JPS6049080B2 - Workhead rotation mechanism of laser welding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating mechanism for a work head of a laser welding machine.

Generally, when performing spot laser welding at multiple points, positioning the spot position of the welded material and the condensing position of the laser head is one of the important factors for stabilizing welding conditions.

However, laser welding equipment has a large structure and contains precision parts such as optical systems and laser oscillation parts.
To avoid vibration during movement, the laser head is usually fixed.
Generally, a work head or the like that holds the material to be welded in an assembled shape is moved to position the material to be welded at a desired welding position. Therefore, the accuracy of welding position, assembly dimensions, and welding strength are influenced by the method of positioning the work head. In addition, laser welding equipment is expensive, ranging from several million yen to tens of millions of yen, but it is necessary to perform the welding cycle as quickly as possible, so work supply, assembly, inspection, etc. are performed in separate positions. In many cases, a multi-head assembly method with independent welding positions is used, and in this case, the method of positioning the work head is important. For example, a cathode component for an electron tube as shown in FIG. 1 is assembled by fitting and assembling a thin-walled tubular sleeve 1 and a cup-shaped cap 2, and focusing a laser beam near the outer surface of the cap to a spot point 3. spot weld. This welding is usually performed at multiple points depending on the necessity for reliability. And as a welding method,
This method involves inserting the sleeve 1 and the cap 2 into the core metal, pressing the zenith surface of the cap 2 with a presser rod, rotating the core metal and the presser rod synchronously, and performing laser welding.
A conventional work head rotation mechanism of such a laser welding machine has a structure as shown in FIG.

That is, a plurality of work heads 6 provided on an index table 5 of a turntable assembly machine 4 are rotatably mounted by bearings 8 press-fitted into a jig plate 7. The sleeve 1 and cap 2, which are the materials to be welded, are assembled in advance on the core metal part 6a of the work head 6, as shown in FIG. The cap 2 is held and positioned by the lower end 11a of the intervening spindle 11. At this time, the spindle 11 presses the cap 2 with a constant force due to the pressing force of the cylinder 9. On the other hand, the rotation transmission mechanism of the work head 6 is a rotation shaft 13 of the rotation motor 12.
An upper shaft 16 and a lower shaft 17 are rotated in the same phase by a pair of pulleys 14 and a timing belt 15, and an upper driving wheel 18 and a lower driving wheel 19 attached thereto are connected to a driven wheel 20 and a work head 6, respectively. Friction is transmitted to the transmission surface 6b, and the driven wheel 20 and spindle 11 can be moved up and down by splines, etc., and rotate in the same phase as the work head 6. Further, a laser oscillation signal during welding is outputted by a detection plate 21 and a detection head 22 at a desired rotation angle. The cap holding mechanism lowers the spindle 11 by lowering the cylinder 9, and uses a spring 23 to raise the cap. In addition, in the figure, 24 is a casing,
25 is a fixed frame. As shown in FIG. 4, the lower motor vehicle 19 is attached to a swing arm 27 with a fulcrum shaft 26 as a fulcrum, and when the work head 6 is not in the working position such as when it is moving, it hits the stopper 28 and is in an idling state, but the work Just before head 6 completes its movement, this work head 6
The rotation of the lower drive wheel 19 is transmitted to the plurality of work heads 6 by the pressing force of the spring 29.

Figure 5 shows the pressure mechanism of the upper friction drive.
In order to reliably transmit the rotation of the driving wheel 18 to the driven wheel 20, a movable block 30, a fixed block 31, and a pressure spring 32 are used.
and an adjustment screw 33.

The operation of the conventional mechanism explained above is as follows: First, the workpieces 1 and 2 (see Fig. 1) are assembled on the core metal 6a of the workhead 6, and even when the workpiece head 6 is not transported to the welding position, the rotation motor 12 is activated. The spindle 11 and the lower motive wheel 19, which are constantly rotating and to which power is transmitted, are also continuously rotating.

