AU630914B2

AU630914B2 - Boring device

Info

Publication number: AU630914B2
Application number: AU49174/90A
Authority: AU
Inventors: Arno Pascher; Gunter Straub
Original assignee: SWISS INDUSTRIAL Co (AUSTRALIA) Pty Ltd
Current assignee: Joy MM Delaware Inc
Priority date: 1989-02-23
Filing date: 1990-02-06
Publication date: 1992-11-12
Anticipated expiration: 2010-02-06
Also published as: DE59000150D1; EP0384888B1; EP0384888A1; FI900834A0; AU4917490A; FI90277C; FI90277B

Description

COMMONWEALTH OF AUSTRAL- Patents Act 1952 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number Lodged Complete Specification Lodged Accepted Published 6I1 Priority 23 February 1989 0000 o.Oo Related Art 00 0 S 000 oooo'Name of Applicant 00 0 0 0 Address of Applicant 0 000 Actual Inventor(s) 0 00 00 0 0 0 G Address for Service 0 00 o 0 0 00.t0 S-I -G--HWIZERISCIHE INDTStRI GESELLCHfPT- GH-8-2-2-e u-h auseTnranr-Rirheinrfal-,s ss-Ce L)LL,: De 1 -fLO f- I-LLS ti. S u.2/i 7.

Gunter Straub and Arno Pascher F.B. RICE CO., Patent Attorneys 28A Montague Street BALMAIN NSW 2041 Complete Specification for the invention entitled: BORING DEVICE The following statement is a full description of this invention including the best method of performing it known to :uis/me:- This present invention refers to a rock boring device for the mining and tunnel-building industries in relatively soft rocks, where rotary percussion boring devices are of advantage and layers with different hardnesses are to be penetrated. Such devices have a rotary drive to rotate the boring bar, a percussion mechanism to strike the boring bar and a feed drive.

in case of known boring devices of this type usually the number of revolutions of the rotary drive, the frequency and the striking power of the percussion mechanism and the rate of feed 1'.9 can be adjusted. The adjustment depends from the type of rock :o which is to be bored and is based on empirical values. However, it happens often, that during the advancement various types of rocks have to be drilled through. In these cases the mechanisms Io 0 are adjusted to suit the hardest rock and are not the optimum I 0" for the softer layers- thereby leading to lower advancement capacities and increased tool wear.

A boring device t is 0000 o known from the Swiss patent A 657 664. This patent describes a percussive boring device with a rotary drive, a percussion mechanism and a feed drive. To increase the capacity of the 1: boring operation, the regulating pressure acting on a regulating valve is taken from the flow line of the feed drive. This enables a certain adjustment of the percussion frequency to the feed capacity. An optimum adjustment of the number of revolutions and of the percussion frequency on different rock hardnesses, however, cannot be achieved.

It is known from the US patent A-4 064 950 that it is advantageous to adapt the percussion frequency to suit the number of revolutions of the rotary drive. For this purpose the patent proposes to connect the percussion mechanism and the rotary drive in series. This solution, however, has not proved itself as an advantageous one, as in this case the percussion capacity is inversely dependent from the capacity of the rotary drive.

7 lb In the US patents A-4 246 973 and A-4 356 871 further boring devices are described, where the pressure to the percussion mechanism, the pressure to the rotary drive and the pressure to the feed drive are interdependent.

In case of the proposal in accordance with the European patent A-203 282 the percussion frequency is made dependent either from the torque of the rotary drive or the feed force.

In one broad form the present invention provides a boring device comprising: a rotary drive to rotate a boring bar; a percussion mechanism to strike the boring bar; a feed drive for the advancement of the rotary drive, percussion mechanism and boring bar; a first control mechanism to adjust the number of revolutions of the rotary drive and the percussion frequency of the percussion mechanism; as well as a second control mechanism to adjust the feed drive; characterised in that the second control mechanism has a pressure sensitive means which is adapted to sense an increase in a feed velocity of the feed drive, and that "the pressure sensitive means is connected with the first control mechanism in such a manner that, in case of an increased feed velocity, the number of revolutions of the rotary drive and the percussion frequency of the percussion mechanism will increase.

0 0 a devices are described, where the pressure to the percussion mechanism, the pressure to the rotary drive and th ressure to the feed drive are interdependent.

In case of the proposal in accordance ith the Europen patent A-203 282 the percussion frequen is made dependent either from the torque of the rotary dri or of the feed force.

The object of this 'rvention is to construct a boring device of the type menti ed in the introduction so, that an optimum uoco boring ca city could be achieved in different types of rocks.

o This ject is achieved by the characterising features of In the following an embodiment of the invention is explained 0 based on the drawing. Shown is: in Fig.1 a circuit of the boring device in accordance with the invention, in Fig.2 a section through a variable pressure regulator, and Fig.3 a section through a variation of the pressure regulator according to Fig.2.

