frequency are displaced. Therefore, it can be determined that the clearance of the sliding surface of the chisel 3 is large, and the process proceeds to step 38 to move the impact device 1 A warning device 17 is issued to replace the body or the chisel 3 with appropriate clearance.
To display.

If the current frequency is greater than the lower limit S of the set value in step 36, it can be determined that the frequency has not been displaced, and thus it can be determined that the tip of the chisel 3 is abnormally worn. Moving to step 39, a warning is displayed on the display device 17 to replace the chisel 3.

As described above, in the striking force control system of this embodiment, the detection value from the acceleration sensor 10 is processed by the FFT analyzer 15, the peak value and the frequency are compared with the set value, and the proportional valve 8 for air control is used. By controlling the air pressure by adjusting the, the striking force of the striking device 1 can be kept constant.

Further, when the striking force cannot be returned to the normal state even when the input air pressure exceeds the set value, it is possible to warn the replacement of the striking device 1 main body or the chisel 3 from the frequency state. The worker can perform proper maintenance work to quickly bring the impacting device 1 into a normal state.

[0033]

As described above, according to the present invention, the signal (output) detected by the striking force sensor of the striking force of the chisel that is hit by the air hammer to strike the work is compared with the set value, and the striking force is constant. Since the input air pressure supplied to the air cylinder of the air hammer is controlled by the air control proportional valve, the striking force is measured during striking force processing, and an appropriate constant striking force is measured. Allows control of striking force to hold.

As a result, it is possible to improve the quality of the work to be hammered, and particularly to a thin work, it is possible to give a proper hammering force according to the work, and cracks of the work are caused. To prevent. Also, by adjusting the input air pressure supplied to the air cylinder of the air hammer to an appropriate striking force for the work etc., it is possible to prevent excessive striking force from being applied to the work piece and to improve the life of the chisel. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a device of the present invention in which a controller and an air control circuit are shown together.

FIG. 2 is a sectional view showing another embodiment of the striking force sensor in the device of the present invention.

FIG. 3 is a sectional view showing another embodiment of the striking force sensor in the device of the present invention.

FIG. 4 is a waveform diagram showing output data from the acceleration sensor in the device of the present invention.

FIG. 5 is a waveform diagram showing data after FFT processing in the device of the present invention.

FIG. 6 is a waveform diagram showing amplitudes of a normal value frequency and an abnormal value frequency.

FIG. 7 is a sectional view showing a cause of a change in acceleration (striking force) due to air leakage.

FIG. 8 is a waveform chart showing data after FFT processing in the case of a change in acceleration (striking force) due to air leakage.

[Fig. 9] Acceleration (percussion force) due to abnormal wear of the tip of the chisel
Cross-sectional view showing the cause of change in

FIG. 10 is a waveform diagram showing data after FFT processing when the acceleration (striking force) changes due to air leakage.

FIG. 11 is a diagram showing a lower limit of a normal frequency peak value setting value and a lower limit of a normal frequency setting value.

FIG. 12 is a flowchart showing the operation of the device of the present invention.

[Explanation of symbols]

 1 Strike Device 2 Housing 3 Chisel 4 Spring 5 Air Cylinder 6 Hammer 7 Air Supply Device 8 Air Control Proportional Valve 10 Acceleration Sensor 11 Controller 12 Central Processing Unit 15 FFT Analyzer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuya Sakai 1-1 Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (72) Inventor Takeo Furuya 1-cho, Toyota-shi, Aichi Toyota Motor Corporation In-house (72) Inventor Mikiya Nozaki 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Tomohiko Nishiyama 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. A chisel urged in a backward direction by a spring, an air cylinder formed behind the chisel, an air control proportional valve for controlling an air pressure supplied to the air cylinder, and the air cylinder. A hammer, which is fitted so as to be able to move forward and backward, strikes the chisel, a striking force sensor that detects the striking force when the chisel strikes a hit object, and a striking force detection signal of this striking force sensor is input. And an impact force control device comprising a controller for controlling the air control proportional valve so that the striking force becomes constant by comparing with a set value.