Next, when the work head 6 comes just before the welding position,
It contacts the lower driving wheel 19 and begins to rotate, and by the time the index table 5 stops, the rotation speed reaches the synchronous speed. As the cylinder 9 descends, the spindle 11 descends while rotating, and when the upper surface of the cap 2 is pressed, the detection plate 21 The laser welding device 34 performs multi-point welding on the outer peripheral surface of the work in conjunction with the operation signal. After welding is completed, the cylinder 11 is raised,
When the index table 5 rotates, the work head 6 separates from the lower motive wheel 19, stops rotating, and performs the next process. As described above, since the conventional work head rotation mechanism performs spot welding by irradiating laser beams while the workpieces 1 and 2 are rotating, the spot surface of the workpieces is irradiated with respect to the laser focus position of the laser welding device 34. It is inevitable that it will form into an elliptical shape over time.

Further, when the work head 6 and the workpiece positioning spindle 11 vibrate during rotation, the energy density of the weld zone fluctuates, thereby making the solubility strength and nugget formation of the weld zone unstable. In addition, as a problem with the conventional mechanism using two sets of friction drives, the driving vehicle 18 and the driven vehicle 2
Since the transmission of zero is by frictional force, it is difficult to transmit synchronous rotation due to the difference in the outer diameter of the contact surfaces, and it is impossible in principle to drive the friction drive mechanism by directly linking it to the work cycle of the assembly machine. Therefore, as in the embodiment, the automatic motor 1
2, it is necessary to use a separate drive method, which is asynchronous to the operation timing of the assembly machine. Since the rotation of the work head 6 is asynchronous, a margin is required in the range in which the laser can be irradiated with respect to the number of welding points on the works 1 and 2. For example, when welding three points on the outer circumference of a workpiece at intervals of 1200, it is necessary to secure a laser irradiation range for four points and controllably extract three points and irradiate them with the laser. As mentioned above, since the synchronization method requires comparative laser irradiation tolerance, it is obvious that the work cycle will be reduced if the repetition time of laser irradiation is constant.

This poses a major obstacle to high-speed operation of the assembly machine. SUMMARY OF THE INVENTION An object of the present invention is to provide a work head rotation mechanism for a laser welding machine that employs a synchronous method by improving the drawbacks of the conventional asynchronous method and can provide stable welding conditions.

In order to achieve the above object, the present invention takes rotational drive from the output shaft of the assembly machine main body, employs two sets of friction drives, and uses a gear transmission mechanism in combination with the upper friction drive mechanism to synchronize with the assembly machine. It is characterized by the following.

The present invention will be explained below based on illustrated embodiments.

FIG. 6 is a front view showing an embodiment of the work head rotation mechanism of the laser welding machine according to the present invention, and FIG. 7 is a perspective view showing the transmission mechanism of the upper friction drive. In addition, the second
Components that are the same as those of the conventional mechanism shown in the drawings are given the same reference numerals and explanations will be omitted. A pulley 42 is attached to an output shaft 41 of a turntable assembly machine 40, and the rotation of the pulley 42 is transmitted by a timing belt 43 to a pulley 46 fastened to an intermediate shaft 45 rotatably supported by a casing 44. . Further, a detection plate 47 is attached to the output shaft 41, and this detection plate 47
A detector 48 is provided for converting the phase angle of the signal into a control signal. The rotational force of the intermediate shaft 45 is transmitted in the same phase to the spindle 11 and the work head 6 by two sets of upper and lower friction drives using the timing belt 15, as in the conventional case, but the difference from the conventional method lies in the upper friction drive. That is, as shown in FIG. 7, a pair of driving gears 50, a driving gear 51, a driven gear 52, and a driven gear 53 are attached to the rotating shaft 16 and the spindle 11, and the output shaft 4 of the assembly machine is attached to the rotating shaft 16 and the spindle 11.
1 and the rotational positional relationship of the spindle shaft 11a were set to be in the same phase. Next, to explain the operation of this mechanism, when the speed increasing ratio of the pulley 42 and the drive gear 50 is 1:3 and the other transmission ratios are 1:1, when the output shaft 41 rotates one cycle, the spindle 11 and the workpiece The head 6 rotates three times.

