GB2024057A - Pressure fluid actuating cylinder - Google Patents

Abstract

A pressure fluid operated rotating cylinder for the control of gripping implements of machine tools and the like, comprises a cylinder body (10), a plunger (14) slidable therein and separating therein cylinder chambers thereof. A control piston rod (15) is rigid with the plunger (14) and has one end thereof arranged for transmissive connection with the gripping implements. Duct means (20, 21) are provided in the cylinder body (10) for connection with a pressure fluid source and alternatively with a discharge. Safety valves (24, 25) are provided for maintaining constancy of fluid pressure within the cylinder and a flange member (22) closing the cylinder and facing one of the chambers. The cylinder body (10) and the flange member (22) have mutually mating surfaces. The flange member (22) has seats formed therein for housing the safety valves. <IMAGE>

Description

SPECIFICATION Pressure fluid operated rotating cylinder, for the control of machine tool gripping implements The present invention relates to a pressure fluid operated rotating cylinder for the control of gripping implements or spindles and selfcentering chucks, of machine tools, in general.

More particularly, the invention concerns pressure fluid operated cylinders provided with a cylinder body in rigid rotatory relationship with the gripping implement, a plunger axially mobile within the cylinder body but in rigid rotatory relationship therewith, a stem rigid with the plunger and which through a lever system controls the opening and the closing of the gripping implements jaws; and wherein the plunger separates, within the cylinder, two chambers which are selectively put in communication, through a distributor, with a source of fluid under pressure and a discharge to produce the double-acting operation of said cylinder.

Moreover, as known to the skilled in the art, the pressure fluid operated cylinders, as specified, may or may not be provided with safety valves, which are check valves suitable to assure, when they are provided, the constancy of the fluid pressure within the cylinder in order to avoid the decrease or drop of the jaws gripping pressure.

Pressure fluid operated cylinders of this type are disclosed in the Westgerman published patent applications 1.911.558, 2. 150.041 and 2.151.742.

The opportunity to install said valves depends from the gripping implement type to be controlled, being the presence of said valves absolutely required if the implement is provided with jaws having a long gripping stroke and a control mechanism of the reversible type. Vice versa such valves are superfluous if the implement is provided with jaws with a short gripping stroke and an irreversible type control mechanism.

The installation of said safety valves requires in the cylinders known at present time, a remarkably complicated structure so that the cylinders provided with said safety valves and those without them are structurally clearly differentiated so that, according to the present time techniques there are two separate categories of pressure fluid operated cylinders depending on the different use requirements.

This causes a remarkable economical drawback because, in cases where other parameters (such as rotational speed, dimensions, gripping power and similar) are left unchanged, constructions with radically different structures must be provided depending on whether the cylinder is or is not provided with safety valves.

The essential object of present invention is therefore to reduce said drawback by providing such an arrangement of the component parts which allows the transformation of a cylinder provided with safety valves, into a cylinder without them and vice versa, by the replacement of substantially one structural element, using essentially the same base structure and thereby appreciably reducing the manufacturing operations and costs.

The invention has further the object to provide a cylinder wherein it is possible to arrange that the above said transformation may be carried out in a simple and quick manner, so that according to the request, cylinders provided with safety valves and cylinders without said valves, may be arranged onto the common base structure.

Another object of present invention is to make it possible to provide a pressure fluid operated cylinder as specified wherein, when safety valves are installed in it, said valves are easily accessible, either for inspection or for repairs or replacements.

To attein said objects and others which will result from the detailed following specification, the present invention provides according to one aspect thereof a pressure fluid operated rotating cylinder for the control of gripping implements of machine tools and the like, having a cylinder body, a plunger slidable therein and separating therein cylinder chambers thereof, a control piston rod rigid with said plunger and having one end thereof arranged for transmissive connection with said gripping implements, duct means in said cylinder body for connection with a pressure fluid source and alternatively with a discharge, safety valves for maintaining constancy of fluid pressure within the cylinder and a flange member closing said cylinder and facing one of said chambers, said cylinder body and said flange member having mutually mating surfaces, characterized in that said flange member comprises seats formed therein for housing said safety valves, fastening means for removably and replaceably securing said flange member onto said cylinder body, and channel means extending from said valve means seats and having end channel portions opening at said mating surface of said flange member and wherein said duct means provided in said cylinder body have end duct portions opening at said mating surface thereof in alignment with said end channel portions.

Other particular features and advantages will result from the following detailed specification referred to the accompanying drawings, wherein: Figure 1 is a front view of the cylinder from the side of the removable flange; Figure 2 is an axial section, deviated along lines Il-Il of Fig. 1, showing the cylinder assembled with a flange provided with safety valves; and Figure 3 is a partial section similar to the preceding but showing the cylinder assembled with a flange having no safety valves.

