JPH074734B2 - Cutting condition monitoring device for cutting equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device for monitoring a cutting condition of a cutting device such as a chamfering machine that cuts an end surface of a steel material such as a steel pipe or a round bar.

<Prior Art> Normally, steel materials such as steel pipes and round bars manufactured by rolling mills are cut into a predetermined length to make products.
The chamfering process is performed in order to remove the unevenness or burrs of the cut surface generated at the stage of the cutting process, or to satisfy the requirements of the customer such as the end chamfering and the outer chamfering.

As a chamfering machine for performing this chamfering process, for example, as shown in FIG. 3, a tool 6 having a tool holder 4 with a tool 3 attached thereto via a rotary shaft 5 while a steel pipe 1 is fixed by a clamp 2. In many cases, the cutting tool 3 is pressed against the end surface of the steel pipe 1 by the servo motor 7 while rotating on the same axis as the shaft center of the steel pipe 1.

There are three types of cutting tool 3 used for cutting, end chamfering called facing, inner chamfering called reaming, and outer chamfering called chamfering or beveling, and one or three of them can be combined depending on the purpose. Chamfering is performed by setting the tool on the bite holder 4.

For example, FIG. 4 (a) shows a case of chamfering, in which the bevel tip 9a clamped to the tip of the shank 8a fixed to the bite holder 4 cuts the outer surface. Tip 9 clamped to 8b, 8c
The root face on the end face and the chamfer on the inner face are also cut by b and 9c at the same time.

Further, FIG. 4 (b) shows an end chamfer, in which the end surface is cut by the facing tip 9d clamped to the shank 8d, and at the same time, the outer surface is cut by the tips 9e, 9f clamped to the shank 8e, 8f. The chamfer and inner reaming are also cut.

<Problems to be Solved by the Invention> By the way, in the chamfering work as described above, at least one worker must be arranged for each chamfering machine in order to monitor the cutting state of the chamfering machine. There is a problem of not becoming. The reason is as follows.

It is not possible to predict when cutting defects will occur due to chipping or wear of the cutting tool, so constant monitoring by workers is required.

When the inventors investigated the bite loss, it was found that crater wear and cracks were the main ones, and it was due to heat cracks and impact force due to internal burrs that occurred during constant-length cutting in the previous process. Is known.

If the cutting tool is found to be missing or worn, it must be replaced immediately and chamfered again.

In addition, at the chamfer inspection site provided downstream of this chamfering process, in addition to the normal end face inspection, the chamfering part is checked to ensure the chamfering quality and prevent human error by the chamfering machine operator. There is also a problem in that the work load is increased.

To deal with such a problem, for example, Japanese Patent Laid-Open No. 61-38
As disclosed in Japanese Patent No. 847, cutting vibration or acceleration during cutting is measured, and area power of a predetermined frequency band in a first time zone and area power of a predetermined frequency band in a second time zone are measured. There has been proposed a method of detecting a change in the cutting ratio, a cutting tool abnormality, etc.

However, with this method, it is necessary to search for a frequency band suitable for cutting monitoring in advance, and it is also necessary to investigate the suitability of the frequency band after maintaining the cutting device. Moreover, in order to obtain the area power of the frequency band, an FFT (Fast Fourier Analysis Device) is required, but unless the input signal is properly preprocessed, the optimum analysis result suitable for the purpose cannot be obtained. However, it is difficult to obtain reproducible results because there are difficulties in use. There is also a problem that the structure of the device is complicated and expensive.

The present invention has been made to solve the above problems, can be easily installed in existing cutting equipment, and also using a commercially available inexpensive measuring instrument, damage and wear of the cutting tool during cutting. It is an object of the present invention to provide a device capable of detecting such as.

<Means for Solving the Problem> The inventors of the present invention have made extensive studies on cutting monitoring of a cutting device, and as a result, accurately detect a cutting tool defect or wear by measuring an axial cutting reaction force of the cutting device. Based on this finding, the present invention has been completed.

That is, the gist of the present invention is a device for gripping a part of a steel material to be cut by a gripping device and monitoring a cutting situation when cutting an end surface of the steel material with a cutting tool, A washer-type compression strain gauge load cell that is attached to the opposite side of the fixing bolt that fixes the gripping device to the base and measures the axial cutting reaction force from the start of cutting to the end of cutting when cutting steel, Using the average value calculated from the peak value of the axial cutting reaction force measured during the cutting of the first multiple lots,
A setting device for setting the defect judgment set value, the wear judgment set value, and the incomplete cutting judgment set value, and the axial cutting reaction force at the time of cutting the cutting steel material measured by the washer-type compression strain gauge load cell are input, The loss determination set value, the wear determination set value, and the incomplete cutting determination set value set by the setting device are sequentially compared, and when it is determined that any one of the set values is exceeded, the alarm control device is in an abnormal state. The above object is achieved by a cutting condition monitoring device for a cutting device, which comprises an arithmetic device for issuing an alarm signal.

