RU2330193C1 - Air cylinder - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: air cylinder is designed to move working tools. The air cylinder incorporates a rod with a piston arranged in a built-up casing incorporating a cylindrical sleeve, a through and blind covers with holes accommodating the unions feeding a compressed air and damping throttling devices, air cylinder covers and piston are jet moulded from thermoplastic polymer material with a glass-fibre filler. The rod, unions and damping throttling devices have special grooves receiving O-rings. The throttling devices represents a bolt with a small head with through threaded bore and an annular groove made on outer thread along with a hole made at the level of the said groove perpendicular to the bolt axis.

EFFECT: simpler design, higher reliability, smaller weight and better performances.

6 cl, 11 dwg

Description

The invention relates to the field of mechanical engineering, in particular to actuators that convert the energy of compressed gases (air) into rectilinear motion. Pneumatic cylinders are widely used to move working bodies in hoisting mechanisms, automatic machines, production lines, aircraft, etc.

Known pneumatic cylinder comprising a housing, end caps with openings for supplying and discharging a working medium, a piston with sealing elements placed in the housing with the formation of working cavities, a rod connected to the piston [1].

Also known is a pneumatic cylinder, comprising a housing with stepped caps, a piston with protrusions disposed in it, forming a cut-off cavity and an exhaust cavity with caps at the end of the stroke of the piston, communicated by the channel in the cover with the supply line (outlet) of the working medium [2].

Known pneumatic cylinder containing a sleeve, a piston that separates its internal volume with the formation of the rod cavity, the rod, the back cover, the front cover with a bore with a rubber spacer placed in it [3].

A disadvantage of the above known means is the complexity of the manufacture of end caps, in addition to each of them includes a guide sleeve, which requires additional costs for manufacturing and installation.

By technical nature, the closest to the proposed one is a pneumatic cylinder containing a working rod with a piston installed in a prefabricated housing including a cylindrical sleeve and end caps, each of which has an opening for a nozzle for supplying or discharging a working medium, a guide sleeve is installed inside one of the end caps to move the rod [4].

The end caps of the known device are manufactured by precision casting from an aluminum alloy, after casting they are tumbled in order to remove sharp burrs at the boundary of the half-mold connector. The disadvantage of this solution is the complexity of the manufacturing process requiring high precision base surfaces, because according to the technology, the part is not subjected to mechanical processing after casting. The front cover has a guide sleeve that requires installation. As a rule, the use of metal during casting forces, after casting a part, to carry out several heat treatment operations to relieve internal stresses. Also a significant problem in the manufacture of aluminum alloy end caps is the presence of micropores and gas inclusions after casting in them, which leads to the need for additional impregnation of them with various sealing compounds to prevent air leaks. In addition, increasing the thickness of the liner required to make a rigid connection with the end cap increases the weight of the pneumatic cylinder. All the described disadvantages lead to a complication of the design of the pneumatic cylinder, an increase in its mass, an increase in the time and complexity of manufacturing, as well as assembly and disassembly of the pneumatic cylinder.

The technical result is to simplify the design of the pneumatic cylinder, increase its reliability, simplify assembly and disassembly, as well as improve weight characteristics and other technical and operational qualities.

This result is achieved in that in a pneumatic cylinder containing a working rod connected to a piston, installed in a prefabricated housing including a cylindrical sleeve, blind and through covers with holes in which fittings and damping throttle devices are installed, according to the invention, the covers are made by injection molding from a thermoplastic polymer material with fiberglass filler (for example, glass-filled polyamide is a thermoplastic material that is 70% fiberglass). The through lid has an internal protrusion, the cylindrical surface of which serves as a guide for the rod, and the end surfaces are made in the form of rectangular teeth. On the cylindrical surface of the inner protrusion there is an annular groove into which the o-ring is installed. In addition, a damping throttle device, made in the form of a bolt with a reduced head, having a through threaded hole along the axis, as well as an annular groove on the outer side and an opening at the level of this groove, perpendicular to the axis of the bolt, and the degree of throttling is regulated by the depth of screwing the set screw into the through threaded bolt hole. The tightness during pairing of both metal and parts made of polymeric material (nozzle-cap, piston-rod) is ensured by the presence of annular grooves on the outer cylindrical surfaces of the metal parts with the sealing rings located in them.

