GB2313626A

GB2313626A - A telescopic prop for a hydraulic face support

Info

Publication number: GB2313626A
Application number: GB9710886A
Authority: GB
Inventors: Friedrich Wilhelm Dannehl
Original assignee: DBT GmbH; DBT Deustche Bergbau Technik GmbH
Current assignee: Caterpillar Global Mining Europe GmbH
Priority date: 1996-05-28
Filing date: 1997-05-27
Publication date: 1997-12-03
Also published as: PL320188A1; DE19621441C1; GB9710886D0

Description

A telescopic Prop for hydraulic face suipport The invention relates to a

telescopic prop for hydraulic face support with at least one cylinder tube, closed on the ground side, in whose pressure area a resective prop piston with a respective piston rod is driven by pressure fluid from outside in an axially sliding manner, whereby the annular space formed between the cylinder tube and the piston rod is closed by a respective flange shaped threaded ring screwed into the cylinder tube from above, which is fastened in a form fitting manner and on which the advancing prop piston comes to rest.

For the support of the canopies of hydraulic self-advancing support frames one or two telescopic props are employed. In the single stage version an extending prop piston can be pushed is upwards in a cylinder tube which is closed at the bottom. The annular space which is formed is closed by a threaded screw ring assembled from above, which is screwed into the cylinder tube using an external thread and thus forms a guide as well as a limit to the lifting of the prop piston. The prop piston of a two stage telescopic prop plunges into an inner cylinder tube, which forms the pressure area for the first, upper stage, and can be moved as a piston head in the outer cylinder tube which forms the pressure area of the second, lower stage. The annular spaces of the double telescopic prop are similarly closed by threaded rings.

The fine pitch screwed coupling of the threaded ring is secured by a formfitting connection, because the pulsating movements of the piston and the repeated impacts of the piston against the threaded ring exert a loosening effect on it. It has been previously proposed that a spring ring can be provided which is introduced above the threaded ring into an internal groove in the cylinder tube. In continuous use, however, the edges of the groove can corrode and be so damaged by the pulsating load of the prop, that they collapse and the spring ring beaks loose.

Reliable thread security can also be achieved by sinking a boring after the assembly of the prop, perpendicular to the axis, on the flange shaped collar of the threaded ring, right into the wall of the prop tube, into which a screw is inserted. This process is however tiresome and time-consuming, because the heavy prop has to be taken again after assembly to a drilling machine or a suitable drilling device. It has the added disadvantage is that the borings do not necessarily line up on assembly following a disassembly.

The aim of the present invention is to produce a durable, reliable, formfitting security device for the threaded ring of a prop, which can be produced during assembly with small expenditure of effort.

Accordingly the present invention is directed to a telescopic prop as described in the opening paragraph of the present specification, in which between the top bearing surface of the cylinder tube and the flange shaped extending collar of the threaded ring a respective deformable annular washer with in each case a special protrusion engages in a form fitting manner with limited width cut cuts, in both the cylinder tube and the threaded ring, and binds them together.

Advantageously the annular washer engages, by means of a curled strip in a rectangular shaped cut out in the collar of the threaded ring, whereby the curled strips are driven out from the annular washer with the aid of a shaped chisel to match the position of the cut outs and their width.

Preferably the annular washer engages, by means of a curled strip driven out from it, in a rectangular shaped cut out running downwards at an angle at the upper end of the cylinder tube.

The threaded ring is secured with a deformable annular washer, which is placed on the top of the cylinder tube during assembly and is screwed tight with the threaded ring. For the simple telescopic prop one metal annular washer, matched to the dimensions of the cylinder tube is sufficient. In production, cut cuts with a rectangular shaped cross section are to be provided in the flange shaped collar of the threaded ring and in the upper edge of the cylinder tube, which can be positioned at any point on the circumference. After the threaded ring has been screwed up, a specially provided chisel is used which is set into each of the cut cuts, and forms a curled strip from the material of the annular washer, which rolls into the cut out and lies with its edges on the side walls of the cut out.

In a preferred embodiment the annular washer is fastened using a cylindrically shaped pin, which is fastened to the underside of the washer, in a corresponding blind boring in the top side of the cylinder tube.

In a double telescopic prop it is useful to provide the securing annular washer for the upper stage with a pin, which engages in a corresponding axial blind boring on the top side of the inner cylinder tube.

The method of securing of the screw joint according to the present invention is simple and effective. The machining out of the rectangular shaped cut cuts on the threaded ring and the cylinder tube as well as the introduction of a boring into the cylinder tube is effected in production without great cost. The annular washer is also cost effective to produce. The expenditure of effort for driving out and bending the security strips using the shaped chisel in assembly is minimal. The same applies to the disassembly. The form-fitting jointing of the cylinder tube and the threaded ring is reliable and durable.

An example of a telescopic prop made in accordance with the is present invention is described below with reference to the accompanying drawings, in which:

Figure 1 shows a longitudinal section of a two stage telescopic prop according to the present invention; Figure 2 shows Section A from Figure 1 on a larger scale; and Figure 3 shows Section B from Figure 1 no a larger scale.

