GB2037630A

GB2037630A - Hydraulic drilling machine

Info

Publication number: GB2037630A
Application number: GB7940880A
Authority: GB
Original assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Current assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Priority date: 1978-12-22
Filing date: 1979-11-27
Publication date: 1980-07-16
Also published as: GB2037630B; PL219889A1; DE2855575C2; DE2855575A1; SU955869A3; JPS5585793A; FR2448622A2; PL122671B3

Abstract

Hydraulic drilling apparatus, particularly for rock drilling, in which a hydraulic feed motor (3) for the advance of the drill assembly (10, 11, 12) is supplied with oil under pressure by way of a supply line (13). A relief valve (18) in a relief line (16) leading to a tank (17) is controlled by the pressure in a flush line (31) supplying a flushing medium to the drill bit (12). The flushing medium flows through chambers on both sides of a membrane (25) the chambers being separated by a throttle. The valve body (19) is urged to a position opening the relief line (16) by a spring (30) to stop the feed motors (3) if there is a failure of the flushing medium supply through the supply line (32) or if the drill bit (12) becomes clogged preventing further flow of the flushing medium, either condition causing equalization of chamber pressures. The throttle (27) is in the membrane or housing and may be variable. <IMAGE>

Description

SPECIFICATION Hydraulic drilling machine The invention relates to a hydraulic drilling machine, in particular a rock drilling machine, having a feed motor to which is connected a hydraulic circuit having a supply line, and having a flush line for conducting a flushing medium to a drilling tool of the drilling machine.

In a known drilling machine of this type there is the danger of the so-called lock drilling if an increased drilling resistance occurs locally in the drill hole, e.g.

by a cave-in from the drilling hole wall or if the drilling hole becomes clogged up. In this case then the flushing medium can no longerflow in the drilling region and the tool locks up. This lock drilling can result in damage to the drilling tool, e.g.

breaking of the cutters. Furthermore, lock drilling is highly disadvantageous in as much as one often loses the drilling tool, and often the drill rod connected to the drilling tool as well, since the tool is held so fast that it can no longer be turned in any direction. In this case one has naturally lost, in addition, the drilling hole. The drilling rod often in this case extends rearwardly out of the bore hole a little and hinders further drilling in this region. In shot hole drilling the shot arrangement cannot then be maintained.

An object of the present invention is to improve the control and regulation of the feed of the drilling machine in relation to the flushing medium pressure.

In accordance with the present invention there is provided hydraulic drilling apparatus having a feed motor to which a hydraulic circuit having a supply line is connected and having a flush line for conducting flushing medium to a drilling tool of the drilling apparatus and wherein a valve is located in a line between the supply line of the feed motor and a tank, a valve body of the valve is connected by a rigid connecting element to a flexible membrane movable in a valve control chamber and dividing the chamber into first and second chamber parts, the membrane is urged by a spring into an end position opening the valve, and, the first chamber part is connected to a flushing medium supply line and the second chamber part is connected to the flush line, a conduit connecting the two chamber parts including a throttle.

The effective faces of the membrane can be selected to be of such a size that the valve is operated sensitively, quickly and accurately in relation to the flushing medium pressure. In particular, the valve is immediately and automatically opened by the spring in a mechanical manner if the flushing medium pressure falls away and becomes zero, so that flushing medium no longer flows. In this case the feed of the drilling machine must, in other words, be broken off as quickly as possible since otherwise the danger of a build up of rock dust or of lock drilling occurs. Also, in the case of a plugging up of the drill hole the flushing medium pressure rises very quickly in the flush line and is applied to the valve in such a way that it again opens so that the supply line for the feed motor is connected as quickly as possible with the return line to the tank.

In accordance with one embodiment of the inven tion the connecting element is coupled to the membrane so as to allow play in all directions. In this way, one obtains an arrangement which is particu larly easily operable and free of skew, which ensures a particularly sensitive operation of the valve body by way of the membrane.

In accordance with another embodiment of the invention the throttle is exchangeable. In this way the response characteristic of the membrane to the flush medium pressure if it is changing can be finely adjusted.

In accordance with a further embodiment of the invention conduit connecting the first and second chamber parts is a connecting line by-passing the membrane, the throttle being located in the connect ing line. The throttle can, in this way, be made readily accessible and exchanged for other throttles with different calibration.

A particularly simple construction is obtained if the throttle is, in accordance with the invention, arranged in a through-passage in the membrane constituting said conduit.

The invention will be further explained in relation to the exemplary embodiments illustrated in the accompanying drawings, in which: Figure 1 is a schematic representation of hydraulic drilling apparatus including hydraulic operating ele ments; Figure2 is a longitudinal section through another form of a valve arrangement; and Figure 3 is a detail of the valve arrangement according to Figure 2 in longitudinal section.

In Figure 1, a boom of a hydraulic drilling machine 2 is provided with a feed motor 3 constructed as a piston and cylinder unit whose piston rod 4 carries a reversing roller 5 for a flexible feed element 6, e.g. a chain. One end 7 of the feed element 6 is fixed to the boom 1 and the other end 8 is fixed to a slide 9 slidable over the boom 1. A drill motor 10 is mounted on the slide 9 and rotatably drives a drilling tool 12 by way of a drill rod 11.