The essence of the invention lies in the fact that the implementation of the new design of the pneumatic cylinder allows

- speed up the process of making caps;

- completely eliminate the mechanical and thermal processing of the product, the impregnation of the product with sealing compounds;

- to simplify the assembly process due to the design of the body of the through cover, which also acts as a guide sleeve, because the material from which the housing is made has antifriction properties, as well as due to the original one-piece piston mounting on the rod;

- facilitate the design due to the original shape and density of the material used;

- improve the lubrication of the rod and guide due to the presence of special teeth.

Figure 1 presents a section aa of the view of figure 2; figure 2 is a side view from the side of the blank cover of the pneumatic cylinder; figure 3 is a main view of a pneumatic cylinder, figure 4 is a main view of a through cover; in Fig.5, Fig.6 and Fig.7 presents options for section bB view of Fig.4; on Fig - mounting a threaded metal adapter for installing fittings in the housing of the cover using a threaded connection; Fig.9 - fastening a threaded metal adapter for installing the fittings directly into the housing of the cover as a reinforcement during injection molding; figure 10 - one-piece connection of the piston and rod; figure 11 - damping throttle device.

The pneumatic cylinder (Fig. 1) contains a working rod 1, one end of which is connected to a piston 2 located in the sleeve 3, a through 4 and a blind 5 covers, fastened with tie rods 6 and nuts 7. Each cover (figure 3) has a corresponding threaded metal adapters 8 and 9 for installing fittings for supplying compressed air and damping throttle devices 10 and 11. In each cover 4 and 5 (Fig. 1), a pair of o-rings 12 and 13 are installed. Each of the o-rings 13 is held by a metal locking ring 14 and four self cuts. In the through lid there is a sealing sleeve 15, which is also held by a metal ring 16 using self-tapping screws.

Both covers (FIG. 2 and FIG. 4) have stiffeners 17, due to which strength (safety factor 10 times) and lightness of the part (five times lighter than aluminum) are ensured. The design of the through cover (figure 5) provides an internal protrusion, the cylindrical surface 18 of which serves as a guide for the rod 1 (figure 1). The end surfaces of the inner protrusion (figure 5) are made in the form of rectangular teeth 19, due to which uniformity of compression (shrinkage) is ensured when the part cools down after casting. During operation of the pneumatic cylinder, the lubricant charged during assembly is held between the teeth 19, which provides better lubrication of the rod 1 with the through cover 4 (Fig. 1) and increases the service life of the whole product.

There are two more options for manufacturing an internal protrusion on the through lid. On the cylindrical surface (Fig. 5) of the inner protrusion 18 of the through cover 4 (Fig. 1), an annular groove is made in which a sealing ring 20 (Fig. 6) is installed, which increases the reliability of the product. Also, the role of the guide for the rod can only perform rectangular teeth 19 without surface 18 (Fig.7).

One or another manufacturing option is selected depending on the size of the manufactured pneumatic cylinder, the tested loads and the natural and climatic zone where the product will be operated.

The disadvantage of using parts made of polymer material is the fragility of threaded connections. To eliminate this drawback, blind and through covers are made with threaded metal adapters for fitting fittings. There are two possible installation options for threaded metal adapters.

The first option (Fig. 8) consists in the manufacture of blind and through covers with a threaded hole, into which a threaded metal adapter 21 is screwed in to fit the fittings. The threaded metal adapter has an external threaded surface, the tightness of the threaded connection is provided by the sealing ring 22. The threaded metal adapter is made of metal, for example, an aluminum alloy, and may have different internal threads depending on the fittings used.

During operation (installation-dismantling), the main load will be on the threaded fitting-threaded metal adapter (metal-metal) and the threaded metal adapter-case thinned or through cover (metal-polymer material) connection will be small, as a result, the reliability of threaded connections will increase , which will increase the life of the pneumatic cylinder as a whole.

The second option (Fig.9) provides for the installation of a threaded metal adapter 24 for mounting the fittings in the blind and through covers as valves for injection molding. During the casting process, a threaded metal adapter for fitting the fittings during heating has a greater degree of expansion than the polymeric material from which the blind and through covers are made, and when cooling together, a gap is formed between the threaded metal adapter for installing the fittings and the blind and through covers. Therefore, the mating cylindrical surfaces of the threaded metal adapter for installing the fittings 24 and the covers are made with annular grooves in which rubber sealing rings 23 are placed before casting, which ensure the tightness of the connection and the stability of the threaded metal adapter in the lid body.

