Boring or penetrating the earth – With tool drive prime mover or above-ground mechanical... – Drive reciprocates tool
Patent
1992-10-09
1994-04-26
Britts, Ramon S.
Boring or penetrating the earth
With tool drive prime mover or above-ground mechanical...
Drive reciprocates tool
175296, E21B 100
Patent
active
053058410
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hammer device, preferably a down-the-hole hammer, including a casing, a piston, a drill bit and means for activating the piston to frequently strike the drill bit. The invention also relates to a piston and a drill bit per se.
In down-the-hole hammers the kinetic energy of the piston is transmitted by elastic waves through the drill bit and finally to the rock. However, said transmission is not carried out in an optimal way since the piston is not related to the drill bit in terms of length and mass. Also the drill bit does not cooperate with the rock in the best mode.
In prior art down-the-hole hammers very little attention has been paid to the adaption of the piston to the drill bit when said drill bit has a mass concentration at the end directed towards the rock.
The aim of the present invention is to further improve the energy transmission from the piston to the rock via the drill bit. This is realized by paying attention also to the distribution of the impedance in the piston and in the drill bit of a hammer device.
BRIEF DESCRIPTION OF THE DRAWINGS
Below an embodiment of a down-the-hole hammer according to the present invention is described, reference being made to the accompanying drawings, where
FIG. 1 schematically discloses the piston and the drill bit of a down-the-hole hammer according to the present invention;
FIG. 2 discloses the relationship between the applied force versus the penetration for a drill bit working a rock surface;
FIG. 3 discloses in a diagram the relationship between the degree of efficiency versus the relationship Z.sub.M /Z.sub.T ;
FIG. 4 discloses in a diagram the relationship between the degree of efficiency versus the relationship T.sub.M /T.sub.T ;
FIG. 5 discloses in a diagram the relationship between the degree of efficiency versus the parameter .beta.; and
FIG. 6 discloses a diagram showing the compressive and tensile stresses in the piston and the drill bit.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
In FIG. 1 the piston 10 and the drill bit 11 are schematically shown. As is evident from FIG. 1 the piston 10 and the drill bit 11 have a reversed design relative to each other.
The piston 10 has two portions 10a and 10b. The portion 10a has the length L.sub.M1 and the impedance Z.sub.M1 while the portion 10b has the length L.sub.T1 and the impedance Z.sub.T1. The drill bit 11 has two portions 11a and 11b. The portion 11a, i.e. the head of the drill bit, has the length LM.sub.2 and the impedance ZM.sub.2 while the portion 11b, i.e. the shaft of the drill bit, has the length L.sub.T2 and the impedance Z.sub.T2.
When stress wave energy is transmitted through pistons and drill bits it has been found that the influence by variations in the cross-sectional area A, the Young's modulus E and the density .rho. can be summarised in a parameter Z named impedance. The impedance Z=AE/c, where c=(E/.rho.).sup.1/2, i.e. the elastic wave speed. Any combinations of A, E and .rho. that corresponds to a certain value of the impedance Z gives the same result in respect of stress wave energy transmission.
It should be pointed out that the impedance Z is determined in a certain cross-section transverse to the axial direction of the piston 10 and the drill bit 11, i.e. the impedance Z is a function along the axial direction of the piston 10 and the drill bit 11.
Therefore, within the scope of the present invention it is of course possible that the impedances Z for the different portions 10a, 10b, 11a and 11b may vary slightly, i.e. Z.sub.M1, Z.sub.T1, Z.sub.T2 and Z.sub.M2 do not need to have a constant value within each portion but can vary in the axial direction of said portions 10a, 10b, 11a and 11b. In the practical design of the piston 10 and the drill bit 11 the provision of e.g. circumferential grooves and/or splines are quite frequent. Also the provision of e.g. a circumferential shoulder may be necessary.
It should also be pointed out that even if e.g. the portions 10a and 10b must have differ
REFERENCES:
patent: 3353362 (1967-11-01), Lubinski
patent: 3382932 (1968-05-01), Wise
patent: 3570609 (1971-03-01), Wise
patent: 3630292 (1971-12-01), Vincent
patent: 3903972 (1975-09-01), Bouyoucos et al.
patent: 4077304 (1978-03-01), Bouyoucos
patent: 4143585 (1979-03-01), Selsam
patent: 4166507 (1979-09-01), Rouyoucos et al.
Article: Int. J. Rock Mech. Min. Science & Geomech., vol. 23, No. 3, pp. 281-287 (1986), by B. Lundberg and L. G. Karlsson "Influence of Geometrical Design on the Efficiency of a Simple Down-the-Hole Percussive Drill".
Britts Ramon S.
Sandvik AB
Schoeppel Roger J.
LandOfFree
Hammer device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hammer device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hammer device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1706295