JPS6224909A - Method for detecting missing of saw tooth in sawing machine - Google Patents

Abstract

PURPOSE:To rapidly and surely detect missing of a saw tooth, by providing such an arrangement the missing of saw tooth is detected in accordance with the vibrating speed of a saw blade which is detected by a vibration sensor. CONSTITUTION:An electrical signal indicating a vibrating acceleration detected by a vibration sensor 6 provided to each bearing box 3 is delivered through an amplifier 7 to an integrator 8 which integrates the signal at one time to obtain a vibrating speed. Further, the vibrating speed signal is introduced through a bandpass filter 9 to remove frequency components other than those in a frequency range inherent to the device, and is then fed to a missing determining device 10 which determines the presence of missing of saw tooth.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting defects in saw teeth in a saw cutting machine for steel materials, etc.

[Conventional technology and its problems]

Rotary saws are widely used as pipe cutters and so-called edge millers. This type of saw cutter has the problem that the saw teeth break during operation, and if such a break occurs in even one of the saw teeth, the other saw teeth will also break immediately.
All the saw teeth will chip in a short period of time. For this reason, it is necessary to detect serration defects early and repair them by replacing them while the defects are still minor.

Such defects in the saw teeth can be detected by stopping and inspecting the saw teeth, but in order to detect the defects in the saw teeth at an early stage, it is necessary to stop the operation frequently, which significantly reduces work efficiency. On the other hand, there are ways to detect saw tooth loss during operation, such as: ■ Inspecting the cut end of the object to be cut, ■ Listening to abnormal noises during operation, and ■ Detecting an increase in the cutting current value. , n, the relationship between the detection element and the defect is not necessarily clear, and rapid and accurate detection of the defect cannot be expected.

[Means to solve the problem]

In view of these conventional problems, the inventors of the present invention have repeatedly studied a method for quickly and accurately detecting saw tooth loss during operation. It has been found that there is an extremely good correlation with sawtooth defects, regardless of feed rate, etc., and that sawtooth defects can be accurately detected by understanding changes in this vibration speed.

That is, the basic feature of the present invention is that the vibration velocity of the sawtooth is determined based on vibration measurement by a vibration sensor, and the sawtooth defect is detected based on the vibration velocity t.

The present invention will be explained in detail below.

A vibration sensor for measuring vibrations is attached to a sawtooth drive shaft, a bearing box of an intermediate shaft, a clamping means for an object to be cut, etc. This vibration sensor usually uses an acceleration sensor (such as a piezoelectric element type acceleration sensor), and the vibration speed is determined from the vibration acceleration detected by the n1 sensor. The present invention detects sawtooth defects based on the vibration speed of the sawtooth, but the vibration speed determined as described above includes high-frequency cutting frequency components in addition to vibration components specific to the device. Therefore, defects cannot be sufficiently determined from vibration velocities that include such high frequency components. Therefore, the cutting frequency component is removed from the vibration velocity obtained as described above, and a sawtooth defect cannot be determined due to the vibration component specific to the device. The cutting frequency is determined by the rotation frequency x the number of saw teeth, and the lower limit of the frequency band (cutting frequency) to be removed is set based on this n.

When detecting sawtooth defects from the above cutting vibration speed, follow the following three steps.
You can use the following method.

■ Compare the effective value (or average value) of the vibration speed with the effective value (or average value) of the vibration speed in the normal state to detect defects.

■ Compare the peak of the vibration velocity that occurs when the defective part hits the material to be cut with a reference value based on the effective value (or average value) to detect the defect.

(2) Count the number of times the signal obtained as in (2) above occurs within a constant rotational speed, and detect defects based on this number of times.

In the present invention, defect detection can be performed using one or more of the detection methods (1) to (4).

Figure 1 shows the vibration waveforms (
Waveform after 10-40Hz band pass filter processing)
The vibration waveform of the missing sawtooth is
A large pointed head (A) is formed at the part where the defective part contacts the material to be cut, and the vibration velocity not only at the defective part but also in the entire area is increased compared to normal saw teeth.

The method of the present invention utilizes such a vibration waveform, and the method (①) utilizes the fact that the vibration speed of the missing sawtooth increases over the entire range compared to that of the normal sawtooth, and the vibration of the normal sawtooth and the missing sawtooth is Deficiency is detected by comparing the effective speed values (or average values). In other words, in this case, the effective value (or average value) of the vibration velocity of the normal sawtooth is set as the threshold, and if the effective value (or average value) of the vibration velocity X exceeds this threshold, it is deleted. Detected as an occurrence.

In addition, in the method (■) above, the peak value P of the pointed head (A) is set to a reference value X・X based on the effective vibration velocity value (or average value)
Deficiency is detected by comparing with n (however, n is not limited to an integer). In this case, set Xxn as the threshold.

