WO1996015349A1

WO1996015349A1 - A method to drill a hole with a hammer, the hammer and a joint between hammer and drill bit holder

Info

Publication number: WO1996015349A1
Application number: PCT/FI1995/000625
Authority: WO
Inventors: Valto ILOMÄKI
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-11-11
Filing date: 1995-11-13
Publication date: 1996-05-23
Anticipated expiration: 1997-05-11
Also published as: AU3873495A; FI945965A0

Abstract

The invention relates to drilling a hole in soil or rock using a drilling tool driven by a hammer, which method and hammer use the hammer to drill especially by a large-diameter drill bit (23). In this method a part supporting the bit holder, for instance a guide bushing (22) is fastened to the hammer casing and the diameter size of the holder portion in the bushing is increased substantially with regard to the impact-receiving face diameter of the holder by dimensioning the said guide bushing so that it can be easily fixed on the outer surface of the hammer casing or it is made an expanded extension of the said casing.

Description

A METHOD TO DRILL A HOLE WITH A HAMMER, THE HAMMER AND A JOINT BETWEEN HAMMER AND DRILL BIT HOLDER

The invention relates to a hammer, by means of which a drill bit furnished with a special bit holder is hammered on drilling a hole in soil or rock, a method to execute drilling with a large- diameter bit and a joint between the hammer and the holder.

Previously known is a construction as per figutre 4, where a tubular, the holder supporting part 8, is fastend by a thread to the inner surface of the hammer casing. The inner diameter of bushing 8 is slightly smaller than the diameter of the percus¬ sion piston. By such a design the holder becomes weak, especi¬ ally when the locking groove makes it ever lighter. Likewise, the strength of the holder is diminished from the inside by a scavenging duct in the holder center. The holder weaknesses become apparent when the holder diameter grows. When the edge of the bit encounters a hard surface, for instance rock, in the bit a torque motion, which can easily break the holder neck, is generated. Anyhow, bits can be driven by hammers if the bit diameter exceeds manyfold the size of the percussion piston 2 diameter. Accordingly, the holder construction and the support bushing design 8 as per figure 4 are not reliable.

In this invention a significant improvement of these disadvant¬ ages is achieved and the invention is characterized in what is presented in the enclosed patent claims.

The advantage of this invention is that the location and the way of fastening the support holder more toward the hammer outer circle from its conventional location and engagement allow a construction of quite another strength category. Starting from its impact-receiving face, the holder diameter can be substant¬ ially enlarged without any weakening cross grooves. The holder becomes even shorter than the previous, for a corresponding bit diameter designed holders, since the holder expands immediately in the hammer front, for instance to the rate of the hammer outer diameter. When the supporting face of the holder is made larger than the hammer diameter, it is possible to install from the hammer outside oblong gliding and locking means on the sup¬ porting face itself, whereby the holder can be locked and opened even in the drill hole.

Furthermore, the solution according to this invention allows enlargement of the through hole in the holder center without weakening the holder strength. The hole can be enlarged so that the scavenging air to the bit as well as the return air can be conveyed most suitably through the holder in using coaxial piping.

In the following the invention is disclosed with reference to the enclosed drawings, where

Fig. 1 - 3 show attachment principles of the support bushing.

Fig. 4 shows a previously known attachment of the support bushing to the hammer.

Fig. 5 shows a cross-section of the bit, the holder and holder attachment to the hammer.

Fig. 6 shows a cross-section of the holder and holder attachment to the extension of the hammer casing

Figures 1 - 3 illustrate different principles how the support bushing 3 can be attached to the hammer casing or formed from the hammer casing. A threaded joint or a flange joint with screws can be used and the casing can be expanded or extended in order to form the bushing. Percussion piston 2 can be in the casing.

Figure 5 illustrates a support bushing 12 attached on the per¬ cussion machine casing 13 with a thread. Percussion piston 14 is in the casing and glides also with regard to the holder by means of an intermediate bushing 17 that works as a packing. The holder can move a limited distance in bushing 12. The distance is 50 mm, for instance, which is a sufficient travel between holder and bushing so that the holder does not hit the block stops in the bushing but the bit hits the soil it encounters. In corresponding spots on bushing 12 inner face and holder outer face there are gliding means, axial grooves and ridges, so that rotation is transmitted from bushing to holder. In the figure the holder has grooves 25, whereby there must be ridges in the bushing, which in the stage of installation glide into grooves 25 and by mutual rotation of bushing and holder, the ridges in the bushing are turned to the back of noses 26 that cut off the the grooves in the same manner as a bayonet joint From the out¬ side of the casing locking pins 27 are then pushed through holes in the bushing rear end into the joint itself, where the pins prevent the holder from turning so as to open the bayonet joint. Pins 27 work also as gliding means for the mutual axial movement of holder and bushing. Parts 18 are packings and, simultaneous¬ ly, gliding faces as well. In the bayonet joint necessary axial clearance is arranged, which must be done for the holder because of the travel of percussion.

