RU2424882C1 - Multielectrode device for contact welding of mesh reinforcement - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to multilelectrode device for contact welding of mesh reinforcement. Top stationary crossarm 7 supports welding transformer 1. At least one welding circuit comprises electrodes 10, moving and stationary bars 5 and 6. Every of n transformers 10 is connected with secondary of welding transformer a via n thyristor terminals 8 secured on stationary bar 6 and connected via one-pin connector assembly with n-channel control unit 3 for consecutive welding at each point. Electrodes 10 with flexible elements 11 are secured on top stationary crossarm 7 and connected via its ducts and flexible current conductors 9 with thyristor terminals 13. Bottom crossarm 14 with second bar 5 of welding circuit may displace. Crossarm 14 is hinged to rods 21 and cams 20 fitted on shaft 19 with electric coupling 18 and retainer 46 that allow locking at dead centers. Both crossarms are jointed by rectangular guides 25 with their upper parts are closed by bare conductors 26 with replaceable gaskets 27 and pressure gage.

EFFECT: reduced consumed power, higher welding quality and efficiency.

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Description

The invention relates to the field of spot welding and can be used in the manufacture of reinforcing mesh.

The book (Kochergin N.A. Contact welding. L .: Mash., 1987) describes the fundamentals of the theory and technology of all methods of contact welding from the practical side.

All the time it was believed that the decisive factor in welding is only the electrical heating of the parts. In fact, electric heating is a necessary condition, but not yet sufficient. The sufficiency condition determines the program for applying mechanical pressures. For modern contact machines, it is very poor, primitive and completely in harmony with the flexibility of electrical systems of machines.

Machine designers are mainly interested only in the magnitude of the compression force, and not in the program of their application. The current technological recommendations are insufficient and uncertain, since they do not speak of the recommended pressure application program. This uncertainty is the main reasons for the instability of the quality of welded joints

The disadvantages of this method include the fact that no point machine applies the pressure of the electrodes - slowly, statically. Pressure is applied, of course, and in all cases, shock, variable in compression force and in the time this force acts (see Kochergin N.A. Contact welding. L .: Mash., 1987, p. 55).

The designers' clear desire for high performance, having sacrificed the capabilities of static electrode compression, retains large peak network loads, high compressed air consumption (Automated line for the production of welded wire mesh LTS-1500R2. There is still a belief that current shunting in spot welding is a complex and it is physically impossible to fight it (see Kochergin N.A. Contact welding. L .: Mash., 1987, p. 74).

A multi-electrode device for resistance welding of a reinforcing mesh is known. including a welding transformer, an electrode displacement drive, a control unit, each of n electrodes being connected to the secondary winding of the welding transformer through n thyristor contactors connected to an n channel control unit to ensure sequential welding of each point, while the electrodes are connected by a common displacement drive (RF Patent No. 2129481).

The device provides a “cold” contact of all the points to be welded before turning on the electric current, and bypassing of the welded points is excluded, which allowed sequential welding of all points with the same current value with high quality.

The disadvantage of this device can be considered low productivity and violation of electrical cold contact due to the skew of the movable beam, due to the lack of stops, which sits during the downward movement of the movable beam.

The insufficient pneumatic drive force exerted by the cylinders mounted on the edges of the movable crosshead limits the number of simultaneously compressible electrodes.

Also known is a resistance spot welding machine with a mechanical drive of a movable crosshead according to the type of guillotine shears operating in the continuous mode “Masonry Mesh Welding Machine (MAX)” (see KIT-Komplekt website - www.kit-complect.ru / catalog2 / from May 25, 2009)

Long-running spring loaded electrodes with a long stroke are in contact with the transverse rod long before the bottom dead center, the welding current is switched on, and the future contact is cleaned from oxides and contaminants by reflow. The continuous movement of the traverse reaches a dead point, providing maximum compression for a moment and on the return stroke upward, an alternating, decreasing pressure completes the forging.

The disadvantages of the device include the fact that short-term contact compression, increasing to the maximum and decreasing to zero, does not allow the full use of the energy of mechanical activation of the contact, welding transformers in peak mode consume a lot of power from the network, fulfilling the condition of ensuring high quality of the melting method.

The objective of the invention is to reduce power consumption and increase productivity by alternately turning on the welding circuits, investing in the weld contact of mechanical shear energy, excluding inrush currents; ensuring welding as soon as possible by turning on the welding current of considerable strength and providing control over the welding process; improving the quality of welding due to the harmonization of the software application of mechanical energy and welding current, excluding the fusion of contacts with the formation of fireworks of molten spatter, which significantly increases the resistance of electrodes, reduced metal consumption and increased environmental friendliness of the installation.

