X-1-Type Laboratory Setup for Butt Friction Welding
Abstract Generated abstract
This paper describes the design and operation of the X-1 laboratory setup developed for studying butt friction welding. The installation uses three-jaw chucks, pneumatic axial loading, timed process control, countercurrent motor braking, and adjustable pressure regimes, including constant, smoothly increasing, and stepwise loading during heating and upsetting. A distinctive feature is the use of a tube as the main load-bearing frame enclosing the headstock and tailstock, which helps maintain coaxiality, reduces bending from axial force, lowers metal consumption, and simplifies manufacture. The setup served both experimental purposes and as preparation for a larger production installation for welding bearing-steel waste products.
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PROCEEDINGS
OF THE TOMSK ORDER OF THE RED BANNER OF LABOR POLYTECHNIC
INSTITUTE named after S. M. KIROV
Vol. 139 1965
X-1-Type Laboratory Setup for Friction Butt Welding
V. V. ILYIN, G. N. KOK, A. F. KNYAZKOV
At the Department of Equipment and Technology of Welding Production, a laboratory setup of the X-1 type has been created for studying the friction-welding process.
Basic Data of the Setup
- Largest diameter of the workpiece to be welded:
of ShKh—15 steel — 14 mm,
of low-carbon steels — 25 mm. - Greatest total length of the workpieces to be welded — 220 mm.
- Maximum axial force at an air pressure of 6 kg/cm² — 2000 kg.
- Number of spindle revolutions per minute — 2850.
- Electric-motor power — 7.5 kW.
Since the setup is intended for laboratory investigations, productivity is not the decisive factor in selecting the type of clamps. In order to make the setup more universal, the workpieces to be welded are clamped in three-jaw lathe chucks, with the chucks holding the part only against rotation. To prevent axial slipping when axial pressure is applied, the parts bear against supports: one against the shaft, the other against the rod of pneumatic cylinder 2, on which the tailstock is mounted.
The main units of the setup (Fig. 1) are: the headstock and tailstock, the cylinder, the electric motor, and the bed mounted on a stand made of angle irons.
In its design the setup differs from existing domestic friction-welding installations in that its principal elements (the tailstock and headstock) are enclosed in tube 8, which serves to take up the axial forces, is the guide for the upsetting mechanism, and is the main load-bearing element of the structure. With such a machine design, precise coaxiality of the parts to be welded is obtained without additional fitting and alignment of the machine units. The symmetrical arrangement of the system that takes up the axial force, relative to this force, ensures the absence of bending moments due to the axial force.
To give the tube greater rigidity against radial vibrations due to unevenness of the ends of the workpieces, the main tube 8 is enclosed by a half-tube and welded to three channels, as shown in Fig. 2. All the forces acting during the welding process are closed within the above-described frame in the form of a tube with flanges; therefore, a sufficiently light support is adequate to hold it.
Fig. 1.
On the left, the front headstock is inserted into the tube; it consists of housing 6 and shaft 2 with a flange to which chuck 7 is fastened. The other end of the shaft is connected directly to the electric motor. The shaft rotates in double radial bearings 3 and 5. To absorb the axial force,
Fig. 2.
thrust ball bearing 4 is used. On the right, the rear headstock is inserted into the main tube; it consists of guide cylinder 10, secured at the end of rod 11 of the pneumatic cylinder. Lathe chuck 9 is fastened to the cylinder. The pneumatic cylinder and the front headstock are connected to the main tube by means of flanges. A window is cut in the tube,
through which the blanks are inserted and the welded parts removed, and through which the friction-welding process is also observed visually.
The specimens for welding are inserted through the window into the chuck and, through special holes in the main tube, are tightened with a wrench. The electric motor is then started, and at the same time the electropneumatic valve is switched on, supplying air to the cylinder. The blanks begin to move together.
Control of the welding process is carried out according to time. The time relay is started manually by a toggle switch at the moment the blanks come into contact and, after counting off the holding time required for heating the end faces, gives the command to brake the motor. The second time relay is started automatically at the moment the motor is braked and counts off the holding time required for upsetting without rotation, after which it gives the command to release the air from the cylinder.
On the X-1 installation, welding can be performed at constant, smoothly increasing, and stepwise pressure, when heating is carried out at reduced pressure and, for upsetting at the moment of braking—or somewhat ahead of it—increased pressure is supplied by admitting air from a cylinder at a pressure of 10–15 atm into the upsetting cylinder. In this case, the duration of action of each pressure stage can be regulated over wide limits.
Braking of the electric motor is carried out by countercurrent, with speed control by means of a tachogenerator with permanent magnets, from which the relay is powered; this relay gives the command to switch off the motor when a speed equal to zero is reached.
The use of a tube as the main load-bearing structural element of the machine made it possible to substantially reduce the metal consumption of the machine and, more importantly, to simplify the manufacturing technology. The entire machine was built by the laboratory assistants and students of the department.
The installation was developed in preparation for the construction of a production installation intended for friction welding of waste from bearing manufacture—products made of ShKh-15 steel with a diameter of up to 60 mm.