JPS6156079B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a rotary flying shear, which is a type of cutting machine used to continuously cut objects such as pipes to predetermined dimensions.

B. Summary of the Invention The present invention provides a rotary flying shear in which an acceleration/deceleration torque that changes linearly from a negative value to a positive value is applied to the prime mover from just before cutting until the end of cutting to maintain a constant horizontal speed of the blade during cutting. By doing so, the life of the cutting blade is extended.

C. PRIOR ART FIG. 1 is a schematic configuration diagram of a general rotary flying shear, in which 1 is a prime mover, 2 is a gear, 3 is an object to be cut (for example, a pipe), A is a standby position of a cutting blade (not shown), B is the cutting start position, C is the deepest position of the blade, D is the position where the blade exits after cutting,
O is the rotation center position of the cutting blade, and Vo is the conveyance speed of the object 3 to be cut.

When the cutting position approaches, the prime mover 1 receives a cutting command.
starts and rapidly accelerates the cutting blade that was waiting at point A, and sets the circumferential speed of the cutting blade to V before reaching point B, where cutting begins. V is maintained until the cutting is completed and the cutting blade comes out of the object 3 at point D, and then it is rapidly decelerated and stopped at point A to wait for the next cutting command.

Figure 7 shows a general prime mover 1 that includes the drive of the cutting blade.
This figure shows a control device for a direct current machine.For example, the control device for this prime mover 1 is disclosed in
There are devices disclosed in Japanese Patent Application Laid-open No. 49-9617, and Japanese Utility Model Application Publication No. 49-77225. The control device shown in FIG. 7 will be described below.The adder in the speed control device 4b
At AD ₁ , the speed setting signal and the tachogenerator
After determining the deviation from the speed detection signal of the prime mover 1 detected by the TG and amplifying the deviation in the speed control circuit ASR, the adder in the acceleration/deceleration torque control device 4
At AD ₂ , it is compared with the armature current of the DC motor, which is the prime mover 1, detected via the current detector CT. The deviation signal of the comparison result is the current control circuit.
It is sent to the phase control circuit PH through ACR and changed into a phase signal corresponding to the deviation signal from AD ₂ .
Supplied to the gate of the thyristor of the converter CON. Therefore, the converter CON supplies a DC output corresponding to the phase signal to the prime mover 1 to control it. Here, the torque T of the DC motor that is the prime mover 1 is T
=KφIa (where K is a constant, φ is the field flux, and Ia is the armature current), and it is well known that it is proportional to the DC armature current Ia, which is generally used as the prime mover of industrial machinery.

By the way, in a flying shear, working force, frictional force,
The inertial force changes from moment to moment, and the torque of the prime mover 1 is controlled in order to respond to such load fluctuations. At this time, the load changes in the acceleration/deceleration torque control device 4, and the armature current of the motor changes. A change in is detected by the current detector CT. This detection signal is applied to adder AD ₂ to find the difference from the speed deviation signal, and the converter CON is phase controlled according to the difference signal to adjust the armature current and keep the motor torque constant. This is controlled as follows, and corresponds to torque changes such as when the cutting blade cuts into the blade 3 to be cut.

D Problems to be Solved by the Invention In Figure 1, an arbitrary position of the cutting blade during cutting is E, and the circumferential speed of the cutting blade at point E is V.
_T , the horizontal velocity is V _H , and the angle between vectors V _T and V _H is α. V _H = V _T cos α, V _H = V ₀ cos θ at points B and C, and α = 0 at point C, so V _H = V ₀ , and the horizontal speed of the cutting blade V _H and the object to be cut. It is only at point C that the conveying speed V ₀ of the cutting blade matches the conveying speed V 0 , and before and after that, the horizontal speed V _H of the cutting blade is decelerated in proportion to cos α. In this way, a relative speed difference occurs between the cutting blade and the object to be cut during cutting, which causes undue stress on the cutting blade and shortens its life. That is, the reason why such a problem occurs is that the speed of the prime mover 1 is made to correspond to the speed of the object to be cut, and the torque of the prime mover 1 is controlled to be constant.

Therefore, it is an object of the present invention to provide a device of this type that is simple and can extend the life of the cutting blade.

E. Means for Solving the Problems In order to solve the above problems, it is sufficient to make the horizontal speed V _H of the cutting blade coincide with the transport speed V ₀ of the object to be cut, at least during cutting. V _H =
If the circumferential speed of the cutting blade when maintained at V ₀ is V, then V ₀ =Vcosα, so it is sufficient to set V=V ₀ /cosα. For this purpose, a prime mover that drives a blade for cutting the object to be cut, an acceleration torque control device that makes the speed of the prime mover uniform, and a signal that controls the speed of the prime mover according to the conveyance speed of the object to be cut. In order to apply acceleration/deceleration torque to the prime mover to keep the horizontal speed of the cutting blade constant, the rotational speed of the prime mover is set to V 0 and the conveyance speed of the object to be cut is set to V ₀ . When, during the cutting, V ₀ /
A signal generator that generates a signal that linearly changes from a negative value (-I ₀ ) to a positive value (+I ₀ ) so as to have a parabolic change approximating cosα, and a signal generated by this signal generator. an adder that adds the output and the signal output obtained by the speed control device; and controlling the acceleration/deceleration torque control device with the addition output of the adder;
Acceleration/deceleration torque is applied to the prime mover.