The working components of the boring device are shown in Fig.1 schematically only. They consist of a rotary drive 1 to rotate a boring bar 2, a percussion mechanism 3 to strike the boring bar 0°o 2 as well as a feed mechanism 4 to advance the boring device 1, 2, 3. In addition, the device has a first control mechanism for adjusting the number of revolutions of the rotary drive 1 and the percussion frequency and the percussion power of the percussion mechanism 3, as well as a second control mechanism 6 to adjust the force and the speed of the feed.

The rotary drive 1 consists of a hydraulic motor 10 with a drive shaft 11, which is connected with the boring bar 2 so, that they cannot rotate relative to each other. The percussion mechanism 3 consists of a percussion cylinder 12, in which a percussion piston 13 is driven back and forth. By doing this the percussion piston 13 strikes against the rear end of the boring bar 2, preferably through an anvil (not illustrated). The rotary drive 1 and the percussion mechanism 3 are arranged in a common housing (not illustrated), which contains additionally a rotary valve 14 to regulate the percussion mechanism 3. The rotary valve 14 is driven by a transmission 15 through the shaft 11.

Due to this design the percussion frequency is exactly proportional to the number of revolutions of the rotary drive 1.

This has proved itself as extremely favourable for the adjustment of the revolutions and the percussion frequency for different rock hardnesses. The boring bar 2 executes a predetermined angle of rotation between two consecutive strikes, which [the angle] is independent from the 4wt of revolution.

To increase the percussion capacity and to keep the pressure o i.1 pulsation to the rotary valve 14 in the pressure line 16 and in S the return line 17 at a minimum, in these lines pressure Saccumulators 18 are arranged adjacent to the rotary valve 14.

Between the hydraulic motor 10 and the supply line 21, as well as the return line 22, a four/three-way valve 23 is connected, so that the motor 10 could be driven in clockwise and 0000 Santiclockwise directions. In both lines 24, 25 between the valve 23 and the motor 10 an adjustable pressure regulator 26 and a O non-return valve 27 are arranged connectedlparallel. The pressure regulators 26 act as flow regulators and are used for the adjustment of the base speed of the motor 10 for clockwise Sand anticlockwise revolutions. Normally the motor 10 rotates anticlockwise, while the line 24 is switched to the feed line 21. In this line 24 a proportional regulating valve 28 is connectedparallel to the valve 23 and the pressure regulator 26. The valve 28 opens against the force of a spring 29 proportionally to the pressure in its control line 30 and acts on the motor 10 through the by-pass line 31 with additional hydraulic oil, so that it will rotate faster proportionally with the pressure in the line The feed drive 4 comprises of a hydraulic cylinder 35 with a piston 36 and a piston rod 37, which is connected with the z housing of the rotary drive and the percussion mechanisms 1, 3 (not illustrated). Both chambers 38, 39 of the cylinder 35 are connected through a further four/three-way valve 40 with a further supply line 41 and return line 42. In the line 43 between the valve 40 and the feed chamber 39 a double pilotregulated pressure regulator valve 44, which is pre-loaded under an adjustable spring pressure. Both pilot pressures to the valve 44 are connected with both chambers 38, 39. Thereby, through the valve 44 during advancement the pressure on the boring bar 2 can be limited to a set value independently from the pressure in the chamber 38. The line 45 to the chamber 38 is connected through a three/two-way valve 46 in its first regulating position over an Sadjustable flow regulator 47 with the valve 40. The flow regulator 47 limits the feed velocity. When the piston 36 S returns, the oil flows through a by-pass 48, which at the same 0 time switches the valve 46 into the first position through a S pilot chamber 49.

In the second position of the valve 46 the line 45 is connected through a connecting line 55 with a variable pressure regulator 56. Its discharge 57 leads to the tank 58 through an adjustable 9e' pressure regulating valve 54. This regulating valve 54 maintains the start-to-operate pressure of the proportional control valve 28 even in case of a slight flow through the pressure regulator S 56. The control line 30 is connected to the line 55. The pressure regulator 56 is illustrated sectioned in Fig.2. In a cylindrical bore 61 of a housing 62 a plunger 63 is mounted in a So°o displaceable manner. The piston 63 penetrates through a sharpedged aperture 64 with a sliding fit. The aperture 64 divides the housing into two chambers; one inlet chamber 65 connected with the line 55 and an outlet chamber 66 connected with the line 57. In the chamber 66 a spring 67 presses against the face of the piston 63. The pre-tensioning of the spring can be adjusted by a screw 68. In the normal position the piston 63 rests on a cover 69 in the rear. The piston 63 has central symmetrical axial grooves 70 on its peripheral surface, which become deeper towards the rear. The cross-section of the grooves increases with the axial distance from that end of the piston 63 where the spring is situated. Consequently, the regulating cross-section increases steadily with the stroke of the 4 I_ II piston 63, which in turn is proportional to the pressure difference in the chambers 65, 66. The increase of the crosssection of the grooves 70 with the stroke of the piston 63 is appropriately designed so, that the impact pressure developed in the line 55 Is proportional to the flow-rate through the regulator valve 56. When the valve 28 also opens linearly, the increase of the number of revolutions of the hydraulic motor is proportional to the feed velocity.

