Description
AUTOMATIC M0T0RISED ARM FOR ASP IRATING WELD ING FUMES
Technical Field
The present invention relates to an automatic motorised arm for aspirating fumes released by electric welding operations.
5 Background Art
At present, various models of aspirating arms, both set on dollies and fixed, are available on the market. They essentially comprise two movable pipes connected by means of flexible hose portions consecutively to each other and, at their other ends, to a fixed aspirator set and to an aspirating movable small hood. The two pipes, and l o hence the aspirating small hood, are movable according to a rotation in the extremity about the aspirating set, according to a veπical up and down motion and according to a horizontal opening and closing motion, i.e. approaching and moving away from the fixed aspirator set. The latter two motions are also called declination motions.
All known models of aspirating arms have in common the manual actuation
15 to position the aspirating small hood in a position suitable for aspirating the noxious fumes released by the welding operation. Thus, manual actuation entails the need to interrupt the welding operation to move the aspirating arm, in other words every time the operator moves the welding operation away from a certain point, the aspirating hood must be moved to follow it, but to do so the operator has to interrupt the 0 welding operation. In addition, the time wastage and the cost increase of each welding operation should be considered as well. Moreover, in the long run, the current aspirating arm is scarcely employed at all, with harmful consequences to the work environment, the operators' health, and public health in general.
Disclosure of Invention
The present invention therefore aims to overcome this drawback.
The invention, as it is characterised by the claims that follow, solves the problem of providing an automatic motorised arm for aspirating fumes released by electrical welding operations, comprising a first pipe and a second pipe connected to each other by means of a flexible hose segment, by a union fitting for connecting the extremity of the first pipe with a fixed aspirator set and by a flexible portion for connecting the second pipe to an aspirating hood; the first and the second pipe, and hence the aspirating hood, being movable according to a horizontal rotation in the two directions at the extremity around the aspirator set, according to a compass-like opening and closing motion, i.e. a lateral translation with respect to the welding arc and according to an up and down or vertical motion with respect to the aspirating set itself, motorised arm which, from a general point of view, is characterised in that it comprises: a first pair of light sensors of the electric welding arc, located on said aspirating hood and connected to a first differential electronic circuit for commanding a first gear motor, situated in the extremity of the arm around the aspirator set, for said horizontal rotation of said arm in the two directions; a second pair of light sensors of the electric welding arc, located on said aspirating hood and connected to a second differential electronic circuit for commanding a second gear motor for said compass-like opening and closing movement, located on said arm; a third light sensor, with variable sensitivity, of the electric welding arc, located on said aspirating hood and connected to a comparator electronic circuit for commanding a third gear motor for said up and down motion, located on said arm; a circuit for supplying power to said sensors further comprising a relay for enabling the welding pushbutton; so that the motorised arm moves autonomously searching for the welding arc, positioning itself near it, following it at an adjustable distance.
The motorised arm according to the present invention causes the hood continually to overlie the welding torch whilst the aspirator set aspirates the fumes, to shut itself off after a brief time interval following the end of the welding operation. Further features and advantages of the present invention shall become more readily apparent from the detailed description that follows of preferred embodiments, illustrated purely by way of non limiting indication in the accompanying drawings.
Description of the Drawings - Figure 1 shows a schematic side view of a first embodiment of motorised arm according to the present invention;
- Figure 2 shows a schematic top plan view of the motorised arm of Figure 1;
- Figure 3 shows a schematic front view of the motorised arm of Figure 1;
- Figure 4 shows a block diagram of the automated mechanism of the motorised arm according to the present invention;
- Figure 5 shows a first differential electronic circuit of the automated mechanism of Figure 4;
- Figure 6 shows a second differential electronic circuit of the automated mechanism of Figure 4; - Figure 7 shows an electronic comparator circuit of the automated mechanism of
Figure 4;
- Figure 8 shows a power supply circuit of the automation of Figure 4;
- Figure 9 shows a schematic side view of a second embodiment of automated arm according to the present invention.
Description of the Illustrative Embodiments
With reference to Figures 1 through 3, wherein a first embodiment of the present invention is shown, the automatic motorised arm, indicated in its entirety with the number 10 comprises an aspirator set 11, a first pipe 12, a second pipe 13
and an aspirating hood 14. The first pipe 12 is connected to the aspirator set 1 1 by means of a union fitting 15, the first pipe 12 is connected to the second pipe 13 by means of a flexible hose segment 16, whilst the second tube 13 is connected by means of a flexible portion 17 to the aspirating hood 14. In this first embodiment the fitting 15 connecting the first pipe 12 with the fixed aspirator set 11 comprises a rigid segment 26 pivotingly mounted on the aspirator set 11 whereto is associated a gear motor 18 for the motion of horizontal rotation in the two directions about the aspirator set 11 to follow the welding arc (not shown herein). Tne union fitting 15 further comprises a flexible segment 27 whereto is associated a gear motor 19 for the actuation of the remaining part of the arm according to an up and down motion that displaces the hood 14 vertically with respect to the welding arc.
On the flexible hose 16 is mounted a gear motor 20 situated between the tube 12 and the tube 13 for the relative rotation according to a compass-like opening and closing motion, always to follow the welding arc.
With reference to Figure 4, the scheme for controlling the gear motors 18, 19 and 20 is shown.
A pair of photoelectric cells or light sensors 1, 2, positioned on the hood 14, is connected to a differential electronic circuit 21, to command the gear motor 18 for the horizontal rotatory motion in the two directions, i.e. right and left, of the motorised arm 10.
A pair of photoelectric cells or light sensors 3, 4, positioned on the hood 14, is connected to a differential electronic circuit 22, to command the gear motor 20 for the compass-like opening and closing motion of the motorised arm 10, for a lateral translation with respect to the aspirator set 11.
A photoelectric cell 5, also positioned on the hood 14, is connected to an electronic comparator circuit 23, to command the gear motor 19 for the vertical or up/down or raising lowering motion of the entire arm, i.e. to vary the distance of the hood from the welding arc.
This distance is maintained constant at a value that can be adjusted through sensitivity adjusting means 28, 29, shown in Figure 7.
The position of the sensors is schematically shown in the figures as inside the hood 14 but it should be understood that it may be different, inside the hood or outside it, but, obviously, connected thereto.
With reference to Figure 5, therein a diagram is shown of the differential electronic circuit 21 for commanding the motor 18. Figure 6 shows a diagram of the differential electronic circuit 22 for commanding the motor 20, whereas Figure 7 shows a diagram of the electronic comparator circuit 23 for commanding the motor 19. In particular, in Figure 7, the means 28 for adjusting sensitivity regulates the distance of the hood from the welding arc, whilst means 29 regulates the intervention window.
Lastly, Figure 8 shows a diagram of the circuit 24 for supplying power to the sensors 1, 2, 3, 4, 5 further comprising a relay for enabling the welding pushbutton indicated in 25.
The circuits shown in Figures 5 through 8 are contained in a case, not shown herein.
With reference to Figure 9, a second embodiment of the present invention shall now be described. Similar or corresponding parts are indicated with similar reference numbers. The automatic motorised arm, indicated in its entirety as 100 comprises an aspirator set 1 10, a first pipe 120, a second pipe 130 and an aspirating hood 140. The first pipe 120 is connected to the aspirator set 110 by means of a union fitting 150, the first pipe 120 is connected to the second pipe 130 by means of a flexible hose 160, whilst the second pipe 130 is connected by means of a flexible portion 170 to the aspirating hood 140.
In this second embodiment the connecting union fitting 150 of the first pipe 120 with the fixed aspirator set 110 comprises a Z-shaped rigid union fitting associated for the rotation to a gear motor 180 at one of its extremities and pivotingly connected at the other of its extremities to the first pipe 120 associated for the
compass-like opening and closing motion to a gear motor 200. A gear motor 190 for the up and down motion is located on the motorised arm in the flexible hose 160 between the first pipe 120 and the second pipe 130. Command over the gear motors is similar to the one shown in Figure 4, as are the related differential and comparator electronic circuit.
Preferably, for the safety of the motions, the gear motors 18; 180, 19; 190, 20; 200 are provided with a clutch.
Naturally, the invention thus conceived can be subject to numerous modifications and variations, without thereby departing from the scope of the inventive concept that characterises it.