EP1471548A2

EP1471548A2 - Activation button for electric tools.

Info

Publication number: EP1471548A2
Application number: EP20040076215
Authority: EP
Inventors: Domenico D'alterio
Original assignee: Trafimet SpA
Current assignee: Trafimet SpA
Priority date: 2003-04-22
Filing date: 2004-04-22
Publication date: 2004-10-27
Also published as: ITVI20030086A1; EP1471548A3

Abstract

An activation button (20) for electric tools, in particular for welding torches and/or plasma arc torches that can be used for cutting materials, comprising at least one flexible foil (21), suitably shaped, arranged between two portions (13, 15) of the button (20), which are pivoted together at one end (11) to allow the actuation of the electric tool only in the presence of a manual command given by the operator; the structure of the button (20) is thus extremely reliable in terms of electrical continuity, at the same time ensuring extreme ease of construction and assembly, as well as an overall reduction in production costs, with respect to known solutions.

Description

The present invention refers to an activation button for electric tools and, specifically, for welding torches and/or plasma arc torches, which can be used for cutting materials.
More specifically, the invention concerns a switch mechanism, able to be used for the activation and deactivation of an electric tool, which is extremely improved, from the constructive point of view, with respect to conventional techniques.
Let us make it clear right now that, even if in the rest of this document reference shall be made, for the sake of simplicity and clearness of illustration, to torches for welding and/or cutting materials, such as professional tools to which the activation button object of the present invention can, in particular, be intended, such a constructive structure of the described activation button can easily be applied to any electric tool in general, thanks to the particular reliability of operation, simplicity of assembly and cost-effectiveness of embodiment which distinguishes the button in question.
Welding or plasma arc torches generally include a cylindrical body, an electrode mounted inside the cylindrical body, a nozzle having a central outlet opening, various electrical connections, ducts for the passage of a cooling fluid and/or of a control fluid for the electrical arc (in the case of a plasma arc torch), an electrical feeding unit and instruments for controlling the operation of the torch.
In particular, plasma arc torches can normally be activated by means of a switch device, which, once actuated, determines the release of plasma necessary for carrying out the cutting operation on the material being processed.
A switch device of such a type, constructed according to the prior art and able to be applied, as already stated, not only to torches for welding and cutting materials, but also to other electrical tools in general, can be seen in detail in figures 1 and 2 attached to the present description, in which figure 1 is a plan view of the button, whereas figure 2 is a section view carried out along line II-II of figure 1.
As illustrated in the aforementioned figures 1 and 2, the button 10 is made up of a containing casing 15, which has a continuous outer surface that is suitably shaped (for example, at the grip of the torch), and an inner terminal board 13 suitable for receiving the electrical connections.
Generally, the activation button 10 is completed by a spring 12 necessary for the positioning of the button 10, a pin 11 about which the mobile element 15 rotates and a switch device 14 mounted inside the casing 15.
Furthermore, in the inner terminal board 13 of the button 10 a guide 16 is foreseen, on which the positioning spring 12 is mounted, which is thus compressed between an inner surface of the terminal board 13 and the inner surface of the containing casing 15 of the torch.
The switch 14 typically consists of an electrical actuator, which is activated when the actuator element 17, mounted on the inner terminal board 13, approaches; the activation of the actuator 14 determines an electrical connection between a pair of conductors (not illustrated in the figures), which are connected to the power supply source (also not illustrated in the figures), thus allowing the operation of the torch.
From that which has been described it is clear that the conventional structure of buttons used for the actuation of welding and plasma arc torches and, in general, of certain categories of electrical tools highlights some criticalities, the first of these is relative to the assembly of the various pieces thereof.
Indeed, in order to obtain a correct operation of the actuator 17 mounted on the mobile element 13 it is necessary, according to that which is foreseen by the prior art, to insert a positioning spring 12 between the element 13 and the casing 15 of the torch, which ensures the relative alignment between the actuator 17 and the switch device 14.
It is thus necessary to interposition an element, such as the spring 12, which, in fact, constitutes a body extraneous to the direct operation of the torch and the arrangement of which inside the activation button is highly critical, both in terms of the difficulties in assembly and because it is subject to wear following the sparking caused at the time of activation and deactivation of the switch.
As time passes the carbonaceous deposits that form on the switch 14 tend to increase the resistance of the contact thus worsening the functionality of the button.
Furthermore, the conventional structure of the activation button, as illustrated up to now, is complicated to assemble inside the torch and has relatively high production and operating costs, due to the number of pieces used and the precision of positioning required.
The purpose of the present invention, therefore, is that of avoiding the aforementioned drawbacks and, in particular, that of indicating an activation button for electric tools, the operation of which is extremely reliable and that can be assembled extremely simply, without foreseeing special technical provisions.
Another purpose of the present invention is that of realising an activation button for electric tools, which ensures high reliability, at the same time allowing the operating modes and electrical safety in general to be respected.
A further purpose of the invention is that of indicating an activation button for electric tools that is easy and cost-effective to realise, without the use of particularly expensive components and/or complex technologies.
These and other purposes are achieved by an activation button for electric tools, according to claim 1, to which we refer for the sake of brevity.
Further purposes and advantages of the present invention shall become clearer from the following description and from the attached drawings, provided as a non-limiting example, in which:

figure 1 shows a plan view of an activation button for electric tools realised according to the prior art;
figure 2 is a section view of the activation button according to figure 1 along the line II-II of figure 1;
figure 3 is a schematic view of a single element used inside an activation button for electric tools realised according to the present invention;
figure 4 is a section view of the activation button for electric tools realised according to the present invention;
figure 5 is a plan view of the activation button illustrated in figure 3;
figure 6 is a plan view of an embodiment of the activation button, according to the present invention, alternative to the one illustrated in figures 3 and 4.