The problem is solved due to the fact that the welding is carried out by simultaneously applying to all the welded points of static sedimentary pressure, the shutter speed, the duration of which depends on the number of welded points, and sequential supply to the contact zone of each welded point of the welding current, disconnected by the feedback signal, at this is carried out alternately welding in the installed circuits. Welding is carried out in a multi-electrode device for contact welding of a reinforcing mesh, characterized in that it includes one welding transformer mounted in the center of the upper fixed beam, a control unit, at least one welding circuit containing electrodes, a movable and fixed rod, each of n electrodes connected to the secondary winding of the welding transformer through n thyristor contactors mounted on a fixed rod and connected via single-pin connectors with n channels a control unit to ensure sequential welding of each point, and the electrodes mounted on the upper fixed crosshead provided with elastic elements are communicated through the crosshead channels by flexible conductors with thyristor contactors, and the lower crosshead with the second welding circuit rod located on it is movable and connected by ball bearings with connecting rods and eccentrics mounted on the drive shaft, with an electrofusion coupling and a latch that ensures stopping at dead points, in addition, under the movable and fixed traverses are connected by rectangular guides, the upper parts of which are closed by the cantilevers equipped with interchangeable gaskets and a pressure gauge, and the traverses have a honeycomb structure and are made of multilayer plywood sets.

Distinctive features of the proposed device is:

- the implementation of several welding circuits operating alternately, which provides the opportunity to increase productivity while reducing power consumption and non-ferrous metal consumption;

- the presence in the device of an electromagnetic clutch and a latch to ensure fixed stops of the movable yoke at the dead points in order to ensure the repeatability of a given compression in each cycle;

- installation of a welding transformer directly in the center of the fixed beam of a honeycomb structure to reduce the geometric dimensions of the welding circuit, flexible conductors and reduce inductance; improving the convenience of circuit maintenance;

- the presence of interchangeable gaskets and a pressure meter to adjust the force of squeezing the electrodes between the traverses;

- the implementation of the movable lower beam so that when it is positioned below it is possible mechanized loading of the transverse rods;

- the manufacture of a movable and stationary traverse from dielectrics, for example, from sets of multilayer plywood, which reduces magnetic fields, reduces metal consumption, improves the environmental friendliness of the welding process;

- introduction of single-contact connectors in the control circuit of thyristor contactors, which will allow you to change the size of the transverse cells of the welded grid.

In the proposed device, each contact is sequentially welded, and the process parameters are monitored in real time, the welding current is switched off by feedback at the moment of welding completion, and the welding itself is performed as soon as possible, but with a significant current strength to improve the quality of welding. The analog-to-digital converter digitizes the resistance and welding current parameters that change during the heating process, which are transmitted to the controller, are processed and a signal is issued to close the thyristor contactor, i.e. switching to welding of the next contact occurs. Given that the impedance of the butt contact decreases approximately linearly from the initial value in the cold state to zero at the moment of compression and welding during the formation of the molten core, when R = 0. (see Kochergin N.A. Contact welding. L .: Mash, 1987, p. 83).

The force of compression of the electrodes is regulated by gaskets, and is adjusted by a pressure meter.

The proposed device allows you to apply static sedimentary pressure while holding the traverse in the upper position, the duration of which depends on the number of welded points, remove and squeeze out all the oxides and contaminants from the welded contact zone with the creation of a high specific pressure to obtain mechanical activation of the contact and cold electrical contact of all welded points at the same time to exclude bypass welding current.

Activation of the contact by mechanical compression transforms into quiet heating of a tight contact without molten spatter by the resistance method with the sequential application of a welding current to each of the electrodes.

The invention is illustrated in the drawing, where Fig. 1 is an electrical diagram, Fig. 2 is a layout diagram of a device, and Fig. 3 is a perspective view of a device.

The device includes a transformer 1 connected to a 380 V network, the primary winding of which is switched on by a thyristor contactor 2 using a control unit 3, the secondary winding of the transformer 1 is connected via m flexible conductors 4 to m hard conductive rods 5 and 6, cooled by water. On the rod 6, through insulators mounted on a fixed traverse 7, there are n thyristor contactors 8 connected by flexible conductors 9 to the electrodes 10. Each electrode 10 is equipped with an elastic element 11 to provide a controlled clamping force.

To protect the thyristor contactors 8 from breakdown, a shunt 12 is installed in the secondary circuit. Thyristor contactors 8 connected to the secondary winding of the transformer 1 are connected to the control unit 3 through n outputs m of rigid current-carrying rods 6 and mounted on the upper stationary cross-beam 7. Each pair of rods 5 and 6 forms a welding circuit, and all m circuits are connected to the secondary winding via thyristor contactors 13 in such a way that only one of them can operate at a time. The activation of the circuits is controlled by block 3. The device may contain several (m) welding circuits.

Current-carrying rods 5 are fixed in the plane of the electrodes of their welding circuit on the movable traverse 14.

The device (figure 2) includes a mechanical drive with a flywheel 15, an electric motor 16, a gearbox 17, an electrofusion coupling 18 and a latch 46 that controls stopping at a given point by a signal from position sensors 44 and 45. Shaft 19 with eccentrics 20, connecting rods 21 and ball bearings 22 rotates in rolling bearings 23 installed in the frame 24.

Rectangular guides 25 close the height-adjustable ogolovniki 26, which determine the closed height between the movable traverse 14 and the stationary 7 using interchangeable gaskets 27 to adjust the compression force.

