1 Introduction
In order to meet the needs of large-scale production of the refrigerator compressor, we have developed the compressor sealing shell automatic welding machine, which can realize the full automatic production requirements of the sealing shell welding. The device uses programmable program controller (PLC) control, pneumatic drive, DC speed control, automatic gas shielded arc welding, dual manipulator handling, copying and other technology, and set the air pressure is insufficient, inadequate water pressure, broken wire, gas protection, material full, the profile modeling wheel disengaged, all kinds of alarm system, and good performance, and improve the product quality and production efficiency. Class 600. Successively in Beijing, Zhejiang and other five compressor companies put into use, its performance is reached or exceeded the same kind of imported equipment in Italy, while the cost is only 1/4 of imported equipment.
2 mechanical transmission system
The overall layout of the whole automatic welding machine is shown in Figure 1. Station 1 is the pre assembly station, the operator will be welded to the compressor from the transmission line to the pre installed station (also commonly used a three degree of freedom mechanical hand automatically completed). Press the start button, double manipulator will be pre installed position on the parts to be welded move to processing station (station 2) at the same time, the machining position of welded parts moved to the unloading station (station 3). After the completion of the centering clamping position processing special cylinder, pressure head to shell is tightly pressed in strict and copying slide fast torch began welding. At the same time double manipulator reset, unloading mechanism of action. The operator moves the next job to the pre assembly station, press the start button, and wait for the next work cycle.
2.1 pairs of machine parts
The two parts are mounted on the Longmen stand, as shown in Figure 2. It has a fast retreat, and clamp the three degrees of freedom. Fast retreat speed of up to 800mm/s. Travel terminal buffer deceleration and precise positioning device, to ensure a smooth and fast; to improve stroke terminal limit device is arranged, play a role in the protection of a piston member; loose clamping manipulator is a special structure of the pneumatic actuator, as shown in Figure 3, small volume, high precision, flexible and reliable action unilateral closing stroke is 8mm.
2.2 working table rotating parts
The rotary table is driven by a DC motor (400W, 1500r/min) (i=1: 380), as shown in Figure 4. The upper part of the working platform is centering fixture, its structure and dual manipulator with same structure; the middle part is provided with a cam profile, used to control the relative motion trajectory of the torch and workpiece, to form the elliptic curve; centering fixture as a result of the use of pneumatic transmission, so the bottom is rotating inlet joint, through the spindle center through hole pressure gas sent to clamp cylinder.
The 2.3 part profile table
The structure diagram of the copying table as shown in figure 5. Gun installed in the welding torch position adjusting device, can rotate along the X, Y direction of movement and Z direction, used to welding torch adjusting the optimum tilt angle and arc distance, in order to ensure the quality of the weld. Fast forward back support in the drive cylinder, 50mm can move along the guide for workpiece handling. Compressor on the combined surface of the shell is an ellipse, and when the workpiece rotates around a center, the radius R is a variable value, so it is necessary to torch the corresponding displacement in the X direction, pressure wheel and slide in the copying cam and copying of the cylinder under the control, to achieve the required displacement, an ellipse trajectory.
3 pneumatic transmission system
The welding equipment in addition to the use of the rotary table of the DC motor, the rest of the movement are the use of pneumatic transmission, of which 7 of the cylinder for import, the 3 cylinder is designed and manufactured. Below on the part of the element for a brief description and dual manipulator of the opening and closing, detected by FC1 and FC2 sensor, only when the FC1 and FC2 were on, manipulator only at the opening and closing of a. The pressure head is equipped with three detecting sensor FC7, FC8 and FC9, FC7 and FC9 are the piston moving limit position sensor, and FC8 is the pressure head working position sensor. Only when the FC8 is ON, FC9 can be welded; for ON, showed no workpiece centering fixture, and immediately alarm. Pressure relief valve is arranged inside the loop head, through the valve adjustable pressing head of the pressing force, so that the upper and lower casing tightly closed without centering fixture under too much pressure.
The effect of pressure relay in copying loop is: in the maintenance of equipment, through the manual reversing valve to make the welding torch back; once again into the work, the manual reversing valve connected profiling pressure; when the pressure is 0, machine can not into work, and prevent occurrence of accidents due to misoperation. The pressing force of the pressure head and the copying cam profile by reducing valve in the loop regulation. The total circuit is also installed in the pressure relay, when the pressure is insufficient, the control system alarm, stop welding. The reversing valve used in the system in addition to copying loop using a manual, the rest of the circuit are used for electromagnetic valve.
4 electronic control system
Control system uses SIEMENS's PLC control, the output through the intermediate relay action. PLC consists of 8 input modules and 5 output modules. The input module is mainly composed of 110V power output, manual / automatic selection, all kinds of alarm input, the hands start button, welding machine is switched on, fault reset, pressure testing and implementation of the pieces position signal feedback. The output module includes a connecting welding machine, counting of the workpiece, the positive and negative transfer delay and the driving of the solenoid valve of the actuator. The control system structure diagram is shown in figure 6.
As mentioned above, the upper and lower shells of the upper and lower shells of the joint trajectory is an ellipse, in order to ensure the quality of the welding process, so that the thickness of the weld is uniform and beautiful, it is necessary to ensure that the solder joints in the center of the movement with respect to the ellipse is constant. And when the solder joints are in the short or long axis, the linear velocity is different.