According to the proposed design (figure 10), the piston 2 is cast directly onto the rod 1, and the rod at the junction with the piston is made with a cylindrical groove forming a stepped surface for permanent connection with the piston during injection molding, due to which the piston is held on the rod. Tightness of the coupling is ensured by the fact that annular grooves are made on the surface of the cylindrical groove of the rod at the junction with the piston, into which rubber sealing rings 25 are installed before filling the rod. This solution will reduce assembly time and facilitate the design due to the absence of fasteners.

For the blank and through caps of the pneumatic cylinder made of a polymeric material, the following design of the damping throttle device (Fig. 11), which is fastened using a threaded connection, is proposed. It is a bolt 26 with a reduced head, which has a through threaded hole along the axis, as well as an annular groove on the outside and an opening 27 at the level of this groove perpendicular to the axis of the bolt, and the degree of throttling is controlled by the depth of the set screw 28 screwed into the through threaded hole of the bolt. The surface of the annular groove forms a cavity 29 with the inner surface of the lid opening. The damping throttle device operates as follows. When the piston moves to the cover at a certain moment, the working cavity is cut off by the piston from the exhaust cavity, and the air is gradually bleed through a damping throttle device, thereby achieving smooth braking of the pneumatic cylinder. Air from the working cavity through the hole in the cover 30 enters the cavity 29, then through the hole 27 the air enters the space between the threaded surfaces of the bolt 26 and the set screw 28, after which it is vented through the hole 31 into the exhaust cavity of the pneumatic cylinder. The braking speed is controlled by the screwing depth of the set screw 28, the deeper, the greater the damping. The tightness of the threaded connection of the damping throttle device and the cover is provided by the rubber sealing rings 32.

The tightness between the bolt 26 with a reduced head and the set screw 28 is provided by a rubber sealing ring 33, while preventing the possibility of air leakage into the atmosphere, bypassing the exhaust cavity of the cylinder.

Thus, the proposed invention will simplify the design of the pneumatic cylinder, increase its reliability, reduce the complexity of assembly and disassembly, as well as improve weight characteristics and other technical and operational qualities.

Information sources

1. SU 1546733 A1, cl. F15B 15/14, dated 02.15.1988.

2. RU 2006684 C1, cl. F15B 15/22, dated June 17, 1991.

3. RU 2208717 C2, cl. F15B 15/14, dated 04.09.2001.

4. RU 2209351 C1, cl. F15 B 15/14, dated 04.03.2002.

Claims (6)

1. A pneumatic cylinder containing a working rod connected to a piston installed in a prefabricated housing including a cylindrical sleeve, blind and through covers with holes in which fittings and damping throttle devices are installed, characterized in that the blind and through covers and the piston are made of thermoplastic a plastic material with a fiberglass filler by injection molding, and the rod at the junction with the piston is made with a cylindrical groove forming a stepped surface for continuous Nogo compound with a piston when casting under pressure, penetrating the cover formed with an internal projection, the cylindrical surface of which serves as a guide for the stem, and the end faces are formed as rectangular teeth. 2. The pneumatic cylinder according to claim 1, characterized in that an annular groove is made on the cylindrical surface of the inner protrusion of the through cover, in which an o-ring is installed. 3. The pneumatic cylinder according to claim 1, characterized in that on the surface of the cylindrical groove of the rod at the junction with the piston are made annular grooves in which the sealing rings are installed. 4. The pneumatic cylinder according to claim 1, characterized in that the blind and through covers are made with threaded metal adapters for installing fittings. 5. The pneumatic cylinder according to claim 4, characterized in that the threaded metal adapters for installing the fittings are located in the blind and through covers as valves during injection molding, and the mating cylindrical surfaces of the adapters and covers are made with annular grooves in which the sealing rings are located. 6. The pneumatic cylinder according to claim 1, characterized in that the damping throttle device, made in the form of a bolt with a reduced head, having an through threaded hole along the axis, as well as an annular groove on the external thread and the hole at the level of this groove perpendicular to the axis of the bolt, and the degree throttling is regulated by the depth of screwing the set screw into the through threaded hole of the bolt.

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