For example, if the peak value P is p>x x a (= n
), this is detected as a loss occurrence.

On the other hand, the peak (A) of the vibration waveform may occur not only when the saw tooth is damaged, but also when the saw tooth bites into the material to be cut, or when the saw tooth penetrates the material to be cut, and is simply the peak of the peak. Understand the value.

The above ■ Just compare this with the effective value (or average value)
With this method, it is conceivable that a non-defective cusp may be detected incorrectly as a serrated defect. Therefore, in the method (■) above, based on the method (■), the number M that occurs within a constant rotational speed where the peak value P exceeding M x n as described above is counted, and this n is the predetermined number (m pieces). When it exceeds n, it is detected as a defect occurrence.

FIG. 2 shows an example of an apparatus used in the method of the present invention.
(1) is a saw cutter, and (2) is a pair of saw teeth.

(3) is the bearing box of the sawtooth drive shaft (4), (5) is the material to be cut (pipe), and the vibration sensor (6) is attached to each bearing box (3).
It is set up in The vibration sensor (6) is composed of a piezoelectric element type acceleration sensor.

The electrical signal of the vibration acceleration detected by the vibration sensor (6) passes through the amplifier (7) and is then integrated once by the integrator (8) to determine the imaging speed based on the stiffness. As described above, this vibration velocity waveform includes a cutting frequency component in addition to a frequency component unique to the apparatus, and if this continues, the detection will vary widely and accurate defect detection cannot be expected.

For this reason, the shooting speed signal is passed through a band pass filter (9).
(low pass filter).

Frequency ranges other than those unique to the device (usually 30 to 40 Hz or less) are removed, and a defect determination device determines whether or not there is a defect. It should be noted that low frequency components (usually less than 10 Hz) of the vibration velocity cannot be expected to have sufficient integration accuracy, and therefore it is preferable to remove this frequency band with a band pass filter (9). .

In the defect determination device αq, a constant K of the normal sawtooth vibration velocity effective value (or average value), a numerical value n that determines the reference value (xx, n) based on the effective value ma, and the above reference value (xx
A reference number m of peak values exceeding n) is set respectively. In this device, 1, for example, 15 m See interval x
The effective value (or average value) of about 256 pieces (=3840 msec) of sampling data is given by n, above ■~■
Defectiveness is determined according to the detection method. Specifically, one of the methods from ■ to ■ above is adopted, and a loss alarm is issued when X) K (method of ■), P) XXn (method of ■), or M>m (method of ■). I tried to make it come out.

Alternatively, it is possible to perform two or more types of discrimination in parallel among the methods (1) to (2), and issue a defect alarm only when the conditions for defect detection are satisfied in all of these discriminations.

In addition, in the method (2) above, the number of peak values exceeding XXn can be known as the number of missing teeth.

The method of the present invention as described above can be applied to various saw cutting machines such as rotary saw cutting machines such as pipe cutting machines, edge millers, and billet coulters, as well as reciprocating saw cutting machines.

〔Example〕

FIG. 3 shows the results of a vibration speed detection test performed on normal saw teeth and defective saw teeth using a rotary saw tooth cutting machine for pipes (medium diameter pipes) equipped with a vibration sensor as shown in FIG. In addition, in this test, the vibration speed was set to 10 to 4.
0 Hz band pass number filter processing.

Depending on this, the vibration speed is 0.02 to 0.0 for normal sawtooth.
09 m1sec range, 0.2 to 0.45 with missing sawtooth
They are distributed in the range of 11117 B10, and it can be seen that defect detection based on the vibration speed is possible by setting the above-mentioned threshold value to around 0.15 was7 sec.

[Effects of the Invention] According to the present invention described above, it is possible to quickly and accurately detect saw tooth defects during operation, and by detecting defects at an early stage, it is possible to prevent a chain reaction of saw teeth defects and reduce saw tooth repair costs. can be achieved.

[Brief explanation of drawings]

FIG. 1 shows vibration velocity waveforms of normal sawtooths and defective sawtooths detected by the method of the present invention. FIG. 2 is an explanatory diagram showing an example of a device provided for the present invention. FIG. 3 shows the vibration speeds of n7S: a normal saw tooth and a defective saw tooth detected in the embodiment of the present invention. In the figure, (1) is a saw cutter, (2) is a saw blade, (6) is a vibration sensor, (8) is an integrator, (9) is a filter, and (9) is a defect determination device.

Claims (1)

[Claims] Sawtooth based on vibration measurements by vibration sensor Find the vibration speed of the saw and Saw cutting machine characterized by detecting tooth loss A method for detecting sawtooth defects in.