DESCRIPTION

LINEAR ACTUATOR WITH JUNCTION ELEMENTS IN PRESSURE DIE-CASTING MONOLITHIC CONSTITUTION

TECHNICAL FIELD

The above mentioned refers to a linear actuator , realised using junction elements which were buϋt with a die-cast technique.

BACKGROUND ART

As known, whenever movement systems, which are the base of industrial automation, are realised, linear actuators are frequently used . These are based on hydraulic or electro-mechanical technologies.

Such movement systems can also be used to create major shifts (four metres long distances ), which may not be back straight, meaning they could involve curved trajectory. The manufactures of these systems must guarantee specific mechanical characteristics which were previously requested by the buyer.

Therefore, there is a necessity to assemble, pack and send whole

"systems of actuators" as well as dealing with logistical and economic issues.

At present, the assembly of al l parts takes place with particular j unction elements that requ ire much care and attention duri ng the bui lding process, which is why it is believed to be a job for the actuators makers themselves, not recommended to be done by the factories using them.

The mentioned factories prefer to receive the actuators when they are already assembled by the makers, so that their functionality can be guaranteed. This is because factories are aware of the type of difficulties that may arise during the assembly of the actuators. Many are the types of actuators currently known. They are basical ly made of a gu ide, on which a motor truck sl ides and movement means of the mentioned motor truck. The linear movement is produced by a trapezium or spherical screw, or through a toothed belt. The actuators are completed by many other in-between elements, needed for the assembly of al l parts, as wel l as the conjunction between the actuator and the plant to move.

At present, these elements are realised in either al umin i um or steel . They are realised through machines used to remove metal shavings obstructing electroplate process. The mentioned guide, endowed with a sectioned geometrical structure, has a very important function : it is needed as static support.

The guide's mechanical resistance determines the application field of the actuator.

In fact, it can make it suitable to be used for heavy automatism, such as the transportation of cutting plasma apparatuses, as well as light

automatisms , such as the ones used for optic haulage. The bending and the fatigue resistances of a guide determines its qual ity and value.

For this reason, studyi ng a guide's profile is very important, especially the position of its stiffening ribs, which often help in containing the cross shifts of the motor truck. This is essential to reach a balance between mechanical resistance and the l ightness of the section made of the guide. It is important to consider that the guide sections are made through extrusion, which means they can't provide cross ribs.

Their purpose could be drawn out of in-between elements among the guide's modu les ( also known as junction rings ) as long as they are suitably resistant and economic. Given that, we come across another evidence. The mentioned common monolithic elements of assembly, which are part of the actuators, should have a resistance equal or superior to the one requested by the geometrical structure of the guide's section, otherwise they would be the weak point of the whole actuator. Therefore, the closing header at the extremities of the guide's section, the junction rings between different parts of the section and the motor truck itself should be given a lot of attention. They are, after all , the most expensive parts, a very high cost , due to the fact they are realised through the uti l ization of meta! shaving machines. An object of the present invention is to define a linear actuator wh ich

offers a resistance to the wear and tear (caused by its usage) superior to the one offered by actuators built with more common methods. Another object is to define a l inear actuator which can be resistant to bending and torsion, so that it can be suitable for carrying heavy weights.

Another object is to define a linear actuator presenting an efficiency of its junction parts and lasting longer than common actuators. Another object is to defi ne a linear actuator which can be built in such a way it can take up any configuration, back straight as well as curvy, even when running at a certain speed and with less resistant guide sections.

A further object is to define a linear actuator capable of being assembled easily by the buyer, thanks to the simplicity of its monol ithic elements. Finally, the aim is to realise an actuator at a low cost.

DISC LOS URE OF THE I NVENTI ON

These and further objects will be seen to be attained on reading the following detailed description i llustrating a linear actuator which is very pecu liar in the fact it has junction elements between one section and the other. These elements have a monol ithic structure which was realised through die casting techniques. The structure is fully fin ished and has highly precise proportions and can be subjected to even better, electroplating treatments.

BRIEF DESCRIPTIONS OF DRAWIN GS

The invention is illustrated by way of non-limiting exampl e i n the accompanying drawing, wh ich portrays, through exploded view, the actuators.

MODE FOR CARRYI N G O UT THE INVENTI ON

With reference to the mentioned drawing , a l inear actuator is made up of a guide G, a motor truck 4 and movement elements M.

The guide G, realised through a notorious aluminium extrusion technique, is joined to other guides G1 , G2, Gn...through monolithic joining elements 2 and it shows terminal elements at its extremities 3A, 3B. The joining monolithic elements 2 are real ised through pressure die casting techniques of light hard al loys or plastics. The invention includes a alloy zinc known as ZAMA ( aluminium 0, 1 í4%, copper 1 í3%, magnesium 0, 02í0, 06%, the rest is 99, 99% pure zinc) for the realisation of the joining monol ithic elements. Such ZAMA alloy gives the joining monolithic elements 2 a very high precision and very high structural rigidity which, in typical complex configuration of actuators, profitably offers minor torsional bending , which means less osci llation of the loads moved by the actuators. The terminal elements , which are made of ZAMA too, are particu larly resistant to time, particularly useful in points which are subjected to strain, such as assemblage threads.

A motor truck 4, made by numerous suitable and fit elements P, wil l regulate its position and link it to its movement elements M. The

drawing shows these elements as toothed belt. The mentioned motor truck was realised through pressure die-casting of ZAMA. This ensures an increased, excel lent durabil ity of the threads and the coupled sliding surfaces, as well as a high bending rigidity during the use of the actuator.

The use of ZAMA ₁ as well as other equivalent types of aluminium al loy, notably lowers costs and increases the mechanical resistance of the constitutional parts of the actuator: roughly between 24 kN/mm ² and 38 kN/mm ² . The highly precise execution offered by the ZAMA pressure die-casting all ow to produce already finished pieces , even when it comes to very complex shapes. This means the pieces won't need further processing. It is therefore advantageous to use known electroplate methods to harden their surface.

This will inevitably increase the mechanical resistance of al l parts and their antifriction, as well as their resistance to wear and corrosion.