CA1207197A - Method of controlling impact force and shock interval in drop hammers - Google Patents
Method of controlling impact force and shock interval in drop hammersInfo
- Publication number
- CA1207197A CA1207197A CA000422668A CA422668A CA1207197A CA 1207197 A CA1207197 A CA 1207197A CA 000422668 A CA000422668 A CA 000422668A CA 422668 A CA422668 A CA 422668A CA 1207197 A CA1207197 A CA 1207197A
- Authority
- CA
- Canada
- Prior art keywords
- core
- casing
- casings
- adjacent
- shock
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Placing Or Removing Of Piles Or Sheet Piles, Or Accessories Thereof (AREA)
Abstract
ABSTRACT
Method of controlling impact force and shock interval at a drop hammer of the type which has a core (10) and a number of casings (12, 14, 16, 19) arranged concentrically around the core. Between the core and the casings, spacings are arranged, and the core and the casings are interconnected alternatingly at one end and the other beginning at the upper end of the core. Between the lower end of the core and those ends of one or more casings, which are not permanently connected, a shock wave transferring connection is provided to short-circuit the path of the shock wave through the core and the casings.
FIG. 1.
Method of controlling impact force and shock interval at a drop hammer of the type which has a core (10) and a number of casings (12, 14, 16, 19) arranged concentrically around the core. Between the core and the casings, spacings are arranged, and the core and the casings are interconnected alternatingly at one end and the other beginning at the upper end of the core. Between the lower end of the core and those ends of one or more casings, which are not permanently connected, a shock wave transferring connection is provided to short-circuit the path of the shock wave through the core and the casings.
FIG. 1.
Description
~2~7~Lffl7 METHOD OF CONTROLLING IMPACT FORCE AND S~OCK INTERVAL IN DROP
HAMMERS
The invention relates to drop hammers for driving piles or the like into the ground, comprising a core which forms an impact surface at one end thereof, and casinys which are mutually spaced substantially concentrically around the core, the casing closest to the core being connected at one end there-of with the core at the other end thereof while other casings are interconnected alternatingly at one end and the other beginning at the other end of said casing closest to the core.
In the ideal case a drop h~mmPr should be subs-tantially of the same length as the pile to be driven down into the ground by means of the drop hammer. However, this is impractical and therefore the drop hAmmer is arranged as described above in order to obtain a long path of propagation for the shock wave while the drop hammer as suchhas a short length.
More particularly, the invention relates to the control of impact force and shock interval in a drop h~mmer of the type referred to above. It is desired to control impact force and shock interval or the reason that for driving a pile into the ground it may be necessary to have less force and longer shock instead of greater force and shorter shock in order that the pile will not wreck during driving.
An object of the invention is to make possible that impact force and shock interval are adapt~d to the ground conditions and the pile material in a favourable manner.
According to the present invention there is provided a drop hammer for driving piles or the like into the ground, the h~mm~r comprising an elongated core having at one end an impact surface, a plurality of casings, each casing having a first end and a second end opposite the first end with each first end being adjacent the impact surface of the core, the innermost casing being connected adjacent its second end to the end of the core opposite the impact surface, the innermost and next adjacent casing being connected together adjacent their first ends with the subsequent casings being connected together alternating between the second and first ends thereof, whereby each casing is attached to an adjacent casing, the drop hammer including a shock wave transferring connection element between the core, adjacent the impact surface thereof, and the adjacent end of at least the innermost one of the casings.
The invention will be explained in more detail below with reerence to the accompanying drawing, in which FIGURE 1 is a longitudinal cross-sectional view of a drop hammer of the type used in practising the method o the invention, and FIGURE 2 is a fragmentary longitudinal cross-sectional view similar to that in FIGURE 1 of the lower end of the drop hammer.
The drop hammer in FIGURE 1 comprises a cylindrical core 10 which forms an impact surface 11 at one end thereof.
At the other end a first casing 12 is permanently connected to the core 10 at 13, and this casing surrounds the core concentrical-ly spaced therefrom. Outside the casing 12 a second casing 14 is arranged concentrically with the core, and also the casings 12 and 14 are mutually spaced. The casing 14 is permanently connected to the casing 12 at the lower end of the drop hammer at 15, and it is surrounded by a third casing 16 which is concentric with the core and is spaced from the casing - 2a -;1;7~97 14. At 17 at the upper end of the drop hammer a permanent connection is provided between the casings 1 and 16 while said latter casing 16 at the lower end of the drop hammer is permanently connected at 18 to 'a fourth casing 19 spaced from the casing 16 and arranged concentrically with the core.
