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(11) | EP 2 570 678 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Rotary pneumatic actuator with inside protection and manufacturing process thereoff |
| (57) Pneumatic actuator wherein the actuator casing is made in plastic reinforced with
fibreglass and wherein a protective cylinder is disposed in the inner cavity of the
actuator which forms an integral part of the casing forming a single part, for which
purpose the cylinder is introduced in the mould during the manufacturing process before
injection of the plastic. Thanks to this configuration it resolves the problem of
wear of the toric elements housed inside the actuator cylinder.
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OBJECT OF THE INVENTION
[0001] The object of the present invention is a pneumatic actuator with inside protection, as well as the manufacturing process thereof, understanding an actuator to be a device capable of transforming hydraulic, pneumatic or electrical energy into the activation of a process with the purpose of generating an effect on an automated process.
[0002] The present invention is characterized in that the actuator is protected inside the casing, avoiding its wear and tear, as well as the process whereby the reinforcement incorporated forms a structural part of the actuator. Therefore, the present invention falls within the scope of actuators, particularly pneumatic actuators and those manufactured in plastic or with fibreglass.
BACKGROUND OF THE INVENTION
[0003] Currently, from the standpoint of the materials used to manufacture them, different types of actuators are known, such as:
- Actuators made in stainless steel: They are obtained by casting of the material and once the casing has been obtained, this is machined.
- Actuators made in aluminium: which, due to its properties of resistance and lightness, is a material to be considered for an actuator due to the high internal pressures whereto it is subjected. Nevertheless, aluminium has the problem that it corrodes when the air that enters the inner cylinder of the actuator is contaminated with particles. This corrosion weakens the aluminium forming porosities that make the actuator stop working.
- Actuators made with plastic. Additionally, plastic may contain fibreglass in order to increase its resistance to the actuator's high working pressures. In those actuators wherein the plastic has no additional material to give it greater resistance, this lack of resistance is compensated by considerably increasing the thickness of its walls.
[0004] Among the actuators manufactured with plastic, we can distinguish the following construction variants:
- Actuators solely made with plastic: Without fibreglass and without machining.
- Actuators made with plastic and with fibreglass as reinforcement, being later machined. This machining causes the migration towards the outside of fibreglass which is the cause of shortening the useful life of the torics housed in the internal channel or cylinder of the actuator.
- Actuators made with plastic and with fibreglass, machining and painting the inside of the channel or actuator cylinder, to avoid that the fibreglass which has migrated towards the outside can do so during the useful life of the actuator and cause the wear of the torics. This paint creates a layer which covers the fibreglass.
[0005] The object of the invention centres on plastic actuators with fibreglass, trying to resolve the problem of wear of the toric elements housed inside the actuator cylinder, for which a pneumatic actuator with inside protection has been developed such as that described below and is essentially included in claim one.
DESCRIPTION OF THE INVENTION
[0006] The object of the present invention is a pneumatic actuator with inside protection, designed for actuators made in plastic and particularly, although not in limiting manner, for those reinforced with fibreglass.
[0007] The reinforcement given to the actuators made in plastic consists of the disposal of an additional cylinder inside the channel of the actuator. This cylinder will protect the torics from the wear they may undergo on being in contact with the fibreglass, in the case of having used fibreglass as a reinforcement material of the plastic when manufacturing the actuators, or it will give a greater structural resistance to the actuator if it were only manufactured with plastic, avoiding having to increase its thickness to give it greater structural resistance.
[0008] In this way, the inner surface of the actuator casing is coated and protected by an additional cylindrical structure of a material more resistant than that of the material used in manufacturing the cylinder casing.
[0009] It is important to highlight that, as a consequence of the manufacturing process, the reinforcement cylinder is not an additional part added after manufacturing the actuator, instead it forms an integral part of the casing structure, forming a single body; to achieve this integrated combination the cylinder is introduced in the mould during the manufacturing process before injection of the plastic.