F Action Applying a deceleration torque of -I ₀ at point B, zero acceleration torque at point C, and an acceleration torque of +I ₀ at point D, that is, acceleration/deceleration torque from point B to point D shown in Figure 3, to the prime mover 1. Therefore, the horizontal speed V _H of the cutting blade is approximately the conveyance speed of the workpiece from point B where cutting starts to point D where cutting is completed and the cutting blade exits.
V equals ₀ .

G. Embodiment FIG. 4 is a block diagram showing an embodiment of the present invention, in which the same reference numerals as in FIG. 7 indicate the same parts that perform the same operations. That is, 4 is an acceleration/deceleration torque control device for making the speed of the prime mover 1 uniform, and this control device 4 controls the conveyance speed of the object 3 to be cut.
A signal e ₀ ′ obtained through a control device 4b that controls the speed according to V ₀ and an output e ₃ of a signal generator 5, which will be described later, are inputted via an adder 4a, and the sum signal (e ₀ ′+e ₃ ) is sent to the prime mover 1. 5 is a signal generator that generates a signal similar to the waveform shown in FIG. 3; an arithmetic unit 6 that squares a signal _e0 corresponding to the circumferential speed V of the cutting blade;
The integrator 7 integrates the output of the calculator 6 via the switch _S1 , which is closed only while the cutting blade is between BCD in _FIG . A level adjuster 8 that generates a level signal _e2 that is half the maximum value of the output _e1 , and a subtracter 9 that generates a signal obtained by subtracting the output _e2 of the level adjuster 8 from the output _e1 of the integrator 7. , and a switch _S2 interlocked with the switch _S1 , and the output _e3 of the subtracter 9 is applied to the adder 4a on the input side of the acceleration/deceleration torque control device 4 via the switch _S2 .

As mentioned above, the signal generator 5 generates the waveform shown in FIG. 3, and its operation will now be explained. That is,
The characteristic of the output e ₁ of the integrator 7 is as shown in Figure 5a, and since e ₃ is e ₁ - e ₂ , the characteristic shown in Figure 5 a can be directly changed to its maximum value in the negative direction. Only 1/2 has been migrated. That is, e ₃ becomes as shown in FIG. 3b, which is the same as the shape shown in FIG.

Further, for example, if the transport speed of the object to be cut is 1/2V ₀ , the slope rate of e ₁ will be 1/4 of that in FIG. 5a, and the time required for cutting between BCD will be doubled. Also, e ₂
Since the amount of is also halved, the respective characteristics of e ₁ and e ₃ become as shown in Figure 6 a and b.

Next, the operation of the present invention will be explained.

Assuming that the speed of the object to be cut is V ₀ , in order to cut the object to a fixed size, the horizontal speed of the cutting blade must also be rotated at a speed synchronized with this V ₀ . To do this, the circumferential speed of the cutting blade should be set to V (=V ₀ /cosα) shown in Fig. 2, and therefore, the torque control command supplied to the prime mover 1 should be a signal e corresponding to this V. FIG. 4 shows a circuit for producing this signal e. In the figure, e ₀ is a command value (setting value) corresponding to the circumferential velocity V of the cutting blade immediately before time t ₂ (position B point) shown in FIG.

When the prime mover 1 is stopped with the cutting blade positioned at point A, when the tip of the object 3 to be cut reaches a predetermined position, a start command is issued and the set value e ₀ is set to the control device 4.
b, and this control device 4b emits a signal e ₀ ' corresponding to e ₀ . The control device 4b is generally composed of an amplifier or the like, but for convenience of explanation, one with an amplification degree of "1" is used here, and e ₀ =e ₀ ' is applied to the adder 4a. At this point, the position of the cutting blade is at point A (time
t ₀ ), the signal from the signal generator 5 is not applied to the adder 4a, and therefore the adder 4a outputs only the signal e ₀ ' to the acceleration/deceleration torque control device 4. The acceleration/deceleration torque control device 4 converts the input signal e ₀ ' into a control signal e suitable for the input signal e 0 ', but if the prime mover 1 is, for example, a DC machine,
This torque control device 4 outputs a control signal e for controlling the armature current or field current of the DC machine, and the prime mover 1 is driven with a torque corresponding to the setting signal _e0 . For this reason, prime mover 1
_The cutting blade _{connected to}
Immediately before (between t ₁ and t ₂ ), the circumferential speed corresponding to the set value e ₀ is reached, but the torque is controlled by the acceleration/deceleration torque control device 4 as shown in FIG. From the start until time _t2 , the torque is constant as shown by the dotted line in Fig. 2.

