Prior Art The electrical spot welding which is a process of joining metal sheets by melting them at one point using high electrical current, is intensely used in metal industry. The welding guns used in this operation are produced by using the cast iron body method.

In the state of art, the welding gun bodies are produced as cast iron of different types and dimensions for quite limited range of use and a predetermined clamp opening, depending on the pressure forces. As the welding gun capacities are such values as length, clamp opening, electrode axes gaps, momentum, and the like, which are defined separately for each type, and since there is not any other chance of adjustment, a different type of welding gun is required for each model.

This requirement for a separate model-gauge for each new type of the welding gun that is needed, with respect to the production technique, has a negative impact on the speed and cost of production.

Certain deformation problems seen on the welding gun structures that are made of cast copper, lead to the direct discarding of said welding gun. This results in a requirement for storing different spare parts for each type of copper welding guns.

The Object of the Present Invention The object of the present invention is to develop a modular spot welding gun, that provides a multi-purpose production flexibility which is not dependent on the geometry and sheet thickness of the spot welding zone.

The modular welding gun realized to attain the above mentioned objective of the present invention, has been illustrated in the attached drawings, wherein; Figure 1, is the schematic view of the modular welding gun according to the invention; Figure 2, is the schematic view of the prior art welding gun.

The components shown in the drawings have individually been enumerated as follows: 1. Modular welding gun 2. Lower clamp 3. Upper clamp 4. Joint 5. Cylinder 6. Electrode holder 7. Welding electrodes 8. Spacer piece The modular welding gun (1) of the present invention, comprises the lower- and upper-clamp (2,3), joint (4) and cylinder (5) that are standard and do not change according to the type and size, and also comprises an electrode holder (6), welding electrodes (7) and the spacer piece (8), which change according to different areas of usage.

The lower and upper clamps (2,3), being among the standard parts of the modular welding gun (1) of the invention are made of stainless steel, aluminum or a bronze alloy material.

The electrode holders (6) are attached to upper and lower clamps (2,3). The cylinder (5) fixed between the upper and lower clamps (2,3), provides the force required to enable the opening closing movement of the modular welding gun (1).

The electrode holder (6), being one of the parts that provide the modularity of the welding gun (1) is made of a highly conductive material, preferably of copper. The electrode holder (6) made of a material cast as a solid or hollow tube provides the conduction of the electrical current and of the cooling fluid.

It is made of a material having a hardness ratio (HBR) greater than 72, with respect to the material strength feature.

The welding electrodes (7) used in the modular welding gun (1) according to the present invention are removably fastened to the electrode holders (6).

Welding electrodes (7) of different length and diameters can be used with the same electrode holder (6), depending on the usage area of the welding gun (1). The welding electrodes (7) that provide a flexibility of use to the welding gun (1) are made of conductive material, preferably of copper.

A spacer piece (8) is used to connect the lower and upper clamps (2,3) to which, the electrode holder (6) are attached.

One end of said spacer (8) is fixed to the upper clamp (3) and the other end is attached to the lower clamp (2) by means of a joint (4). The spacer piece (8) enables the lower and upper clamps (2,3) to move along a vertical axis.

In case the axis gaps of the electrode holders (6) are decreased, the modular welding gun (1) and the cylinder joint assemblies may be converted to a monobloc structure.

The modular welding gun (1) capacities can be adjusted according to the area of usage, by virtue of the spacer piece (8), electrode holder (6) and welding electrode (7).

By changing one or more of the spacer piece (8), electrode holder (6) and welding electrode (7) parts, according to the geometry of the area to be welded and to the sheet thickness, the capacity adjustments such as the length, clamp opening, electrode axis gaps and momentum can suitably be adapted, without changing such parts as the lower and upper clamp (2,3), cylinder (5) and joint (4).

The welding gun (1) according to the present invention, provides considerably advantages with respect to production investment costs and time, due to its modular production structure. The possibility of replacing the worn parts and material, increases the service life of the modular welding gun (1).

Furthermore, reducing the types and standards to be used, facilitates the production estimates, lowers the stock (storage costs) and eliminates the difficulty of management.