[0010] The additional protective cylinder may be of different materials: metal, such as stainless steel, plastic, which in a particular embodiment may be plastic extruded with fibreglass (the migration of fibreglass towards the outside would be avoided in the extrusion), it does not need machining and it can be of reduced thickness since the mechanical resistance must be exerted by the material the actuator casing consists of.
[0011] Therefore, the client's new proposal consists of obtaining a pneumatic actuator of plastic material with fibreglass in its casing, the inner channel whereof is protected by an additional cylinder which forms part of the actuator body, since it has been added in the injection process of the plastic in the mould to obtain the actuator casing, and that this actuator does not need machining.
EXPLANATION OF THE FIGURES
[0012] To complement the description made below and in order to aid towards a better understanding of its characteristics, a set of plans is attached to the present specification in the figures whereof, with illustrative and non-limiting character, the most significant details of the invention have been represented.
Figure 1 shows a perspective representation of two views of a pneumatic actuator.
Figure 2 shows a perspective representation of the protective cylinder.
EXPLANATION OF A PREFERRED EMBODIMENT
[0013] In light of the figures, a preferred embodiment of the proposed invention is described below.
[0014] Figure 1 shows in perspective the casing (1) of a pneumatic actuator, wherein all construction details can be observed. The actuator casing would be manufactured in plastic material reinforced with fibreglass which, during the machining process had migrated towards the outer walls.
[0015] Now, and with the aim of avoiding the wear of the torics or elements that move inside the casing due to the effect of the fibreglass migrated towards the walls, particularly the wall of the inner cavity, a protective cylinder is disposed that avoids the direct contact of the torics with the migrated fibreglass.
[0016] Figure 2 shows the protective cylinder (2) which is housed inside the actuator casing, which will have dimensions and construction characteristics that make it suitable for the intended purpose. This cylinder forms an integral or structural part of the casing, making the casing a single part although with two different materials, for which purpose, during the manufacturing process, before injection of the plastic material in the mould the protective cylinder (2) is disposed, for which reason once the plastic has been injected in the mould both materials form a single body.
1. Rotary pneumatic actuator with inside protection, characterized in that the actuator casing is made in plastic reinforced with fibreglass and in that a protective cylinder is disposed in the inner cavity of the actuator which forms
an integral part of the casing forming a single part.
2. Rotary pneumatic actuator with inside protection, according to claim 1, characterized in that the material used to manufacture the protective cylinder is metal.
3. Rotary pneumatic actuator with inside protection, according to claim 1, characterized in that the material used to manufacture the protective cylinder is stainless steel.
4. Rotary pneumatic actuator with inside protection, according to claim 1, characterized in that the material used to manufacture the protective cylinder is plastic.
5. Rotary pneumatic actuator with inside protection, according to claim 4, characterized in that the material used to manufacture the protective cylinder is plastic reinforced with
fibreglass wherein, in the extrusion, the migration of the fibreglass towards the
outside has been avoided.
6. Manufacturing process of the previously claimed rotary pneumatic actuator, wherein
the cylinder is introduced in the mould during the manufacturing process before injection
of the plastic.
Amended claims in accordance with Rule 137(2) EPC.
1. Rotary pneumatic actuator with inside protection, wherein the actuator casing is
made in plastic reinforced with fibreglass characterized in that a metal protective cylinder is disposed in the inner cavity of the actuator which
forms an integral part of the casing forming a single part.
2. Rotary pneumatic actuator with inside protection, according to claim 1, characterized in that the material used to manufacture the protective cylinder is stainless steel.
3. Rotary pneumatic actuator with inside protection, according to claim 1, characterized in that the material used to manufacture the protective cylinder is plastic.
4. Rotary pneumatic actuator with inside protection, according to claim 4, characterized in that the material used to manufacture the protective cylinder is plastic reinforced with
fibreglass wherein, manufactured by extrusion,
5. Manufacturing process of the previously claimed rotary pneumatic actuator, wherein
the metal protective cylinder is introduced in the mould during the manufacturing
process before injection of the plastic.