A movable beam 14 moves along four rectangular guides 25 of the bed 24, textolite inserts are installed in the rectangular grooves of the beam 14, providing a low coefficient of friction. In the upper part of the guides 25, with the help of head brackets 26 and interchangeable gaskets 27, a cross-beam 7 of a honeycomb design with holes for installing electrodes 10, equipped with elastic elements 11 and connected by a flexible current lead 9 with thyristor contactors 8 mounted on rigid current-carrying rods 6. is fixed and fixed. control 28 mounted on the rails 25 is connected to the motor 16 by a welding transformer 1, a control unit 3.

Auxiliary mechanisms of the device are located in three tiers.

Lower - mechanized installation of transverse rods loading trolley 31.

Medium — feed of longitudinal rods along guides 30 and mesh welding zone.

Upper - the movement of the welded mesh 42.

The longitudinal rods 29 are fed into the weld zone along the guides 30. The transverse rod is fed into the weld zone by a trolley 31 with tool holders 32 along the guides 33. The welded wire conveyor 42 moves in guides 34, is controlled by position sensors 35 and 36, and is driven by a gear motor ( not shown) through the rocker mechanism 37. The welded transverse wire 38 is gripped by hooks 39. The current-carrying rods 5 are equipped with fork clamps 40. For cooling the rods and welding transformer 1, the cooling system 41,

The welded mesh is moved using the device 42.

The size of the transverse mesh cells is changed by turning on / off the single-contact connectors 43 of the control circuit.

The 28 control panel is equipped with the ability to manually configure each mechanism and the automatic operation system.

Given that the contact resistance drops approximately linearly from the initial value in the cold state to zero at the time of compression and welding, when a molten core is formed, when R = 0, to switch to the next contact after receiving the molten core in the previous one, to control unit 3 a standard controller with a measurement frequency of 1 ms and an analog-to-digital converter are installed. The resistance and welding current parameters are being changed in real time. The controller calculates the changing parameters and, upon reaching the molten core, gives the command to switch to the next contact, providing high-quality welding if rust or inclusions that impair electrical conductivity get into the contact. To ensure cold electrical contact of all welded points, it is possible to adjust the closed height between the movable and stationary traverses by changing the stationary position by installing special gaskets 27. A pressure meter is installed for monitoring.

The device operates as follows.

Transverse rods 38 are laid on the lodgements 32 of the loading trolley 31. The trolley is fed all the way to the welding zone along the guides 33 above the current-carrying rods 5 equipped with fork position locks 40. By turning the handle, the operator opens the lodgements 32 and drops the transverse rods onto the clamps 40. Rolls out the trolley. On command from the control panel 28, the electric motor 16 of the mechanical drive is turned on, the cooling system 41 of the welding transformer 1 and the current-carrying rods 5 and 6.

According to the "automatic cycle" signal from the remote control 28, the control unit 3 gives a command to the electrofusion coupling 18 and the latch 45, providing rotation of the shaft 19 with the eccentrics 20, on which the connecting rods 21 are mounted, through the ball bearings 22 connected to the movable traverse 14 to the top dead center to the position sensor 44. During soaking of all points under static sedimentary pressure, all oxides and contaminants are extruded, contacts are mechanically activated, and all points are cold-contacted before electric current is applied. At the command of the sensor 44, block 3 turns on the welding transformer 1 and sequentially welds all n points in all m welding circuits connected to the secondary winding of the welding transformer 1. The exposure time is determined by the number of contacts. Electric heating of tight contacts is carried out as short as possible, but with a significant current strength, which is ensured by welding one point at a given moment.

After welding, at the command of block 3 of the electrical coupling 18 and the latch 46 lower the movable beam 14 to the signal of the position sensor 45. The control unit 3 includes a gear motor (not shown), which moves the trolley 42, connected with the link 37, forward along the guides 34 to the position sensor 36. The first welded transverse bar grips the hooks 39 and moves it back to the command of the position sensor 35. During welding, the operator loaded the transverse rods 38 into the trolley 31, rolls it along the guides 33 all the way into the welding zone above the current-carrying rods 5 and drops it onto the fork position locks 40. It rolls the trolley 31 back to the stop to the loading hopper (not shown) and gives a command to the next welding cycle.

Claims (1)

A multi-electrode device for contact welding of reinforcing mesh, characterized in that it includes one welding transformer mounted in the center of the upper fixed beam, a control unit, at least one welding circuit containing electrodes, a movable and fixed rod, each of n electrodes connected to the secondary winding of the welding transformer through n thyristor contactors mounted on a fixed rod and connected via single-pin connectors with n channel control unit, made with the possibility of sequential welding of each point, and the electrodes mounted on the upper fixed crosshead provided with elastic elements are communicated through the channels of the crosshead with flexible current leads with thyristor contactors, and the lower crosshead with the second welding circuit rod located on it is movable and connected by ball bearings with connecting rods and eccentrics mounted on the drive shaft, with an electrofusion coupling and a latch that ensures stopping at dead points, and under izhnaya and fixed crosshead guides are connected rectangular, upper parts of which are closed the end cap provided with replaceable liners and pressure gauge, and the crosspiece have a honeycomb structure and made of plywood sets.

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