GB2322654A

GB2322654A - Percussion boring machine having an elastic separator

Info

Publication number: GB2322654A
Application number: GB9725429A
Authority: GB
Inventors: Alfons Hesse; Bernhard Kaufmann
Original assignee: Tracto Technik GmbH and Co KG; Tracto Technik Paul Schmidt Spezialmaschinen KG
Current assignee: Tracto Technik GmbH and Co KG
Priority date: 1996-12-03
Filing date: 1997-12-01
Publication date: 1998-09-02
Also published as: DE19650014C2; GB9725429D0; DE19650014A1; CA2223309A1

Abstract

A percussion boring machine has an axially movable piston (not shown) guided in a housing (1) by a control pipe (2), a elastic separator (4) between the housing (1) and the pipe (2) and a disc member (8) connecting the separator (4) to the pipe (2); the disc member being releasable so that in the event of damage the pipe (2) can be re-used. The disc member may be provided with a hose connection (10) and vent openings (14).

Description

1 "Percussion boring machine" 2322654 The invention relates to a

percussion boring machine comprising a striking piston which is axially movable in a housing and is controlled in its movement and control means with an elastic separator between the control means and the housing.

A percussion boring machine of this kind is known from German patent specification 38 33 882. In this machine an elastic separator is held in the housing by a circumferential radial front projection from the housing and at the back by a retaining ring which engages in a groove in the housing. On the control pipe the elastic separator is held by two circumferential projections: for assembly it is pushed on to the control pipe over the circumferential locking projection. The retaining ring is located in a groove in the housing. The production of the groove involves additional effort and expense.

In addition the elastic separator is provided with vent openings for the escape of the depressurised operating air. The weakening associated with this leads to the separator only having a limited ability to receive and absorb the high axial forces. In any event, however, a substantially larger separator is needed than in the case of a massive separator.

Finally disassembly of the separator is not possible without causing damage.

In the known percussion boring machine the compressed air hose is connected directly to the control pipe by means of a screw coupling. If the screw coupling should be damaged, the whole control pipe must always be replaced.

US patent specification 5 025 868 discloses a percussion boring machine the rear end of which is made up of a screwed-in stop for the striking piston and a closure

2 cap which are connected together by means of bolts. The rear stop is in the form of a ring screw thread both on the outside and in its bore. in the bore serves to receive a collar which connected to a connection for a compressed air design of this percussion machine requires an screws or and has a The thread is firmly hose. The expensive construction. A large number of different components are necessary. In addition the threaded parts are in direct contact with the housing of the machine. To prevent the screw connection coming loose due to the vibrations to which it is subjected the threaded parts are as a rule provided with a delicate fine screw thread and in addition are often stuck together with adhesive. For disassembly the adhesive joint must be loosened by heating, so that the possibility of damage due to heat cannot be excluded. If the connecting hose has to be replaced, the closure cap must always first be removed i.e. the adhesive joint must be broken - and the connecting hose then unscrewed. Before the machine is again ready for use, the connections must be put together again in the manner described above.

In addition this connection of the control pipe to the housing has the following further disadvantages. The control pipe must be fixed so as to run precisely centrally in the axial direction with respect to the machine housing and the striking piston, in order to avoid leakage between the striking piston and the control pipe and seizing and excessive wear between the control pipe and the striking piston. However, this is difficult to achieve with non centring screw connections.

It is an object of the invention to avoid the above mentioned disadvantages and in particular to facilitate the fitting of the elastic separator.

3 To this end, in accordance with the invention the elastic separator is fixed to the control means, preferably a control pipe, by means of at least one disk member which is connected releasably to, preferably screwed down to, the control means. On the housing side the elastic separator is held by two circumferential radial projections on the housing. The separator is easy to fit: it is first pressed together centripetally and folded and is then placed between the projections on the housing. The elastic separator is fixed by making the diameter of the disk member greater than the internal diameter of the elastic separator or of the rear end of the control pipe on which the separator can rest, so that in the firmly connected state a radial projection running all or part of the way round is formed. The disk member makes simple assembly possible, since the elastic separator is fixed by the easily releasable disk member. it is merely necessary to provide two circumferential radial projections in the housing and one such projection on the control pipe.

The disk member can be provided with a nozzle or a screw coupling to receive the compressed air hose. Should the screw coupling be damaged only the disk member need be replaced: the control pipe can be used again.

The elastic separator can take the form of a closed ring or of a segmental ring made up of half or quarter shells, which facilitate fitting it in the housing behind the projections. Furthermore the separator can also consist of two rings arranged concentrically or one behindthe other.