On the other hand, e ₀ is also applied to the arithmetic unit 6 and squared, and is also applied to the level adjuster 8 to adjust the level. However, since the switches S ₁ and S ₂ are in the open state, The output e ₃ of the signal generator 5 is zero.

Next, the cutting blade moves to time t ₂ (position B) shown in Figure 2.
When this is reached, the detector detects this and closes the switches S ₁ and S ₂ . For this reason, the arithmetic unit 6
The output of is integrated by an integrator 7 as shown in FIG. 5a, and its output e ₁ is applied to a subtracter 9.
Since the signal e ₂ adjusted to 1/2 of the maximum value of e ₁ is applied to the subtracter 9 before the level adjuster 8, the subtraction of e ₁ - e ₂ is performed in this subtracter 9. As a result, an output waveform _e3 that changes linearly from negative to positive as shown in FIG. 5b is obtained and output to the adder 4a. Therefore, the adder 4a calculates e ₀ '+e ₃ and inputs it to the acceleration/deceleration torque control device 4.
First, at time _t2 , the addition of the negative signal _e3 causes the acceleration/deceleration torque control device 4 to generate a signal e in the direction of greatly reducing the torque, that is, in the direction of significantly reducing the armature current. In order to issue a command, its torque characteristic decreases significantly at time t ₂ in proportion to e ₃ as shown by the dotted line in FIG. As the torque decreases, the rotational speed of the prime mover 1 also decreases, so the circumferential speed of the cutting blade also decreases, and this decrease command continues until time _t3 , but at time _t3 , e ₀ ′ + e ₃ = e ₀ ′, and the circumferential velocity is also equal to V ₀ . After time t ₃ , e ₃ is added to e ₀ ′.
Since the polarity is positive, it is input as an acceleration torque command to the acceleration/deceleration torque control device 4, and the torque of the prime mover 1 increases from the time of the command e ₀ ', and the circumferential speed is also increased. In this way, in the acceleration/deceleration torque control device 4, the control signal based on e ₀ '+e ₃ , that is, the circumferential speed V of the cutting blade shown in FIG. 2 changes from time t ₂ to t ₄
The torque control signal e for the prime mover 1 is generated so as to have a parabolic change approximating V ₀ /cosα within the range of V 0 /cosα.

When time t ₄ arrives and the cutting blade is at point D, the detector detects this and opens switches S ₁ and S ₂ , making the circumferential speed dependent only on the set value e ₀ .
At time _t5 , a stop command is given to the prime mover 1.
As a result, the circumferential speed of the cutting blade rapidly decreases, and at time _t6 , the cutting blade stops at point A to prepare for the next cutting operation.

Note that the signal generator 5 may have various configurations other than the one shown in FIG. For example, one that generates a signal that changes linearly from negative to positive during cutting.

In addition, in this embodiment, the cutting completion point is the first point.
We have explained the case where the speed is set at point D in the figure and the speed at point B and point D should be the same, but there are cases where the speed at point D does not necessarily have to be exactly the same as point B, and Even if the speed increases after passing the point, there may be no problem, so in that sense, the maximum values of positive and negative torques do not need to match each other.

H. Effects of the Invention As explained above, according to the present invention, acceleration/deceleration torque that linearly changes from negative to positive is applied to the driving motor of the cutting blade during cutting. The horizontal speed of the inner blade becomes constant, there is no difference in relative speed to the object to be cut, and the possibility of damage to the blade due to excessive stress is significantly reduced. In other words, the life of the cutting blade can be extended. In addition, the signal generator, which is a means of extending the life of the cutting blade, simply needs to generate a signal that changes linearly from negative to positive, so its configuration is simpler than a curved function generator. It is inexpensive, and has various excellent effects such as a simple configuration that only supplies a linear signal to the control system of the prime mover.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a general rotary flying shear, Figs. 2 and 3 are graphs for explaining the present invention, Fig. 4 is a block diagram showing an embodiment of the present invention, and Fig. 5 a ,b and Figure 6a,
7b is a graph for explaining the operation, and FIG. 7 is a block diagram showing a conventional motor control device. 1... Prime mover, 4... Acceleration/deceleration torque control device,
4a... Adder, 4b... Speed control device, 5...
signal generator.

Claims (1)

[Claims] 1. A prime mover that drives a blade for cutting the object to be cut, an acceleration/deceleration torque control device that makes the speed of this prime mover uniform, and a horizontal speed of the blade at the time of starting cutting to match the transport speed of the object to be cut. and a speed control device that controls the rotational speed of the prime mover and the conveyance speed of the object to be cut by applying acceleration/deceleration torque to the prime mover to keep the horizontal speed of the cutting blade constant.
, a signal generator that generates a signal that changes linearly from negative to positive so that it changes in a parabolic manner approximating Vo/cosα during cutting, and a signal output generated by this signal generator. and a signal output obtained from the speed control device, and an adder that adds the added output to the acceleration/deceleration torque control device.