<Operation> It is well known that the end face machining of steel material is performed by the combined torque of the rotational direction torque and the shaft longitudinal direction torque. Among them, the torque in the rotation direction can be obtained by measuring a load current of a driving device such as a motor that rotates a bite holder equipped with a bite. However, since the moment of inertia of these drive systems is large, it may be possible to detect a large loss of the bite only by the torque in the rotational direction, but it is difficult to detect when a small defect or wear occurs.

On the other hand, the axial longitudinal torque is a force that acts directly on the cutting tool, so by measuring this axial longitudinal torque,
It is possible to detect small torque changes caused by chipping or wear of the cutting tool.

Therefore, the inventors of the present invention investigated various load cells capable of accurately detecting the cutting torque at the time of cutting by the cutting device, and found that "Bolt Force Sensor (BOLT F
ORCE SENSOR) "washer type compression strain gauge load cell (hereinafter abbreviated as load washer) has been found to be suitable.

The situation of the measurement experiment using the load washer will be described in detail below.

First, as shown in FIG. 5, the load washers (model No.3711-312, capacity 3175 kg) 10a, 10b, 10c are attached to the assembly bolts 11a, 11b, 11c at the three points A, B, C of the chuck device 2. And attach them with nuts 12a, 12b, 12c to secure the steel pipe 1
The axial cutting reaction force (hereinafter, simply referred to as reaction force) generated by the torque in the axial longitudinal direction during cutting the end face of was measured.

The results are shown in FIGS. 6 (a), (b) and (c), respectively. As is clear from the figure, the measured value of the reaction force at point C is
Compared to the other two points A and B, the characteristics of the cutting device are better represented, and it is clear that it is suitable for monitoring cutting.

Then, using the load washer 11c at the point C, a comparative experiment was carried out between a normal inner surface tip and a large amount of wear on a steel pipe having an outer diameter of 159.0 mmφ × wall thickness of 6.0 mmt. The state of change in the reaction force at that time is shown in FIG. 7 (a) on average for each piece. For pieces No. 1 to 3 in which the inner chip is normal, the reaction force is about 20 kg, whereas in the case of the inner chip with a large amount of wear, piece N
All of o.4 and 5 have a difference of 21% or more and 5% or more, and the significant difference is clear.

Further, in the same manner, FIG. 7 (b) shows the result of comparative measurement of the changes in the reaction forces of the normal end face chip and the defective end face chip. Piece with normal end face tip
For Nos. 1 to 3, the reaction force is almost 20 kg, while
Pieces Nos. 4 and 5 using defective chips all have a difference of 23 kg or more and 15% or more, and the significant difference is clear.

When various measurement tests were conducted based on these findings, the reaction force during cutting showed that the outer diameter of the material to be cut, the pipe thickness and its grade during normal cutting and when the cutting tool was damaged. It was also found that it changes depending on factors such as the shape of the end face machining, the spindle speed of the chamfering machine, and the cutting feed rate. Therefore, it is necessary to standardize the reaction force during normal cutting with respect to the above conditions.

FIG. 8 shows an example of reaction force characteristics of one cycle of cutting when the tip is normal. In the figure, the reaction force T
When the time t _S in the chat to the start of the measurement from the King start, rising early from the reaction force zero point T _o, time of chucking end
It becomes the initial reaction force value T _S at t ₁ and reaches the peak reaction force value T _p after the time t ₂ when the cutting is started. Then, during the time period Δt (= t ₃ −t ₂ ) up to the time t ₃ when the cutting is completed, the peak reaction force T _p appears while the reaction force T varies within the width of ΔT, and the measurement end time t _E
In return to again T _o.

Therefore, the peak reaction force T _p as a standard value, if to compare the peak reaction force T _p at the time when cutting the steel pipe of the same lot in the same conditions, it is possible to detect defects or wear status byte Is.

However, in reality, the peak reaction force is affected by the fluctuation of the tightening of the load washer or chucking device.
Since T _p or the initial reaction force value T _S fluctuates, in order to eliminate these effects, the standard value is integrated with the reaction force T at Δt from the cutting start time t ₂ to the cutting completion time t ₃ , and The integrated reaction force value S may be obtained based on the equation (1).