A shock wave generated in the core 10 when hitting a pile at the impact surface 11, will propagate through the core to the upper end thereof and:via the connection 1~ at 13 to the casing 12, then ~ownwards through said latter casing and:v~ the.connection at-15.upwards through the casing 14 from which the shock wave will pass to the casing 16 via~the connection at 17 to propagate d~n. :
the casing 16 and then via the connection 18.upwards through the casing 19. The shock wave then will be reflected back along the path described to the impact surface 11.
In order to shorten ~he propagation path of the shock wave there is pro~ided by the method according to the invention a shock'wave transferring connection, "short circuiting",between the core and a voluntary number of casings. Thus, a short rircuiting is shown in FIG. 1 between the core 10 and the second casing 14 and it is provided by means of a ring 20 at the lower end of the drop hammer such that the shock wave ~ill propagate ~rom the impact surface 11 via the ring 20 and the connec-tion 15 dlrectly to the casin~ 14 so as to follow there-after the same path as ~efore to the upper end of the cas-ing 19, This shortening of the path of the shock wave provides a greater impact force; however, the shock inter-val will be shorter.
The ~mpact force can be furthe'r increased by short circujting several casings as is sho~n in F~G~ 2 wherein a ring 20' forms a shock wave transferring connection from the core la directly to the outermost casing 19, .
12~ 97 which means that the shock interval will be still shorter than in the arrangement shown in FIG. 1. By using rings of different sizes in order to provide a shock wave transferring connection between the core and the casings at the ends where permanent connection is not arranged, it is possible to adapt impact force and shock interval to the prevailing conditions, i.e. to the ground nature and the material of the pile to be driven down into the ground.
The rings 20 and 20', respectively, can be attached in different manners by ~eans of scre~ connections, clamp connections or the like. It is important, however, that the r;ng is securely attached while it is at the same time possible to replace easily the ring.
E.g. the core 10 can form a shoulder facing downwards at the lower end of the core, said shoulder surrounding the impact surface 11 axially spaced therefrom. The ring 20 or 20' can be attached to the shoulder by means o~
screws which are passed through the ring to engage threaded 6Ores in the shoulder. The ring can also be attached to the casing 15 or the casing 19 as the case may be, by simllar screw connections~
,
HAMMERS
The invention relates to drop hammers for driving piles or the like into the ground, comprising a core which forms an impact surface at one end thereof, and casinys which are mutually spaced substantially concentrically around the core, the casing closest to the core being connected at one end there-of with the core at the other end thereof while other casings are interconnected alternatingly at one end and the other beginning at the other end of said casing closest to the core.
In the ideal case a drop h~mmPr should be subs-tantially of the same length as the pile to be driven down into the ground by means of the drop hammer. However, this is impractical and therefore the drop hAmmer is arranged as described above in order to obtain a long path of propagation for the shock wave while the drop hammer as suchhas a short length.
More particularly, the invention relates to the control of impact force and shock interval in a drop h~mmer of the type referred to above. It is desired to control impact force and shock interval or the reason that for driving a pile into the ground it may be necessary to have less force and longer shock instead of greater force and shorter shock in order that the pile will not wreck during driving.
An object of the invention is to make possible that impact force and shock interval are adapt~d to the ground conditions and the pile material in a favourable manner.
According to the present invention there is provided a drop hammer for driving piles or the like into the ground, the h~mm~r comprising an elongated core having at one end an impact surface, a plurality of casings, each casing having a first end and a second end opposite the first end with each first end being adjacent the impact surface of the core, the innermost casing being connected adjacent its second end to the end of the core opposite the impact surface, the innermost and next adjacent casing being connected together adjacent their first ends with the subsequent casings being connected together alternating between the second and first ends thereof, whereby each casing is attached to an adjacent casing, the drop hammer including a shock wave transferring connection element between the core, adjacent the impact surface thereof, and the adjacent end of at least the innermost one of the casings.
The invention will be explained in more detail below with reerence to the accompanying drawing, in which FIGURE 1 is a longitudinal cross-sectional view of a drop hammer of the type used in practising the method o the invention, and FIGURE 2 is a fragmentary longitudinal cross-sectional view similar to that in FIGURE 1 of the lower end of the drop hammer.
