SU1375422A1 - Electric magnetic power drive for friction welding machine - Google Patents

Description

Ucpi Ufpz if

one

R

Ca :)

h

ate

four

YU

to

Phi.1

The invention relates to welding, in particular to friction welding on machines with a power electromagnetic drive for generating axial force.

The use of a stable axial force during friction welding of dissimilar materials, especially with sharply differing thermophysical properties, does not provide high-quality welded joints.

The purpose of the invention is to improve the quality of the welded joint of dissimilar metals by applying a pulsed axial force to the parts to be welded with the possibility of adjusting its parameters.

Fig. 1 shows a block diagram of a drive of a machine for generating a pulsating axial force; in fig. 2 is a graph of voltages in the comparison device; Fig 3 is a magnetic flux diagram.

The electric power drive contains an electromagnet 1 with a power and measuring coils, a voltage regulator 2 made in the form of a thyristor switch, an integrating amplifier 3 in the circuit for determining the actual value of the magnetic flux from the signals of the measuring coils of the electromagnet and the device 4 comparing the set values of magnetic flux with its actual value in the process of welding.

Comparison device 4 is made in the form of two comparators with a Schmitt summing trigger and has a hysteresis loop (Fig. 2).

FIG. 3 is a diagram of the magnetic flux F in the core of an electromagnet, corresponding to the nature of the change in the axial force F during the welding process associated with it

F

F- 2tso5

where f is the magnetic flux;

| Lo - magnetic permeability; S is the surface of the electromagnet pole. When the electromagnetic power drive is turned on, a single output signal of the comparator device (Fig. 2) unlocks the thyristor key (Fig. 1) and the supply voltage Uc goes to the power coil of the electromagnet 1, in which a transient process of current and, consequently, flow, corresponding to the section AB, (Fig. 3). In the process of increasing the magnetic flux in the measuring coils of the electromagnet 1, an emf is induced proportional to the change in the magnetic flux.

e w

M) dt

(2)

where W is the number of turns of the measuring coils.

The EMF is fed to the input of an integrating amplifier, the incoming signal of which Yf is proportional to the actual value of the magnetic flux Φ during the welding process.

The signal Ua is supplied to the comparison device, which compares the actual magnitude of the magnetic flux Φ with the given values of UV 1 and IF2, which determine the maximum and minimum values of the pulsating magnetic flux. If the IF and IF are equal, the comparison device switches, its output signal takes a zero value and locks the thyristor key. The transient process of the decrease of the magnetic flux (the section of the aircraft,

5 of FIG. 3). When the magnetic flux decreases to the value F2 determined by the driving voltage UV 2, the comparator switches and switches back to the unit state, the thyristor switch turns on and the magnetic field increases.

 flow to the value determined by my UV i. The process then repeats.

By varying the values of the setting voltages UV 1 and IF 2, it is possible to control within wide limits 5 both the average value of the axial force determined by the flow Fsr and the amplitude of the pulsations of the axial force determined according to (1) by the values of the flows F I and F 2.

The period of pulsations can be estimated by solving the differential equation of the transition process of the rise (section A | B, Fig. 3) and the decay (BC) of the magnetic flux in the core of the electromagnet. For site AiB

 - 1- b, -,

(3)

0

five

where is l

inductance of the power coil of an electromagnet; g - active resistance; Uc is the voltage applied to the coil;

i - the current value of the current of the power coil corresponding to the magnetic flux.

Having solved equation (3) in time, the current changes from i2 to ii (corresponding to the change in flux from Ф2 to Ф i),

I

50

 Кф - К.1 + 1

bl Tln-5 ;; | ,

(four)

constant time of the power coil of the electromagnet;

feed voltage forcing factor;

ripple factor.

For the aircraft section, the magnetic flux decay transition equation

Lf + ri 0.

Solving equation (5) over the time of the current change gives the value

ti2 t1n (1 + Kn). The total period of pulsations Tn is equal to

T .. t2l + t | 2 Tin (

TO..

to -1

, + 1). (7)

and you

1 o

 id} 1 Fi5.2

From formula (7) It follows that to obtain the required pulsation period, it is necessary at the design stage of a power electromagnet to set a constant time T of the power coil and the degree of force K of the supply voltage.

The use of a friction welding machine allows to increase the quality of welded joints due to the intensification of heat release during welding with pulsating axial force and to ensure the welding of dissimilar materials with drastically different thermal physical properties.

F f

Fsr

2

i

x

Fig

Claims (1)

ELECTROMAGNETIC POWER DRIVE OF A FRICTION WELDING MACHINE, including an electromagnet with power and measuring coils mounted on a fixed magnetic circuit of an electromagnet, a voltage regulator for supplying a power coil of an electromagnet, a device for comparing a given magnitude of the magnetic flux with its actual value during axial movement, and an integrator, characterized in , what. in order to improve the quality of welded joints of dissimilar metals by creating the possibility of controlling the parameters of the pulsating axial force, it contains an additional reference input in the comparison device, the output of which is connected to the control input of the voltage regulator, made in the form of a key, while the comparison device is made in the form of two comparators with Schmitt summing trigger, the inputs of which form an additional master input of the comparison device. FIG. 1 SU 1375422 A1