Alternatively, regarding the initial reaction force value T _S as tare, the following (2)
As shown in the equation, the difference T _M between the peak reaction force value T _p and the initial reaction force value T _S
May be monitored.

T _M = T _p −T _S ………… (2) Note that the peak reaction force value T _p must be measured by sampling, but the maximum sampling value at a predetermined sampling time is selected. You can do it like this.

Here, the above-mentioned peak reaction force value T _p or integrated reaction force value S,
When the reaction force difference value T _M is used as a standard value, it is unstable with only one measured value. Therefore, it is preferable to measure a plurality of measured values such as three and use the average value thereof.

When using the standard value obtained in this way for chipping judgment or wear judgment or incomplete cutting judgment,
The following processing is performed to set each set value.

In the case of the defect determination mode: The set value T _pS when the peak reaction force value T _p is used as the standard value in the defect determination mode is determined by the following formula (3).

T _pS = k ₁₁ · _p (3) Here, k ₁₁ is a constant and _p is the average value of the peak reaction force values.

From the above-mentioned measurement results of the load washer, it is known that the magnitude of the reaction force when the bite is missing is 15% or more of the normal value. Therefore, this constant k ₁₁ is
For example, the coefficient may be 1.15.

Then, when the set value T _pS is exceeded, it is determined that the bite is “missing” and an alarm is issued, and an interlock is provided to take measures such as an emergency stop of the cutting device.

When the integrated reaction force value S and reaction force difference value T _M are standard values,
The following equations (4) and (5) may be used.

S _S = k ₁₂ ········ (4) T _MS = k ₁₃ · _M ······ (5) where k ₁₂ and k ₁₃ are constants, and _M is the standard value of the integral reaction force. It is the average of the value S and the reaction force difference value T _M.

In the wear determination mode: The set value T _pT when the peak reaction force value _p is used as the standard value in the wear determination mode is determined by the following equation (6).

T _pT = k ₂₁ · _p (6) Here, k ₂₁ is a constant.

Similar to the determination of the defect determination set value described above, it is known from the measurement experimental results that the magnitude of the reaction force when the bite is worn is 5% or more of the normal value, so that the constant k ₂₁ The value is set to 1.05, for example. Then, when the set value T _pT is exceeded, it is determined that the bite is “abraded” and an alarm is issued.

When the integral reaction force value and the reaction force difference value _M are standard values, the following equations (7) and (8) may be used.

S _T = k ₂₂ ······················ (7) T _MT = k ₂₃ · _M ····························· (8) where k ₂₂ and k ₂₃ are constants.

In the case of incomplete cutting determination mode; The set value T _pU when the peak reaction force value T _p is used as a standard value in the incomplete cutting determination mode is determined by the following equation (9).

T _pU = k ₃₁ · _p (9) where k ₃₁ is a constant.

For example, when the burr adhering to the steel pipe is large, or when the steel pipe is poorly positioned, it sometimes happens that the cutting cannot be performed because the bite does not hit the end face to be cut. It is this incomplete cutting determination mode that attempts to detect and improve such a state at an early stage. Therefore, for example, the reaction force is 50
If it is less than or equal to%, an alarm may be issued, so the constant k ₃₁ is set to 0.50, for example.

When the integral reaction force value and the reaction force difference value _M are standard values, the following equations (10) and (11) may be used.

_{S U = k 32 · ............... (} 10) T MU = k 33 · M ............ (11) where, k _32, k ₃₃ is a constant.

The flow of these steps is summarized in FIG.

In the above description, when the axial cutting reaction force is detected, the reaction force applied to the chucking device is used, but the present invention is not limited to this, and for example, a chamfering machine The same effect can be obtained by mounting the servo motor 7 (see FIG. 3) for controlling the position in the direction to the bolt of the mounting portion.

Further, if the load current of the servo motor 7 is detected, the same action as detecting the axial cutting reaction force can be obtained.

That is, FIG. 9 shows an example of the waveform of one cycle of the load current of the servo motor when the tip is normal. The load current A is the no-load current A _o at the cutting start time t _2.
Beginning rises from (current zero), since it maintains the peak current A _p to the cutting completion time t ₃ reaches a peak current A _p, it can be seen that the draw characteristics similar to the reaction force T of Figure 8 supra. Therefore, if the fluctuation of the peak current A _p is monitored, it is possible to grasp the bite loss condition.