In order not to weaken the separator, the vent openings can also be located in a rear collar of the control pipe.

The separator or several separators then surround the control pipe collar.

4 The separator, the disk member, the control pipe or the housing can also be provided with a kind of mounting for fastening a traction cable.

A further possibility is to provide bores, grooves or projections in the elastic separator in order to facilitate the disassembly of the separator.

The invention will now be described in more detail, by way of example, with reference to examples illustrated in the drawings, in which:

Fig. 1 shows in longitudinal section a percussion boring machine having a connecting piece engaging loosely into the control pipe, Fig. 2 shows in longitudinal section a percussion boring machine having a connecting piece screwed into the control pipe, and Fig. 3 shows a section along the line III-III in Fig. 1.

In each case only the rear end of the percussion boring machine is shown. It comprises a housing 1 and a control pipe 2 which guides the striking piston (not shown here). Compressed air for controlling the movement of the striking piston is supplied to the control pipe 2 through a compressed air hose 3. The control pipe 2 is connected to the housing 1 by means of an separator 4. The separator 4 consists of elastic material and prevents the shocks and vibrations transmitted through the striking piston to the housing 1 from reaching the control pipe 2 without being damped. The separator 4 is located in the housing 1 by a front circumferential radial projection 5 and a rear, at least partially circumferential, radial projection 6. In a similar manner the separator 4 is fixed at the front end of the control pipe 2 by means of a collar 7 which may be connected releasably to the control pipe 2. At the rear end the elastic separator 4 is fixed by means of a disk member 8 releasably connected to the control pipe 2.

The disk member 8 is fixed to the control pipe 2 by means of screws 9. The disk member 8 is further provided with a pipe connection stub 10 to receive the compressed air hose 3. In event of damage it therefore suffices to replace the disk member 8 with the pipe connection 10: the control pipe 2 can be reused.

In the embodiment shown by way of example in Fig. 2 the disk member 8, which includes a tubular extension 12 provided with an external screw thread 11, is screwed into the control tube 2. As an aid to disassembly the separator 4 is in both cases provided with an opening 13 for inserting a tool. In addition in the rear part of the control pipe 2 which receives the separator 4 there are vent openings 14 running parallel to the axis through which the operating air acting on the striking piston leaves the percussion boring machine. As shown, the vent openings are at a greater radial distance from the machine housing than is the separator.

Alternatively the vent openings may extend through the separator 4.

The machine housing 1 is provided at its rear end with an external bevel, for example of conical shape.

In assembly, first of all the striking piston and then the control pipe 2 are inserted into the machine housing 1, and then the separator 4 is placed between the projections 5, 6. The control pipe 2 then only needs to be positioned and screwed down by means of the disk member 8 by means of straining screws 9. In the case of the embodiment shown in Fig. 2 this is done by screwing in the tubular extension 12.

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Claims

1. A percussion boring machine comprising a striking piston which is axially movable in a housing and has its movement controlled by a control pipe, and at least one elastic separator which is fixed by means of at least one disk member releasably connected to the control means.

2. A percussion boring machine according to claim 1, wherein the disk member is screwed on to a control pipe.

3. A percussion boring machine according to claim 1 or claim 2, wherein the disk member is provided with a hose connection.

4. A percussion boring machine according to any of claims 1 to 3, wherein the elastic separator consists of a closed ring.

5. A percussion boring machine according to any of claims 1 to 4, wherein the elastic separator ring is in the form of a segmental ring.

6. A percussion boring machine according to any of claims 1 to 5, wherein the elastic separator is a massive elastic separator.

A percussion boring machine according to any of claims 1 to 6, wherein the control pipe is provided with vent openings running parallel to the axis.

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8. A percussion boring machine according to claim 7, wherein the vent openings are arranged at a greater radial distance from the machine housing than is the separator.

9. A percussion boring machine according to any of claims 1 to 5, wherein the disk member is provided with vent openings.

10. A percussion boring machine according to any of claims 1 to 9, wherein the disk member is screwed on to the control pipe by means of straining screws.

11. A percussion boring machine according to any of claims 1 to 10, wherein the separator is disposed between a stop on the control pipe and the disk member.

12. A percussion boring machine according to claim 11, wherein the stop is a collar which is releasably connected to the control pipe.

13. A percussion boring machine according to any of claims 1 to 12, wherein the separator is arranged between two projections on the housing.

A percussion boring machine according to any of claims 1 to 13, wherein the housing is conically shaped at its rear end.