The figure shows how coaxial channelings 15 and 19 and piping 16 are loosely arranged in the holder and also taken through the piston but not affecting the strength of the holder.

The tubular locking pin 27 illustrated in the figure can be secured by a side screw on its place. All locking pins can also be pulled out at a time by some arrangement and the joint open¬ ed, even with the equipment in the drill hole.

Figure 6 is another version of the holder support bushing 22 fastened on the casing by a threaded joint. In this case the bushing inner face has gliding grooves only and the holder 24 face has counter grooves. A ring 21 has been left on the bushing 22 inner face working as a stopper. Holder 24 can be pushed into bushing 22 and pulled out when so wanted. This is made possible by the construction of locking ring 20, which is made of two parts, whereby on pulling holder 24 slightly to the left from the position in the figure, the locking ring halves can move outward into the groove in bushing 22. The holder can then move furhter to the left and out from the bushing, since the collar in the in the impact-receiving end can pass the halves of lock¬ ing ring 20.

The joint and the expansion of the holder according to this invention are especially well adaptable to drilling of large holes, for instance holes with a diameter over 300 mm, whereby the hammer follows the bit immediately and advances in the hole behind the bit.

The lockings of the holder can be modified in many ways and the invention is not restricted to embodiments as per the presented examples but many modifications are possible within the limits of the inventional concept determined in the patent claims.

Claims

PATENT CLAIMS

1. A method to drill a hole in soil or rock with a drilling tool (6) driven by a hammer (1), by which method the hammer (1) is used to drill especially with a large-diameter bit (6,10,11,23) and the hammer (1) designed to travel in the hole immediately behind the bit, characterized in that in this method a part supporting the bit holder, for instance a guide bushing (3,12, 22), is fastened to the hammer (1) casing and the diameter size of the holder portion (4) in the bushing is increased substant¬ ially with regard to the diameter of the impact-receiving face of the holder by dimensioning the said guide bushing so that it can be easily fixed on the outer surface of the hammer casing or it is made an expanded extension of the said casing.

2. A method according to patent claim 1, characterized in that the diameter of holder portion (4) is dimensioned substantially in level with casing (13) or exceeding it.

3. A joint between holder portion (5,24) of the hammering drill bit and hammer (1), which is advancing in the hole behind the bit, over which joint the hammer rotates the holder fastened to this joint from its neck portion (4), characterized in that the joint includes one or more holder-supporting guide bushings (3,12,22) which are fixed to the hammer extending forward from its casing (13) or in level with its outer surface, and the diameter of the joint surface between said bushing and holder is substantially larger than the diameter of the percussion piston (2,14).

4. A joint according to patent claim 3 characterized in that it includes means transmitting rotation from bushing to holder, for instance axial grooves with corresponding counter parts, which restrict the mutual axial movement of bushing and holder.

5. A hammer (1) that produces percussions to the holder (5,24) of the hammering bit drilling a hole in the soil and advances in the hole immediately behind the bit and by means of which the bit-rotating force is transmitted to the bit and which hammer supports the bit by means of a holder attached to the bit, the said holder being supported from its neck portion by a support part fastened to the hammer characterized in that the outer sur¬ face of the hammer casing is expanded forward or to the surface of the casing, most suitably its outer surface, a bushing (3,12, 22) is fixed to support the holder, due to which the diameter of the said bushing is substantially larger by the holder than the diameter of the percussion piston (2,14).

6. A hammer according to claim 5 characterized in that the bushing is fastened by a threaded joint on the casing of the hammer.

7. A hammer according to claim 5 characterized in that the bushing is fastened by a flange joint to the front edge of the hammer casing .

8. A hammer according to any of the above patent claims 5 - 7 characterized in that the diameter of the joint surface between holder (4,24) and bushing is larger than the diameter of the hammer casing allowing installation of power transmitting or locking means (27) from the outside of the casing to correspond¬ ing spaces arranged in the said joint surface.

9. A hammer according to any of the above patent claims 5 - 8 characterized in that there is between holder and bushing a bayonet joint allowing, restrictively, their mutual axial movement and that opening of the joint is prevented by locking means (27), which can be pushed into the joint to prevent the joint from turning open and the locking means (27) function as gliding surface of the axial movement.

10. A hammer according to any of the above patent claims 5 - 8 characterized in that the axial movement between holder (24) and bushing (22) is restricted by a two-piece locking ring (20) in the holder cross-groove, for which ring a location between said parts is arranged enabling it to move to the outer groove circle and release the restriction of the axial movement.