GB2032825A

GB2032825A - Welding apparatus with automatically operated fume extractor

Info

Publication number: GB2032825A
Application number: GB7841488A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-10-21
Filing date: 1978-10-21
Publication date: 1980-05-14

Abstract

A fume extractor is operated automatically on actuation of a gas or, as shown, arc welding apparatus. As shown, a control circuit comprises a pair of contacts (28, 30) actuable by a welding transformer (12), the AC current from the transformer (12) being rectified to provide a low- voltage DC current for energizing an electric motor (54) which drives a suction fan (60) forming part of the fume extractor. The fume-laden air from the welding station is sucked by the fan (60) through coarse and fine filter material, the clean, filtered air being exhausted through a nozzle towards the welding station to assist in retaining some of the welding fumes in the region thereof. Energization of the fan motor is accompanied by energization of a solenoid 40 rendering a facial protector operative. <IMAGE>

Description

SPECIFICATION Welding protection The present invention relates to respiratory tract protectors for use with welding equipment, particularly, arc welding equipment.

The present invention provides welding apparatus comprising actuable welding means and a respiratory tract protector which, on actuation of the welding means, is automatically operated to draw fume-laden air from the welding station through filter means such that deleterious fumes are retained within the filter means, the resultant filtered air being returned to the atmosphere surrounding the welding station during the welding operation.

Preferably, the automatic operation of the protector is controlled electrically from, say, the electrical power source of an arc welding means.

However, for gas welding, suitable means may be provided, such as a solenoid or mechanicallyoperated switch or relay, which causes an electric signal to effect automatic operation of the protector. Preferably, the fume-laden air from the welding station is drawn through the filter means by, say, an electrically-driven suction fan, when the welding operation is commenced and subsequently during the whole welding operation.

In order that the invention may be fully understood, embodiments in accordance therewith will now be described by way of example and with reference to the accompanying drawings in which: Fig. 1 is a schematic diagram of an electrical control circuit for actuating a suction fan for a fume extractor associated with welding equipment: Fig. 2 is a schematic diagram of a modified form of control circuit shown in Fig. 1; and Figs. 3A and 3B are partial elevational and full elevational views, respectively, of a fume extractor for use with the circuits shown in Figs. 1 and 2.

Referring to Fig. 1, an electrical control circuit for arc welding equipment comprises a ganged switch 2 in the line conductor of an AC mains supply having switch contacts 4, 6. The circuit from the contact 6 of the switch 2 passes through the primary winding 14 of a step-down welding transformer 12 and through two further switch contacts 8, 10 and, subsequently, back to the AC supply along the neutral conductor thereof.

A pair of welding connectors 24, 26, of which 26 is the earth connector, extend from the secondary winding 18 of the transformer 1 2 and pair of relay contacts 28, 30 are located on the surface of the core 16 of the transformer, terminals 20, 22 being connected to the winding 1 8 in respective conductors to the connectors 24, 26.

A diode rectifier 32 is connected to the contact 30 to provide a DC output signal to the remainder of the circuit, via a smoothing capacitor 34 connected between output terminals 52 and 38. A conductor from another terminal 36 connects with the coil winding terminal 42 of an electro-magnet 40 and to a terminal 56 of a motor 54. Another, output terminal 58 of the motor 54 and output terminal 44 of the electro-magnet 40 are both connected to the terminal 52, a spring-biased operating arm 46 being located on the electromagnet, the function of which is to operate a facial, and particularly an eye, protector, as described and claimed in my co-pending British Application No , entitled "Weiding Protection".

Operation of the circuit of Fig. 1 is described as follows. When the switch 2 is actuated from the OFF to the ON position, AC current flows through the primary winding 14 of the step-down welding transformer 12, thus causing AC current to flow to the welding connectors 24, 26. Current from the secondary winding 1 8 is also rectified by the diode 32 and smoothed by the capacitor 34 to provide a low voltage DC current to the remainder of the circuit. The pair of contacts 28, 30 are not closed until the magnetic field is generated in the transformer 12, that is, when the welding operation is commenced.Thus, when the contacts 28, 30 are closed, current passes from the terminal 20 via contacts 28,. 30, the rectifier diode 32 and the capacitor 34 to the terminal 42 of the electro-magnet 40 and terminal 56 of the motor 54, and subsequently returns to the neutral terminals 50, 52 via terminals 44 and 58, respectively. Thus, the motor 54 is operated to rotate its associated suction fan 60 which forms part of a fume extractor, as shown in Figs. 3A and 3B. Simultaneously, the iron core 48 is attracted by the coil (not shown) of the electro magnet 40 to operate the arm 46 against its spring bias and, consequently, locate a facial protector, as described in my co-pending British Patent Application, detailed above, from a non-operative to an operative position.

