JPS6247611B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in electromagnetic forming equipment.

In electromagnetic forming, an impact current is supplied from an impact capacitor to a forming coil inserted into or outside the pipe to be formed, generating a changing magnetic field and an induced current flowing through the pipe to be formed, and applying electromagnetic force to expand or narrow the pipe. Although this method performs molding, the amount of molding varies depending on the state of bonding between the coil and the object to be molded, and when the degree of bonding is small, a large amount of energy is applied, resulting in damage to the coil.

The present invention detects the inductance of the coil set on the object to be formed, determines the state of connection with the object to be formed, and thereby controls the interruption of the impact power supplied to the coil.

The present invention will be explained below with reference to an embodiment of the drawings.
In FIG. 1, reference numeral 1 denotes a pipe to be expanded and formed, the end of which is inserted and held in a mold or the mold surface of a crimp base material 2, and is pressed against the mold surface by applying electromagnetic force from the inside. 3 is a molded coil inserted into the pipe 1, 4 is a power supply device, 5 is a capacitor, and 6 is a discharge switch. In the molding process, the capacitor 5 charged to a predetermined voltage is discharged by closing the start switch 6, and an impulse current is passed through the molding coil 3 to generate a changing magnetic field. A force is applied to expand the pipe 1 and press-form it into the mold 2.

7 is the coil 3 inserted into the pipe 1 to be formed.
This is a discrimination control circuit that detects and discriminates the inductance, that is, impedance. The degree of connection between the forming coil 3 and the pipe to be formed 1 in the inserted and set state,
That is, the inductance of the coil 3 changes depending on the degree of proximity, and when there is a gap and the degree of coupling is small, the inductance is small, and on the other hand, when the degree of coupling is large, the inductance becomes large. This is determined by the circuit 7, and if the detected impedance is smaller than a certain value, the charging switch 8 is turned off by the determined output. That is, circuit 7
The output is "1" if the impedance is higher than the reference value, and "0" if it is below the reference value. 9 is a discrimination circuit that discriminates the charge voltage of the capacitor 5. If it is lower than the reference value, it will be "1", and if it reaches the reference value, it will be "0".
Outputs the discrimination output. 10 is a discrimination circuit that checks the resistance between the circuit connecting the forming coil 3 and the power source, and outputs a signal "1" if the resistance is lower than the standard value, and outputs a signal "0" if the resistance value increases due to coil breakage, etc. . Reference numeral 11 denotes an AND gate, which applies AND outputs of the outputs of the respective discrimination circuits to the switch 8 for control.

Figure 2 shows a circuit that detects the impedance of the forming coil.The inductance of the coil changes depending on how it is inserted into the pipe to be formed, and the line capacitance,
Since the winding resistance is almost constant, a signal proportional to the change in inductance is detected by impedance detection. The circuit is an example using the resonance method, in which a variable frequency power supply e is connected in series to the measured impedance Zx = Rx + jXx of the coil 3, and the impedance Zx
Connect the short circuit switch S. First, the frequency is changed with the impedance to be measured Xx short-circuited by the switch S, and the resonance frequency f ₁ and the half-value width Δf ₁ of the frequency are determined. Next, the switch S is turned off, the impedance to be measured Xx is inserted, and the resonance frequency f ₂ and the half width △f ₂ are determined. Rx and Xx are given by the following equations.

Rx=1/WC(△ ^f2 / ^f2- △ ^f1 / ^f1 ) Xx=1
/WC(f ₁ − f ₂ ) Therefore, this makes the impedance of the coil
Zx can be detected and the detection signal can be determined. The discrimination circuit 7 also includes the detection circuit shown in FIG.

Of course, various methods can be used to measure the inductance and impedance of the coil 3. For example, there are some that utilize phase differences caused by energization.

If the degree of coupling between the coil 3 and the pipe to be formed 1 is small and the detected impedance is small and smaller than the discrimination criterion, the discrimination circuit 7 outputs "0".
is applied to the AND gate 11, and the capacitor charging switch 8 is turned off. This prevents the coil 3 from being damaged by applying large amounts of energy.
Also, if the coupling degree of the coil is large and the impedance is high, the discrimination output of the circuit 7 becomes "1", and if the resistance discrimination circuit 10 provided as necessary also outputs a signal "1" if the coil circuit is normal, A signal is applied to the switch 8 from the AND gate 11 and the switch is turned on to charge the capacitor 5. The charging voltage is constantly monitored by the discriminating circuit 9, and when the charging voltage reaches a standard value, the half circuit 9 sets the signal to "0", so the switch 8 is turned off to prevent higher energy charging than required. Charging energy is supplied to the coil 3 by activation of the discharge switch 6 to perform magnetic forming, but a constant and controlled energy is supplied every time, allowing accurate electromagnetic forming to be performed, and the coil 3 to be formed into the object 1. When the degree of coupling is small, charging of impact energy is controlled so that safe molding can be performed.

For example, when forming is performed by repeatedly acting on one pipe 1 to be formed, even if the degree of coupling of the coil 3 is high at the beginning, the pipe 1 expands and forms during the repeated processing. As the processing progresses, the gap with the coil 3 increases and the degree of coupling decreases, but the impedance also decreases corresponding to this degree of coupling. Therefore, this change is judged by the judgment circuit 7, and when it is less than the standard value, the judgment signal is used to turn on the switch 8.
If the charging is stopped by turning off the charging, the amount of the molded product can be stopped at a predetermined point, and safe processing can be performed.

If the discrimination circuit 7 discriminates the detection signal in stages, controls the charging switch 8 in stages, and controls the charging of the capacitor 5 according to the discrimination signal, the energy supplied to the coil 3 can be controlled and stabilized according to the processing state. It is also possible to perform magnetic molding processing.

The same applies when the forming coil is placed outside the pipe to be formed and drawing forming is performed. Extremely stable electromagnetic forming can be achieved by determining the degree of bond between the forming coil and the material to be formed and controlling the energy. can. In order to detect and discriminate the inductance and impedance of the coil, which change depending on the degree of bonding between the forming coil and the material to be formed, various configurations other than the above-described embodiments and conventionally known devices can be used.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a circuit diagram of a part thereof. 1 is a pipe to be formed, 3 is a forming coil, 4 is a power source, 5 is a capacitor, 6 is a discharge switch, 8 is a charging switch, 7 is a coil impedance detection/discrimination circuit, and Zx is coil impedance.

Claims (1)

[Claims] 1. A molding coil is provided inside or outside of the molded object, an impact capacitor is connected to the molding coil, and the discharge of the capacitor causes an impact current to flow through the electrostatic molding coil to mold the molded object by electromagnetic force. a first half-circuit for detecting and determining whether the inductance or impedance of the molding coil set on the molded object is below a set reference value; and a second discrimination circuit for detecting and discriminating, and a control circuit for controlling the charging switch of the power supply device for the shock capacitor to be cut off based on the discrimination signal of the first or second discrimination circuit. Electromagnetic forming equipment.