In the drawings, numeral 10 generally indicates the cylinder body comprising a hollow hub 11 and a cylindrical bell 12 frontally open on the side facing the gripping implement (not shown). Reference numeral 13 indicates generally a fluid distributor which is slidably and sealingly mounted on hub 11 with the possibility of rotation about the hub which achsis. Within the cylindrical bell 12, a plunger 14 is sealingly slidable and rigidly engaged with a hollow piston rod 15 one end of which slides sealingly within the bored cavity of hub 11 and the other extends towards the gripping implement to actuate the mechanism, of known type, not shown, which controls the opening and closing of the jaws.

The plunger 14 separates within the bell 12, two chambers which, through the distributor 13, are selectively put into communication with a feeding duct 16 or with a discharge duct 17.

To that end, the distributor 13 is provided with annular ducts 18-19 communicating with corresponding channels as 20-21-20'21', formed in the wall of body 10 skirt; said channels extending in the hub 11 and bell 12 from which they open frontally.

Other channels and ducts may be provided in the hub 11 and in the distributor to complete the pressure fluid circuit and lands may be provided in the annular ducts 18, 19 of the distributor in order to allow fluid passage control by rotation of the distributor in different angular position. Since these elements are not essential for this invention and the principle of operation of a rotatory distribution is per se known a detailed description thereof has been omitted.

22 indicates a flange which closes frontally the bell 12 from the gripping implement side and the piston rod 15 passes sealingly through said flange 22.

As shown in Fig. 2, the flange includes a pair of axial seats to receive the safety valves K1 -K2 which communicate on one side with the cavity of the cylindrical bell, and on the other side, with channels 20-21-20'-21.' formed in the skirt of body 10, through radial channels 20a-21a, 20'a-21'a and frontal connection ducts 20b-21 b mating with the open end channel portions of said skirt channels; between the connection ducts and the open end channel portions sealing rings 23 of the O-ring type being interposed.

The operation of the device and of valves K1-K2 is known and not substantial for the present invention; said valves being of the type described in the published Westgerman and U.K. patent applications No. 2828609 and 2000455 A respectively of same Applicants. Such valves comprise a closing valve member 24 charged by a spring and pushed into opening direction by a small control piston 25, responsive to the differential pressure acting on its faces.

The flange 22 is removably engaged by bolts 26 to the bell 12 and may be easily removed or replaced by a different flange such as flange 27 having no safety valves K1-K2 but likewise sealingly crossed by the piston rod 15, as illustrated in Fig. 3.

Flange 27 is also provided with channels as 28-29 suitable to mate with the open end channel portions of the channels formed in the cylinder skirt and therefore it is immediately replaceable for flange 22 to allow the transformation of the cylinder provided with safety valves into one having no safety valves, since for both said cylinder types, the base structure is the same.

From the preceding specification and the drawings it appears evident that the valves K1-K2 result easily accessible and this makes easy the inspection and the replacement of the valves when they are provided on the cylinders.

Claims (7)

1. A pressure fluid operated rotating cylinder for the control of gripping elements of machine tools and the like, having a cylinder body, a plunger slidable therein and separating therein cylinder chambers thereof, a control piston rod rigid with said plunger and having one end thereof arranged for transmissive connection with said gripping implements, duct means in said cylinder body for connection with a pressure fluid source and alternatively with a discharge, safety valves for maintaining constancy of fluid pressure within the cylinder and a flange member closing said cylinder and facing one of said chambers, said cylinder body and said flange member having mutually mating surfaces, characterized in that said flange member comprises seats formed therein for housing said safety valves, fastening means for removably ans replaceably securing said flange member onto said cylinder body, and channel means extending from said valve means seats and having end channel portions opening at said mating surface of said flange member and wherein said duct means provided in said cylinder body have end duct portions opening at said mating surface thereof in alignment with said end channel portions.

2. A pressure fluid operated cylinder according to Claim 1, wherein the cylinder body comprises a hub and a cylindrical bell frontally open and a rotating distributor supported in said hub and wherein said cylindrical bell has said mating surfaces for closure by an interchangeable flange.

3. A pressure fluid operated cylinder according to Claim 1 ! wherein said flange member is an interchangeable flange having said channel means and wherein between said end channel portions and said end duct portions sealing rings of the O-ring type are provided.

4. A pressure fluid operated cylinder according to Claim 1, wherein said seats housing said safety valves in said flange member are advantageously oriented in the axial direction of the cylinder body.

5. A pressure fluid operated cylinder according to Claim 1, wherein said control piston rod sealingly crosses said flange member.

6. A pressure fluid operated rotating cylinder for the control of gripping implements of machine tools and the like, substantially as herein described with reference to the accompanying drawings.

7. Any novel element, or combination of elements, herein described and/or shown in the accompanying drawings, irrespective of whether the present claim is within the scope of, or relates to the same invention as, any of the preceding claims.