Now, if it takes 213 cycles to move the work head 6 and position the works 1 and 2, and 113 cycles to weld, the welding timing for one rotation of the spindle 11 and work head 6 is secured, and the trigger signal of the detection plate 21 is specified. This allows for arbitrary multi-point welding around the entire circumference of the workpiece. Furthermore, the control method of this mechanism, which can be synchronized with the assembly machine, has been improved, and the details thereof will be explained with reference to the control block diagram shown in FIG.

In the case of the control of the conventional mechanism shown in Fig. 2, since it is an asynchronous type,
As shown in FIG. 8a, the pulse input signal 60 of the detection plate 22
and the timing input signal 61 of the rotating motor 12 are selected by the AND circuit 62, and the counter circuit 63 outputs the required number of laser irradiation signals 64. In contrast, the mechanism of the present invention shown in FIG. The pulse input signal 60 of the detection plate 22 and the timing input signal 65 of the detection plate 48 are selected by the AND circuit 62, and the number of signals selected by the AND circuit 62 becomes the laser irradiation signal 64, so the counter circuit 6
3 is no longer necessary, making it possible to significantly reduce the circuit configuration and improving the reliability of the control circuit. As mentioned above, the head rotation mechanism of the present invention is a movable table type multi-head assembly machine, and has a number of characteristics when performing multi-point laser welding. We provide head rotation mechanisms for various irregularly shaped parts.

It is known that when multi-point laser welding is performed on the outer periphery of a mating part like the workpiece in this example, the minute behavior of the work mechanism such as the workhead affects the welding process such as laser irradiation, melting, and solidification. The present invention greatly improves the reliability of workpiece assembly and is effective in increasing the speed of assembly machines.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view showing an example of a workpiece, Fig. 2 is a front view of a conventional head rotation mechanism, Fig. 3 is a front view for supplementary explanation of Fig. 2 showing an assembled state of the workpiece, and Fig. 2 is a front view of a conventional head rotation mechanism. Fig. 4 is a plan view for supplementary explanation of Fig. 2 showing the lower friction drive, Fig. 5 is a plan view for supplementary explanation of Fig. 2 showing the upper friction drive, and Fig. 6 is an implementation of the head rotation mechanism of the present invention. FIG. 7 is a partially cutaway perspective view for supplementary explanation of FIG. 6 showing the upper friction drive, FIG. 8 shows the control system, a is a professional hook diagram of the conventional example, and b is a diagram of the present invention. It is a block diagram in a mechanism. 1... Sleeve, 2... Cap, 5...
... Index table, 6 ... Work head, 6b ... Transmission surface, 11 ... Spindle, 18 ... Upper prime mover, 19 ...・・・
・・Lower drive vehicle, 20・・Driven vehicle, 21・・・・
...Detection plate, 22...Detection head, 34...
...Louser welding equipment.

Claims (1)

[Claims] 1 In an automatic laser welding machine, two sets of friction drives or other rotation transmission mechanisms using the assembly machine main body as a drive source are used to rotate a spindle equipped with a mechanism for applying work to a workpiece, and a workpiece installed on an index table. The rotation of the holding work head is synchronized and transmitted to the upper friction drive section using a synchronous rotation mechanism, and a detection section is provided on these rotating parts to output an arbitrary rotation position signal, and this signal is used to detect the rotation during rotation. A work head rotation mechanism for a laser welding machine, characterized in that the work head rotation mechanism of a laser welding machine performs welding by irradiating an arbitrary number of laser points on a material to be welded.