The feed motor 3 is connected to a pressure oil supply and a tank by a supply line 13 and a return line 14 by way of a four-way/three position valve 15 and a relief line 16 leads from the supply line 13 to a tank 17 and includes a valve 18.

The valve 18 has a cylindrical valve body 19 having a central control groove 20. A rigid rod-like connect ing element 21 is fixed to the valve body 19 and has an end connected to a plate 22 located in a first chamber part 23 of a valve control chamber 24. A membrane 25 is connected to the plate 22 and divides the chamber 24 into the first chamber part 23 and a second chamber part 26.

A conduit connecting the two chamber parts 23 and 24 is in the form of a through passage in the membrane 25 in which a throttle 27 is arranged. The valve 19 and the chamber 24 are incorporated in a valve arrangement 28 having a housing 29 to which the periphery of the members 25 is fluid tightly fastened.

A spring 30, constructed as a compression spring, is arranged between the side of the membrane remote from the plate 22 and the housing 29 and urges the membrane 25 and thereby the valve body 19 into the position illustrated in Figure 1 in which the valve 18 is open and connected the supply line 13 of the feed motor 3 to the tank 17.

The drilling tool 12 can be supplied with a flushing medium, e.g. water or water and air, by way of a flush line 31 extending through the drill rod 11. The flush line 31 is connected with the second chamber part 26 while a flushing medium pressure supply line 32 opens into the first chamber part 23.

If no flushing medium flows in the flushing medium pressure supply line 32, the membrane 25 is urged by the spring 30 into the position illustrated in Figure 1 in which the valve 18 is open and the pressure oil is allowed to flow from the supply line 13 into the tank 17. The feed motor 3 is thus deactivated and, although the drilling tool 12 can rotate in the drill hole, it is not fed forward.

As soon, however, as flushing medium flows in the flushing medium pressure supply line 32, a higher flushing medium pressure builds up in the first chamber part 23 than in the second chamber part 26 because of the throttle 27. The pressure difference overcomes the compressive force of the spring 30 and pushes the membrane 25 downwardly from the position shown in Figure 1 so that the valve 18 is closed. If then the multi-way valve 15 has been operated to the right as seen in Figure 1 the supply line 13 is fed with pressure oil and the supply line 13 is fed with pressure oil and the feed motor 3 is operated in the feed direction.

If, the drill hole becomes plugged at any stage the pressure in the flush line 31 will increase so that the pressure on each side of the membrane is equalised and the spring 30 is again able to open the valve 18 to stop feed of the drill.

In the modified valve arrangement of Figures 2 and 3 the same parts as illustrated in Figure 1 have the same reference numerals.

Figure 2 shows one of the threaded bolts 33 with which the axially successive individual parts of the housing 29 are held together in the axial direction.

The valve body 19 is slid onto the rigid connecting element 21 at the right of Figure 2 and held in place by a split pin 34. The connecting element 21 is furthermore surrounded by ring seals 35 and 36 and a fluid leakage duct 37.

The plate 22 is surrounded, with play in all directions, by a guide ring 38 which is riveted through the membrane 25 to a stop plate 40 by means of rivets 39. The guide ring 38 and the stop plate 40 act together with shoulders 41 and 42 in the housing 29 to limit the travel of the membrane 25.

Spare throttles 44 are screwed into threaded bores 43 for use by substitution (as explained below) if a throttle of a different calibration is required.

As shown in Figure 3 the first chamber part 23 and the second chamber part 26 are connected with each other by way of a connecting line 45 by-passing the membrane 25 and having openings 46 and 47 respectively into the first chamber part 23 and the second chamber part 26. An element of the connecting line 45 is a threaded bore 50 in the housing 29 which runs transversely to a longitudinal axis 48 of a valve arrangement 49. The threaded bore 50 is closed on the outside by a screwed stopper 51 and receives therein a threaded throttle 52. The throttle can be exchanged as required for one of the reserve throttles 44 (see Figure 2) having a different calibration by removing the threaded stopper 51 exchanging the throttle and then replacing the stopper 51.

Claims

1. Hydraulic drilling apparatus having a feed motor to which a hydraulic circuit having a supply line is connected and having a flush line for conducting flushing medium to a drilling tool of the drilling apparatus and wherein a valve is located in a line from the supply line of the feed motor to a tank, a valve body of the valve is connected by a rigid connecting element to a flexible membrane movable in a valve control chamber and dividing the chamber into first and second chamber parts, the membrane is urged by a spring into an end position opening the valve, and, the first chamber part is connected to a flushing medium supply line and the second chamber part is connected to the flush line, a conduit connecting the two chamber parts including a throttle.

2. Drilling apparatus according to claim 1 wherein the connecting element is coupled to the membrane so as to allow play in all directions.

3. Drilling apparatus according to claim 1 or claim 2 wherein the throttle is exchangeable.

4. Drilling apparatus according to any one of claims 1 to 3 wherein the conduit connecting the first and second chamber parts is a connecting line by-passing the membrane, the throttle being located in the connecting line.

5. Drilling apparatus according to any one of claims 1 to 3 wherein the throttle is arranged in a through passage in the membrane constituting said conduit.

6. Drilling apparatus according to any preceding claim which is a rock drilling machine.

7. Rock drilling apparatus as hereinbefore described with reference to Figure 1 or to Figure 1 as modified by Figures 2 and 3 of the accompanying drawings.