Example An example of the present invention will be described below with reference to FIG. FIG. 2 is a block diagram showing an embodiment of a monitoring device according to the method of the present invention. In the figure, the same members as those in the conventional example are designated by the same reference numerals.

As shown in the figure, the base fixing bolt 11 of the chuck device 2
The load washer 10 was attached to and the nut 12 was tightened and fixed with a torque wrench. The detection signal T of the load washer 10 is amplified by the dynamic distortion amplifier 13 and input to the arithmetic unit 14 to be calculated.

Further, each set value of the defect determination mode, the wear determination mode, and the incomplete cutting determination mode is set in the arithmetic unit 14 via the setting device 15.

Further, the alarm control device 16 issues a defect alarm, a wear alarm, and an incomplete cutting alarm, and when a serious defect of defect occurs, the drive device 6 of the chamfering machine is stopped.

The outer diameter; 177.8 mmφ × thickness; 30.0 mmt When the end chamfering of the steel pipe was cut, the monitoring device configured as described above was applied.

At that time, the cutting speed of the chamfering machine was 280 rpm and the feed speed was 0.46 mm / s.

First, when the reaction force was measured for the first three, the average value of the peak reaction force was 148 kg, so the defect judgment set value was 170.2 kg, or the wear judgment set value was 155.4 kg, and the incomplete cutting set value was Was set to 74 kg via the setting device 15, respectively.

As a result, the first three could be cut smoothly, but at the fourth, the end face chip was missing and an alarm was issued.
Immediately, the chamfering machine was stopped, the end face tip was replaced, and the cutting was continued.

In addition, although the above-described embodiment has been described for a chamfering machine, the present invention is not limited to this, and it goes without saying that the present invention can be applied to, for example, thread cutting of a pipe end.

<Effects of the Invention> As described above, according to the present invention, it is possible to detect the cutting reaction force in the axial direction by a simple means, and therefore, it is possible to determine the cutting or wear of the cutting tool and the incomplete cutting at an early stage. It is possible to improve cutting efficiency and product quality, and further contribute to labor saving.

[Brief description of drawings]

FIG. 1 is a flow chart showing the steps of the present invention, FIG. 2 is a block diagram showing an embodiment of a monitoring device according to the present invention, and FIG.
Fig. 4 is a side view showing a conventional example of a chamfering machine, Fig. 4 is a side view partially showing an example of chamfering, Fig. 5 is a side view showing a state of a measurement experiment of a load washer, and Fig. 6 is a load. FIG. 7 is a characteristic diagram showing the measurement data in the washer measurement experiment.
FIG. 8 is a characteristic diagram showing the results of comparative experiments of chips, FIG. 8 is a characteristic diagram showing the transition of reaction force in one cycle of cutting, and FIG.
The figure is a characteristic diagram showing the transition of the load current of the servo motor in one cycle of cutting. 1 …… Steel pipe (steel material), 2 …… Chuck device (grasping device), 3
…… Bite, 4 …… Bite holder, 5 …… Rotary axis, 6 …… Driving device, 7 …… Servomotor, 8 …… Shank, 9 …… Chip, 1
0 …… Road washer (washer type compression strain gauge load cell), 11 …… Fixing bolt, 12 …… Nut, 13 ……
Dynamic strain amplifier, 14 …… Computing device, 15 …… Setting device, 16 …… Alarm control device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-15060 (JP, A) JP 62-166948 (JP, A) JP 49-6264 (JP, A) JP 59- 142048 (JP, A) JP-B 56-45739 (JP, B2)

Claims (1)

[Claims] 1. A device for gripping a part of a steel material to be cut by a gripping device and monitoring a cutting condition when the end surface of the steel product is cut by using a cutting tool, wherein the gripping device is fixed to a base. It is attached to the opposite bite side of the fixing bolt,
A washer-type compression strain gauge load cell that measures the axial cutting reaction force from the start to the end of cutting when steel is being cut, and the axial cutting reaction force that was measured during the first multiple cutting operations of a lot of precut steel Using the average value calculated from the peak value of, the setting device for setting the defect judgment set value, the wear judgment set value, and the incomplete cutting judgment set value, and the cutting steel material measured by the washer-type compression strain gauge load cell Input the axial cutting reaction force at the time of cutting, sequentially compare the defect judgment set value, the wear judgment set value and the incomplete cutting judgment set value set by the setting device, and determine any one of the set values. A cutting condition monitoring device for a cutting device, comprising: an arithmetic device that issues an abnormal alarm signal to an alarm control device when it is determined that the cutting condition has been exceeded.