A double telescopic prop is positioned with a prop base 1 on a shoe of a self -advancing support frame (not shown). The prop base 1 closes off an outer cylinder tube 2 at its ground end. An inner cylinder tube 3, made with a smaller outside diameter, is introduced into the outer cylinder tube 2, whereby an annular space 4 arises between the two cylinder tubes 2 and 3. The inner cylinder tube 3 is similarly closed on the ground side and is constructed as a piston 5, which lies in a sliding manner on the inner wall of the outer cylinder 2. The annular space 4 is closed at its the top by a flange shaped threaded ring 6, screwed into the outer cylinder tube 2, which surrounds the inner cylinder tube 3 from the outside and on which the advancing piston 5 of the lower stage comes to rest.

In the inner cylinder tube 3 a piston 7 with a piston rod 8 of smaller diameter is driven in a sliding manner, which extends upwards out of the prop and supports a canopy of the selfadvancing support frame. An annular space 9 is formed between the inner cylinder tube 3 and the piston rod 8, which is closed at its upper end by a second flange shaped threaded ring 10 screwed into the inner cylinder 3, which again surrounds the piston rod 8 and on which the advancing piston 7 of the upper is stage comes to rest. The seals applied in various positions to seal the pressure stages are for simplicity referenced as 11.

The pressure areas of the two pressure stages (not shown) each lie under the piston surfaces of pistonS 7 and 5. The pressure fluid enters the pressure area of the lower stage via a pressure fluid connection 12 into the pressure area of the lower stage below piston 5 and via a base valve (not shown) which is set into an opening 13 in the base of the inner cylinder tube 3, into the pressure area of the upper stage below piston 7. The annular spaces 4 and 9 can be opened to the pressure fluid via the connection 14 to the outer cylinder tube 2 and the connection 15 to the upper end of piston rod 8 and further (not shown) connecting borings.

The threaded rings 6 and 10 are protected against unscrewing by deformable metal annular washers 16 and 17, which are positioned during the prop assembly from above on the tops of the outer cylinder tube 2 and of the inner cylinder tube 3. The two annular washers 16 and 17, which are matched in dimensions to the respective cylinder tubes 2 and 3, differ from each other also in that a pin 18 is fastened on the underside of annular washer 17, which engages in a corresponding blind boring 19 on the top edge of the inner cylinder tube 3.

Following the assembly of the threaded rings 6 and 10 they are fastened by the annular washers 16 or 17 in a form-fitting manner to their allotted cylinder tubes 2 or 3. For this purpose a rectangular cross section cut out 20 or 21 is provided at any point on the circumference in the flange shaped extending collar of each threaded ring 6 or 10. A further rectangular shaped cut out 22, which runs out at an angle downwards in the outer surface is milled into the upper end of the outer cylinder 2.

The fastening of the threaded ring 6 to the outer cylinder 2 is effected with the aid of a shaped chisel 23, which is bevelled into a wedge shape at one end and continues into an inwardly curved tip. The width of the shaped chisel 23 corresponds to the width of the cut outs 20, 21 and 22. This shaped chisel 23 is, as seen from Figure 2, placed with the bevel on the cut out 20 of the outer cylinder tube 2 onto the annular washer from below and driven with one or two blows into the cut out 20, whereby a spiral curled strip 24 is crimped out of the annular washer 16 which fills the cross section of the cut out 7 20.

The annular washer 16 is fastened to the outer cylinder tube 2, by placing the shaped chisel 23, as shown in Figure 3, with the bevel to the top, onto the annular washer 16 and driving the shaped chisel 23 into the annular washer 16. The strip 25 formed out of the annular washer 16 then engages in a form fitting manner with the cut out 22 in the cylinder tube 2.

The upper annular washer 17 is fastened to the inner cylinder tube 3 during assembly by the pin 18 engaging in the blind boring 19. The form fitting fastening to the threaded ring 10 is effected in the same way as described above for the threaded ring 6, using the shaped chisel 23. Following any disassembly of the prop, the annular washers 16 and 17 are replaced with new parts. The application of the invention is not is restricted to single and double stage telescopic props, but it can be used also for multiple lift props.

8

Claims

1. A telescopic prop for hydraulic face support with at least one cylinder tube, closed on the ground side, in whose pressure area a respective prop piston with a respective piston rod is driven by pressure fluid from outside in an axially sliding manner, whereby the annular space formed between the cylinder tube and the piston rod is closed by a respective flange shaped threaded ring screwed into the cylinder tube from above, which is fastened in a form fitting manner and on which the advancing prop piston comes to rest, in which between the top bearing surface of the cylinder tube and the flange shaped extending collar of the threaded ring a respective deformable annular washer with in each case a special protrusion engages in a form is fitting manner with limited width cut outs, in both the cylinder tube and the threaded ring, and binds them together.

2. A telescopic prop according to Claim 1, in which the annular washer engages, by means of a curled strip, in a rectangular shaped cut out in the collar of the threaded ring, whereby the curled strips are driven out from the annular washer with the aid of a shaped chisel to match the position of the cut cuts and their width.

3. A telescopic prop according to Claim 1 or Claim 2, in which the annular washer engages, by means of a curled strip driven out from it, in a rectangular shaped cut out running downwards at an angle at the upper end of the cylinder tube.

4. A telescopic prop according to Claim 1 or Claim 2, in which l- the annular washer is fastened using a cylindrically shaped pin, which is fastened to the underside of the washer, ina corresponding blind boring in the top side of the cylinder tube.

5. A telescopic prop substantially as described herein with reference to and as shown in the accompanying drawings.