With particular reference to figures 3 and 4, which refer to the new solution object of the present invention and in which the elements identical to those illustrated in figures 1 and 2 are identified with the same reference numerals, it can clearly be seen that the structure of the activation button 20 is, according to the invention, extremely simplified, whilst still carrying out the same functions as the conventional button 10 and, thus, ensuring substantially better reliability of operation.
In particular, the button 20 according to the present invention no longer foresees the presence of a centring or positioning spring, like in conventional solutions, to the great advantage of the constructive simplicity, of the reliability of operation and of the containment of production and operating costs.
Moreover, the function of the positioning spring of the button 20 is carried out by a flexible conductive foil 21, suitably shaped and fixed, at an end 22 thereof, to inside a slot 23 formed in the mobile element 13.
The geometrical extension of the foil 21, made from electrically conductive material, is such that it ca be compressed between the casing 15 of the torch and the mobile element 13 of the button 20, when it is actuated.
Regarding this, the configuration like a broken line of the foil 21 is particularly advantageous, since the projections 24 and 25, foreseen at the terminal element 26, engage on respective abutment surfaces, inside the casing 15, so that the end 27 of the foil 21, which is suitably connected to a switch device (not shown in the figures), ensures the electrical continuity, during the actuation of the button, making contact with the actuator device 17.
It is thus clear that the use of a single component, such as the foil 21, suitably designed and realised, simultaneously allows the correct mutual positioning of the elements 13 and 15 and the activation of the tool, ensuring the alignment between the conductive end 27 and the actuator device 17.
In such a way, the problems of a lack of centring and, therefore, of a lack of operation of the tool due to the wear and/or the displacement of the positioning spring, which can occur during the moving of the element 13, are eliminated and, in particular, one avoids having to use a centring element, suitably designed and realised, coupled with the switch device itself, as, however, happens in known solutions.
In preferred embodiments of the invention, the foil 21 can have a flat extension, as shown in figure 4, or else can be suitably shaped, as specifically illustrated in figure 5, to better adhere to the actuation contacts 17.
From the description that has been made the characteristics of the activation button for electric tools, object of the present invention, are clear, just as the advantages are also clear.
It should, in particular, be considered that the mutual movement between the contacts 17 and the spring 27 allows the electrical contact zone to always be kept clean.
The rubbing between the parts in contact removes the carbonaceous deposits and extends the lifetime of the button.
In particular, the aforementioned advantages are represented by:

simplicity of realisation, effective operation and reduction of total production and operating costs, with respect to conventional devices;
reduction of the number of elements necessary for the realisation of the button, with respect to the prior art;
automatic removal of the carbonaceous deposits that form on the contact surfaces, due to the rubbing movement between the part 17 and the spring 27.

It is clear that numerous other variants can be brought to the activation button for electric tools, object of the present invention, without for this reason departing from the novelty principles inherent to the inventive idea, just as it is clear that, in the practical embodiment of the invention, the materials, the shapes and the sizes of the illustrated details can be whatever according to the requirements and they can be replaced with others that are technically equivalent.

Claims

Activation button (20) for electric tools, of the type comprising at least one outer casing (15), able to be actuated manually by an operator and pivoted (11) at a fixed inner element (13) of the tool, and at least one actuator means (17) characterised in that between said outer casing (15) and the fixed inner element (13) of the tool, at least one flexible foil (21) is arranged, suitably shaped, the compression and/or deformation of which determines the activation or the deactivation of the electric tool.
Activation button (20) for electric tools according to claim 1, characterised in that said flexible foil (21) is fixed, at a first end (22) thereof, inside a slot (23) formed in the fixed element (13) of the button (20).
Activation button (20) for electric tools according to claim 1, characterised in that said foil (21) is configured like a broken line and has at least one pair of projections (24, 25), which engage on respective abutment surfaces inside the casing (15).
Activation button (20) for electric tools according to claim 1, characterised in that a second end (27) of the foil (21) is suitably treated and shaped, so as to ensure electrical continuity during the actuation of the button (20).
Activation button (20) for electric tools according to claim 4, characterised in that said second end (27) of the foil (21) is positioned in contact with said actuator device (17) during the activation of the tool.
Activation button (20) for electric tools according to claim 1, characterised in that said flexible foil (21), suitably shaped and positioned, simultaneously allows the correct mutual positioning between said mobile element (13) and the outer casing (15) of the tool and the activation of said tool, ensuring the alignment between said conductive second end (27) and said actuator device (17).
Activation button (20) for electric tools according to claim 1, characterised in that it can be used, in particular, for welding torches and/or plasma arc torches for cutting materials.
Activation button (20) for electric tools according to claim 1, characterised in that said flexible foil (21) is at least partially made from electrically conductive material.