The drop hammer in FIGURE 1 comprises a cylindrical core 10 which forms an impact surface 11 at one end thereof.
At the other end a first casing 12 is permanently connected to the core 10 at 13, and this casing surrounds the core concentrical-ly spaced therefrom. Outside the casing 12 a second casing 14 is arranged concentrically with the core, and also the casings 12 and 14 are mutually spaced. The casing 14 is permanently connected to the casing 12 at the lower end of the drop hammer at 15, and it is surrounded by a third casing 16 which is concentric with the core and is spaced from the casing - 2a -;1;7~97 14. At 17 at the upper end of the drop hammer a permanent connection is provided between the casings 1 and 16 while said latter casing 16 at the lower end of the drop hammer is permanently connected at 18 to 'a fourth casing 19 spaced from the casing 16 and arranged concentrically with the core.
A shock wave generated in the core 10 when hitting a pile at the impact surface 11, will propagate through the core to the upper end thereof and:via the connection 1~ at 13 to the casing 12, then ~ownwards through said latter casing and:v~ the.connection at-15.upwards through the casing 14 from which the shock wave will pass to the casing 16 via~the connection at 17 to propagate d~n. :
the casing 16 and then via the connection 18.upwards through the casing 19. The shock wave then will be reflected back along the path described to the impact surface 11.
In order to shorten ~he propagation path of the shock wave there is pro~ided by the method according to the invention a shock'wave transferring connection, "short circuiting",between the core and a voluntary number of casings. Thus, a short rircuiting is shown in FIG. 1 between the core 10 and the second casing 14 and it is provided by means of a ring 20 at the lower end of the drop hammer such that the shock wave ~ill propagate ~rom the impact surface 11 via the ring 20 and the connec-tion 15 dlrectly to the casin~ 14 so as to follow there-after the same path as ~efore to the upper end of the cas-ing 19, This shortening of the path of the shock wave provides a greater impact force; however, the shock inter-val will be shorter.
The ~mpact force can be furthe'r increased by short circujting several casings as is sho~n in F~G~ 2 wherein a ring 20' forms a shock wave transferring connection from the core la directly to the outermost casing 19, .
12~ 97 which means that the shock interval will be still shorter than in the arrangement shown in FIG. 1. By using rings of different sizes in order to provide a shock wave transferring connection between the core and the casings at the ends where permanent connection is not arranged, it is possible to adapt impact force and shock interval to the prevailing conditions, i.e. to the ground nature and the material of the pile to be driven down into the ground.
The rings 20 and 20', respectively, can be attached in different manners by ~eans of scre~ connections, clamp connections or the like. It is important, however, that the r;ng is securely attached while it is at the same time possible to replace easily the ring.
E.g. the core 10 can form a shoulder facing downwards at the lower end of the core, said shoulder surrounding the impact surface 11 axially spaced therefrom. The ring 20 or 20' can be attached to the shoulder by means o~
screws which are passed through the ring to engage threaded 6Ores in the shoulder. The ring can also be attached to the casing 15 or the casing 19 as the case may be, by simllar screw connections~
,
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A drop hammer for driving piles or the like into the ground, said hammer comprising an elongated core having at one end an impact surface, a plurality of casings, each casing having a first end and a second end opposite said first end with each first end being adjacent said impact surface of said core, the innermost casing being connected adjacent its second end to the end of said core opposite said impact surface, the innermost and next adjacent casing being connected together adjacent their first ends with the subsequent casings being connected together alternating between said second and first ends thereof, whereby each casing is attached to an adjacent casing, said drop hammer including a shock wave transferring connection element between said core, adjacent said impact surface thereof, and the adjacent end of at least the innermost one of said casings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000422668A CA1207197A (en) | 1983-03-02 | 1983-03-02 | Method of controlling impact force and shock interval in drop hammers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000422668A CA1207197A (en) | 1983-03-02 | 1983-03-02 | Method of controlling impact force and shock interval in drop hammers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1207197A true CA1207197A (en) | 1986-07-08 |
Family
ID=4124688
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000422668A Expired CA1207197A (en) | 1983-03-02 | 1983-03-02 | Method of controlling impact force and shock interval in drop hammers |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1207197A (en) |
-
1983
- 1983-03-02 CA CA000422668A patent/CA1207197A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |