GB2077167A - Welding mask - Google Patents

Abstract

The present invention relates to a welding mask having a dark coloured glass or plastics material vizor for covering a viewing aperture of the mask and a solenoid 4 which, when activated, serves to clear the line of vision through the aperture; the solenoid being arranged such that, on cessation or in the absence of current therein, the said aperture is covered by the dark coloured vizor. The welding mask provides increased protection to the eyes of the wearer, in particular from intense arc light, the arrangement being such that the line of vision through the viewing aperture is only cleared when no current is flowing to the arc electrode, and the dark coloured vizor covers the viewing aperture before the striking of the arc. The vizor itself may be intrinsically dark-coloured and removable from the line of vision or may be created in the line of vision, e.g., and as shown, by the relative rotation of two polarized filter plates 24, 26. <IMAGE>

Description

SPECIFICATION Welding mask This invention relates to a welding mask.

It is presently the case that protection against injury to the eyes during welding is provided by means of a hand-held or headmounted mask constructed of opaque material with an aperture covered by dark coloured (normally green) glass or plastic through which the welder may view the object being welded.

Under normal circumstances, the weld is commenced by the operator approximately positioning the arc electrode on the object to be welded then moving the mask into place between the eyes and the weld area. With the mask in position the electrode and the object to be welded are not visible to the operator until the arc is "struck" whereafter the operator may follow the weld visually through the darkened glass. However, if the mask is not correctly positioned, there is a danger that the arc will be struck too soon which may result in intense arc-light or a spark entering the eye giving rise to the painful condition known as "arc-eye" or even to serious physical damage.

According to one aspect of the present invention there is provided a welding mask having a dark coloured glass or plastics material vizor for covering a viewing aperture of the mask and an electric motor which, when activated, serves to clear the line of vision through the aperture; the motor being arranged such that, on cessation or in the absence of current therein, the said aperture is covered by the dark coloured vizor. The provision of current to the motor may conveniently be controlled by a switch or trigger remote from the mask and preferably located on the electrode holder which trigger may also control the current to the welding electrode.

The aperture will then be covered by the dark coloured visor immediately before the arc is struck.

The term "electric motor" is intended to include any electrical device for producing motion such as linear or rotary solenoids, motors or other transducers.

Thus the present invention provides a welding mask through which the operator may see the weld area with safety before during or after the actual operation of welding and not be required manually to remove and replace the mask in order to be able to see the weld area.

The mask of the present invention, being such that the darkened vizor covers the viewing aperture unless current is flowing through the motor, is advantageous from the point of view of operator safety. This advantage arises from the fact that, in the event of an electrical failure in the motor circuit, the operator's eyes will remain protected and so injury thereto will be avoided.

The dark coloured vizor of the mask of the invention may be intrinsically dark-coloured and removable from the line of vision of the operator through the viewing aperture or alter- natively it may be created in the line of vision, e.g. by the relative rotation of two plates of polarized glass or plastics material.

Where the dark coloured vizor is to be created by relative rotation of plates of polarized material, a relative rotation of about 90 will generally be required to convert from a vizor giving an acceptable degree of visibility of the workpiece when the arc is not struck to a a dark coloured vizor giving sufficient protection to the eyes of the operator when the arc is struck. It will generally be convenient for one of the two plates of the vizor, suitably that plate remote from the eyes of the operator, to be held fixed relative to the mask, the other plate being provided with means whereby its rotation may be effected by the action of the motor.The movable vizor plate will preferably be provided with resilient means against which the notor may act and which serve to maintain the vizor in its darkened configuration in the absence of current through the motor.

When the vizor of the mask is inherently dark-coloured, it will preferably be provided with resilient means by which the vizor is urged into position covering the viewing aperture. In this case, the darkened vizor of the mask of the present invention is conveniently in the form of a plate able to slide in freerunning guides in a direction substantially perpeodicular to the operator's line of vision through the aperture in the mask and such as to cover or expose the said aperture. In the absence of current flowing through the motor the vizor preferably is returned to covering the aperture by the aid of a spring which is relaxed by the closing of the vizor. Conveniently the spring is compressed when the vizor is opened.

Thus according to a further aspect of the present invention there is provided a welding mask having a vizor for covering a viewing aperture of the mask wherein the vizor comprises two plates of polarized glass or plastics material arranged to be capable of relative rotation under the action of an electric motor whereby the line of vision is cleared as a result of the increase in light transmittance through the visor; the motor preferably being coupled for control to the welding circuit.

In the mask of the invention wherein the vizor comprises two polarized plates, a further clear glass or plastics material protective plate is preferably positioned adjacent the vizor plates across the line of vision and remote from the eyes of the operator. This protective plate will serve to protect the vizor and the eyes of the operator from sparks and solid debris. Where a protective plate is provided, the thickness of the polarized plates of the vizor may be reduced. Where one polarized plate of the vizor is fixed relative to the mask the second, rotatable, polarized plate will conveniently be in the form of a circular disc mounted on a centrally positioned pivot about which it may rotate.

According to a yet further aspect of the invention there is provided a welding mask having a dark coloured glass or plastics material vizor for covering a viewing aperture of the mask wherein the vizor may be removed from the line of vision through the aperture by the action of an electric motor; the vizor being in the form of a plate able to slide in freerunning guides in a direction substantially perpendicular to the line of vision and such as to cover or expose the said aperture; and the motor preferably being coupled for control to the welding circuit.

The guides are advantageously provided with a plurality of freely rotating rollers, for example of metal or of a low friction material such as polytetrafluoroethylene.

As a further safety precaution the vision aperture in the mask of the present invention may conveniently be provided with a fixed clear glass or plastics material covering panel.

With the movable vizor covering the vision aperture, this fixed panel may be positioned interiorly of the vizor or exteriorly of the vizor.

Alternatively, two such fixed panels may be provided; one on either side of the vizor. The advantage of such a fixed covering panel lies in the protection afforded to the eyes when the vizor is retracted during such operations as, for example, the chipping of hot scale from a completed or partially completed weld.

The guides, moving vizor and fixed panel, while most conveniently being planar in form may otherwise be shaped to the contours of the mask. The vizor is itself most conveniently lifted generally vertically, i.e. perpendicularly to the line of vision of the operator.

The motor drive for the vizor may itself be mounted on or incorporated into the mask above, below or to one side of the vision aperture thereof and may consist of one or more motor drive units.

According to a yet further aspect of the present invention there is provided welding apparatus comprising a welding mask according to the invention, a welding electrode, an electrode holder, and a welding circuit, wherein the controls for the motor of the mask and for the electode are located on the electrode holder.

The current to the motor as indicated above is conveniently controlled by the same switch or trigger that controls the current to the arc electrode. This switch, for example mounted on a hand held electrode holder, would therefore advantageously have three operating positions.

In the first such position -"off"- the motor is energised (the welding unit being attached to a current supply) and the line of vision of the operator is cleared, e.g. by the retraction of the darkened vizor or by the rotation of the rotatable polarizing filter relative to the static filter of the vizor.

In the second position -"stand-by"- the motor is de-enerigsed and the vision aperture reverts to being covered by a dark-coloured vizor. In this and the first position no current is provided to the arc electrode.

In the third position -"on"- the motor remains de-energised while the arc electrode is energised and thereby the welding arc is "struck".

In an alternative embodiment, the second position of the switch (stand-by) may be omitted if the circuit is provided with a delaying means such that, on switching from "off" to "on" there is a time delay before the current to the arc electrode commences, thereby enabling the vizor to close or rotate to the darkened configuration before the arc is struck.

One example of such a delaying mechanism is the provision to the vizor of a circuit-breaker whereby a circuit is broken (or connected) only when the vizor is closed or in the darkened configuration and only thereafter can the arc electrode be energised.

To achieve the above system the mask must be electrically connected to the switch and the electrode holder should be formed to incorporate the switching device. The power supply to the motor may be provided by a suitable transformer using a small portion of the voltage supplied to the arc electrode. The electrical connection referred to will conveniently be in the form of a removable electric lead provided with a socket capable of engaging with a , plug attached to the mask and electrically connected to the motor drive unit.

The mask of the present invention effectively ensures that the eyes of the operator are always protected. As the time lag (resulting from a multi-position switch or a time delay switch as described above) between the vizor coming into place covering the vision aperture or rotating to the darkened configuration and the striking of the arc is minimal, the operator has a clearer knowledge of the relative positions of the workpiece and the electrode and so is not required to glance at a potentially harmful source of arc light.

Several preferred exemplary embodiments of the present invention are illustrated in the accompanying drawings in which: Figure 1 is a side elevation of one embodi- ment of a mask according to the invention; Figure 2 is a front elevation of the mask of Fig. 1; Figure 3 is a partial vertical section through the mask of Fig. 1; Figure 4 is a schematic illustration of the operating principle of the inherently dark-coloured vizor of Fig. 1; Figure 5 is an exploded perspective view of a further embodiment of the mask of the invention; Figure 6 is a partial rear elevation of the mask of Fig. 5; Figure 7 is a partial section through the mask of Fig. 6 viewed along line ZZ; Figure 8 is a side elevation of the electrode gun; Figure 9 is a representation of the three operating positions of the switch on the electrode gun; and Figure 10 is an electrical circuit diagram of the mask.

Referring to the drawings in detail, in the first embodiment a welding mask 1 of opaque material is provided with an aperture 2 therein through which the operator may view the object to be welded. The mask illustrated in Figs. 1 and 2 is a head-mounted version and is secured to the head of the operator by means of straps 3.

Mounted on the mask 1 is a solenoid drive unit 4 which, by means of a plunger 5 attached to a darkened vizor 6 by a holder 7, may serve to retract the vizor 6 from in front of the vision aperture 2. The vizor 6 shown in these drawings is in the form of a sliding plate.

In Figs. 4a and 4b the operating principle of the mask is illustrated showing respectively the vizor 6 retracted from and covering the vision aperture 2. The line of sight from the eye 8 of the operator through the vision aperture 2 is shown by a dotted line. In Figs.

4a and 4b is also shown the fixed clear panel 9 which may serve to provide further protection for the eyes of the operator when the vizor 6 is retracted. In these drawings the fixed clear panel 9 is shown positioned interiorly of the vizor 6.

Around the plunger 5 is positioned a compression spring 10 which is compressed by the retraction of vizor 6 and which, on cessation of the electric current from leads 39 to the solenoid drive unit 4, relaxes and thereby serves to return the vizor 6 to the position covering the aperture 2. The spring 10 is shown in the (relatively) extended and compressed configurations with the vizor 6 correspondingly in the closed and retracted positions in Figs. 1 and 2 respectively.

The motion of the vizor 6 is defined by the guides 11 which are provided with freely rotating rollers 12 of metal or a low friction material. To prevent the cracking or splintering of the vizor 6 on the return thereof to the closed position, a soft or semi-rigid buffer 13 is provided.

A A second embodiment of the mask of the invention is shown in Figs. 5, 6 and 7.

Referring to these drawings in detail, a welding mask body 1 of opaque material is provided with an aperture 2 through which the operator may view the object to be welded.

The mask body 1 is provided with two polarized filters of plastics material one 24 of which is mounted on base plate 25 and thereby is held in place over the viewing aperture 2 and is not capable of rotary motion relative thereto. The second polarizing filter 26 is mounted on a pivot 27 and is capable of at least partial rotation thereabout, i.e.

about an axis substantially parallel to the operator's line of vision. Filter 26 is positioned between and substantially parallel to base plate 25 and a cover plate 28 on which is mounted a solenoid drive unit 4 by means of which filter 26 may be rotated.

The arm 29 of the drive unit 4 is attached to a gear wheel 30 mounted rotatably on a spindle 31 and itself connected by link arm 32 to a fulcrum pin 33 on filter 26. The fulcrum pin 33 is also connected by a tension spring 34 to the cover plate 28. Current through the solenoid of drive unit 4 causes the motion of arm 29 which motion is transmitted by the gear wheel 30 and the link arm 32 and causes filter 26 to rotate. This rotation extends spring 34 and, on cessation of the current, spring 34 will contract and thereby rotate filter 26 in the opposite sense. The periphery of filter 26 is provided with abutments 35 and 36, conveniently by the formation of filter 26 in the shape or a circular disc from which a peripheral arcuate portion is removed.Rotation of filter 26 brings abutments 35 and 36 into contact with mounting bolts 37 and 38 thereby defining the extent of rotation posible under the action of spring 34 or drive unit 4 respectively. The angle of rotation between the rotation limits is about 90 and the planes of polarization or filters 24 and 26 are aligned to minimize light transmission through the filters when abutment 35 is in contact with bolt 37 and to maximize transmission when abutment 36 is in contact with bolt 38. On cessation of current through the solenoid drive unit 4 therefore a dark coloured vizor will be generated in the line of vision of the operator.

Current to the solenoid drive unit 4 is provided by electrical leads 39.

The fixed polarized filter 24 is protected from sparks or mechanical damage by a clear protective plate 40 of glass or plastics material mounted externally of the mask body to cover the viewing aperture 2. The protective plate 40 is held in place by a mounting flange 41.

The current to the solenoid drive unit 4 and to the arc electrode 14 is controlled by the switch 15 mounted on the handle 16 of the electrode gun.

The switch 15 may be in positions A, B or C (shown in Fig. 9) corresponding to "off", "stand-by" or "on" as described above. In the "off" position only the solenoid 4 is energised. The gun is connected by lead 17 to a transformer 18 and to the mask.

The arc electrode 14 is itself held by an insulated grip 19 attached to the electrode holder 20 which itself is provided with the handle 16. In Fig. 8 is also shown the elec trode lever 21.

The wiring circuit relating to the switch 15 and the solenoid drive unit 4 is shown in Fig.

10, indicating the three positions A, B and C of switch 15. The control circuit voltage indi cated by 22 while the welding transformer current supply to the arc electrode is indicated by 23. It may therefore be seen that current only flows through solenoid 4 to retract vizor 6 or rotate filter 26 when switch 15 is in position A, and only through the relay 18, to activate the arc electrode, when switch 15 is in position C.

Claims (13)

1. A welding mask having a dark coloured glass or plastics material vizor for covering a viewing aperture of the mask and an electric motor which, when activated, serves to clear the line of vision through the aperture; the motor being arranged such that, on cessation or in the absence of current therein, the said aperture is covered by the dark coloured vizor.

2. A mask as claimed in claim 1 wherein the said vizor is in the form of an inherently dark-coloured plate which may be removed from the line of vision by the action of the motor when activated.

3. A mask as claimed in claim 2 wherein the said vizor is provided with resilient means serving to maintain the vizor within the line of vision or to return the vizor to within the line of vision.

4. A mask as claimed in claim 1 wherein the said vizor is in the form or two plates of polarized glass or plastics material positioned within the line of vision and capable of rela tive rotation under the action of the motor thereby generating a dark colouring by de creasing light transmission.

5. A welding mask as claimed in claim 4 wherein the said plates of polarized glass or plastics material are provided with resilient means serving to maintain the relative rotation of the plates at a configuration wherein light transmittance through the plates is minimized or to rotate the plates to such a configuration.

6. A mask as claimed in any one of claims 1 to 5 further provided with a clear protective plate across the line of vision and frontally of the vizor.

7. A welding mask having a dark coloured glass or plastics material vizor for covering a viewing aperture of the mask wherein the vizor may be removed from the line of vision through the aperture by the action of an electric motor; the vizor being in the form of a plate able to slide in free-running guides in a direction substantially perpendicular to the line of vision and such as to cover or expose the said aperture.

8. A welding mask having a vizor for covering a viewing aperture of the mask wherein the vizor comprises two plates of polarized glass or plastics material arranged to be capable of relative rotation under the action of an electric motor whereby the line of vision is cleared as a result of the increase in light transmittance through the visor.

9. A mask as claimed in any one of claims, 1 to 8 for use with an arc electrode provided with a source of electric current for the motor, and means whereby the said current is terminated on the striking of an arc at the electrode.

10. A welding mask substantially as hereinbefore described with reference to the accompanying drawings.

11. Welding apparatus comprising a welding mask as claimed in any one of claims 1 to 10, a welding electrode, an electrode holder, and a welding circuit, wherein the controls for the motor of the mask and for the electrode are located on the electrode holder.

12. Welding apparatus as claimed in claim 11 wherein the said controls are in the form of a three-position switch mounted on the electrode holder, in the third but not in the first and second of which current is supplied to the welding electrode and in the first but not in the second or third of which current is supplied to the motor to clear the viewing aperture.

13. Welding apparatus as hereinbefore specifically described with reference to the accompanying drawings.