If the welding operation is interrupted or terminated, then the relay contacts 28, 30 open, due to the disappearance of the magnetic field within the transformer 12, to stop the motor 54 and fan 60 of the fume extractor and to cause the consequential relocation of the facial protector from its operative to its non-operative position.

Fig. 2 shows a modified form of control circuit to that shown in Fig. 1 and comprises a relay 72 located between terminal 20 and the welding connector 24, instead of the contacts 28, 30 operable by the magnetic field of the transformer 12, as described with reference to Fig. 1. When the welding operation is commenced, the coil 74 of the relay 72 closes movable contacts 76, whereby current flows from the secondary winding 1 8 of the transformer 12 to the motor 54, whilst being rectified and smoothed by the diode 32 and capacitor 34, respectively, as described with reference to Fig. 1.

Referring now to Figs. 3A and 3B, a respiratory tract protector apparatus comprises a fume extractor consisting of a housing 100 having an input opening 102, a mass of coarse filter material 1 04, such as fibreglass, a mass of fine filter material 106, such as active carbon, and the suction fan 60 driven by the electric motor 54 via electric terminals 56, 58. The input opening 102, the coarse filter material 104, the fine filter material 106 and the suction fan 60 are separated by respective stainless steel meshes 108, 110 and 112.

With the inlet opening 102 directed towards the welding station and when the welding equipment is turned on, the DC motor 54 is automatically operated to rotate the suction fan 60, whereby fume-laden air 11 8 is sucked into the inlet opening 102, as indicated by the arrows. As the fume-laden air is sucked through the filter material 104,106 such that deleterious fumes and other particulate material are retained within the filter material, whilst clean air is ejected from the housing 100 via an exhaust outlet 114 and an exhaust nozzle 11 6 back towards the welding station. This jet of clean exhaust air 1 20 also assists in retaining some of the welding fumes in the region of the welding station, thus preventing such fumes from being inhaled by the welder.

It can be seen that the present invention provides several advantageous attributes of which some are as follows: 1. The motor 54 is operated by a low DC voltage provided by the step down transformer 12 and rectifier diode 32, whereas in known fume extractors the motor is operated by a high AC voltage.

2. The pair of contacts 28, 30, as shown in Fig.

1, can be detached from the surface of the welding transformer at any time.

3. A specific relay 72 is located between the welding transformer 12 and the live welding connector 24, as shown in Fig. 2.

4. The jet of clean exhaust air 1 20 produced by the fume extractor, as shown in Figs. 3A and 3B, assist in localizing the welding fumes around the welding station to prevent them from being inhaled by the welder.

Claims

1. Welding apparatus comprising actuable welding means and a respiratory tract protector which, on actuation of the welding means, is automatically operated to draw fume-laden air from the welding station through filter means such that deleterious fumes are retained within the filter means, the resultant filtered air being returned to the atmosphere surrounding the welding station during the welding operation.

2. Welding apparatus as claimed in claim 1, wherein the respiratory tract protector is operably controlled by the power source of the welding means.

3. Welding apparatus as claimed in claim 2, wherein the welding means comprises arc welding means, the protector being operably controlled by the electrical power source of the arc welding means.

4. Welding apparatus as claimed in claim 2, wherein the welding means comprises gas welding means, the protector being operably controlled by a solenoid or mechanicallysperated switch or relay which causes an electric signal to effect automatic operation of the protector.

5. Welding apparatus as claimed in any preceding claim, wherein the respiratory tract protector comprises an electrically-driven suction fan which, when the welding operation is commenced and subsequently during the whole welding operation, draws fume-laden air from the welding station into the filter means.

6. Welding apparatus as claimed in any preceding claim, wherein the filter means comprises a mass of coarse filter material and another mass of fine filter material.

7. Welding equipment substantially as hereinbefore described with reference to and as shown in the accompanying drawings.