Experiments have shown, that at almost linear dependence of the number of revolutions of the rotary drive 1 as well as of the frequency of the percussion mechanism 3 from the feed velocity of the feed mechanism 4 a feed capacity can be achieved which is at its optimum over a wide range of rock hardnesses. This is analogous with the already established linear coupling between the number of revolutions and the number of strikes of the percussion mechanism. The same advantageous relationship is connected with the third variable according to this invention.

When the operation commences for a hole to be bored, the valve 0ove 46 is in the illustrated neutral position. The pressure regulator valve 44 is adjusted for the optimum pressure to suit the expected hardest rock layer of the bored hole. Valve 26 is 0o0i also set to suit the expected hardest rock layer. In contrast, the flow regulator 47, which determines the pre-boring operation only, is set for the optimum feed velocity to suit the rock 0 which is to be bored first. As soon as the bore has been predrilled, the valve 46 is switched over. Nw Athe cutter head comes across softer rock during the boring, the feed velocity increases due to the constant pressure. Consequently, the impact pressure increases bIse4the variable pressure regulator 56, and thereby the pilot pressure on the regulating valve 28.

Additional oil is supplied to the motor 10 through the by-pass line 31, so that it will rotate faster and because of the transmission 15 the percussion frequency also increases.

Therefore the number of revolutions and the percussion frequency are adjusted automatically relative the feed velocity. At the same time this minimises the tool wear. With the increasing percussion frequency the energy of the individual strike also decreases, which is desirable in soft rock.

With the screw 68 the commencement of the connection of the bypass 31 can be adjusted. When an adjustment of the dependence from the number of revolutions is also desired, the spring characteristics of the spring 67' can be designed to be variable, as this is shown in Fig.3. The spring 67' is constructed here as a leaf spring. The free length of the spring 67' and consequently the spring characteristics can be adjusted with a slide 73. The slide 73 can be moved with the help of an adjusting screw.

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Claims

1. Boring device comprising: a rotary drive to rotate a boring bar; a percussion mechanism to strike the boring bar; a feed drive for the advancement of the rotary drive, percussion mechanisih and boring bar; a first control mechanism to adjust the number of revolutions of the rotary drive and the percussion frequency of the percussion mechanism; as well as a second control mechanism to adjust the feed drive; characterised in that the second control mechanism has a pressure sensitive means which is adapted to sense an increase in a feed velocity of the feed drive, and that the pressure sensitive means is connected with the first control mechanism in such a manner that, in case of an increased feed velocity, the number of revolutions of the rotary drive and the percussion frequency of the percussion mechanism will increase.

2. Boring device according to claim 1, characterised in that the percussion mechanism comprises a cylinder controlled by a valve, with a percussion piston, and the rotary drive comprises a hydraulic motor, the output shaft of which is connected with the valve by the means of a transmission.

3. Boring device according to claim 2, characterised in that the feed drive contains a hydraulic cylinder installation having first and second cylinder chamber opposite a piston, and that the pressure sensitive means is connected in a return flow path from the first cylinder chamber of the hydraulic cylinder installation through which return fluid selectively flows during the feed, the return fluid having an impact pressure which is dependent on the feed velocity.

4. Device according to claim 3, characterised in that an 0 e 8 adjustable, pilot-controlled pressure regulator valve is provided in a fluid line to the second cylinder chamber the pilot-control is effected by means of the pressure differential between the first and second cylinder chambers, whereby a feed force may be set which is independent from the feed velocity.

Device according to claim 3 or 4, characterised in that the pressure sensitive means is constructed as a variable pressure regulator, which produces a generally constant impact pressure independent from the flow quantity, and that the impact pressure acts on a control valve of the first control mechanism, while the control valve opens as the impact pressure increases.

6. Device according to claim 5, characterised in that in the supply line of the hydraulic motor a selector valve and an adjustable pressure regulator are provided, and that the control valve is arranged in a by-pass of the selector valve and of the adjustable pressure regulator.

7. Device according to claim 5 or 6, characterised in S 20 that the second control mechanism contains a further selector valve, which directs optionally the return flow from the first cylinder chamber through a further adjustable pressure regulator or through the variable pressure regulator.

8. Device according to one of the claims 5 to 7, characterised in that the variable pressure regulator contains a spring-loaded plunger which is actuated by the pressure differential between an inlet side and an outlet side thereof, which penetrates an aperture, and that in 30 the surface of the piston at least one groove is incorporated which diverges in the axial direction of the piston towards the inlet.

9. Device according to claim 8, characterised in that the pre-tensioning and/or the spring characteristics of the spring acting on the piston is adjustable. 8,- 9 A boring device as hereinbefore described with reference to th accompanying drawings. DATED this 16th day of September SWISS INDUSTRIAL COMPANY (AUSTRALIA) PTY LTD Patent Attorneys for the Applicant: F.B. RICE CO. 0000I. *040 4~ 4 0S 4I~t 4;I