US2787123A - Pneumatic driving hammers - Google Patents

Description

J. A. M. DELVAUX 2,787,123

4 Shets-Sheet 2 PNEUMATIC DRIVING HAMMERS A ril 2, 1957 Filed -lvlarch 23, 1954 April 9 J. M. DELVAUX 2,787,123

PNEUMATIC DRIVING HAMMERS Filed March 23, 1954 4 Sheets-Sheet 3 a Q J April 2, 1957 J. A. M.- DELVAUX 2,787,123

PNEUMATIC DRIVING HAMMERS Fild March 23. 1954 4 Sheets-Sheet 4 PNEUMATIC DRIVENG HAMMERS Jules Arnold Marie D'elvaux, Tilleur, Belgium, assignor to Compagnie Internationale des Pienx Armes Frankignoel, Seciete Anbnyme, Liege, Belgium Application March 23;.1'954,.Serial No. 418,128 Claims priority, application France March 25, 1953 15 Claims. (C1 60--57) The present invention relates to pheumatic driving hammers which are particularly suitable for driving in piles, sheet-piling and the like, although it is by no means limited to such applications.

The object of the invention is toprovide a pneumatic hammer enabling a large striking power to be developed notwithstanding that the striking mass is of relatively low weight, in which, moreover, the striking power and the impact velocity are capable of variation over wide limits with the use of simple means. The advantage of this is that the same apparatus may be used for different kinds of operations, requiring very different striking powers, so that a single" apparatus according to the invention is capable of replacing a whole range of theusualtypes of automatic hammers.

For pile driving and similar operations, this is an advantage of some importance since the penetrating force due to the impact may be adapted to the medium which has to be traversed.

The pneumatic hammer according to the invention therefore comprises a striking mass guided with a reciprocating motion in a casing, an air cylinder being formed in one of these elements so as to coact with a piston solidly connected to the other ofthese elements, means being provided for raising the striking mass while compressing the air inside s'aid cylinder and for releasing the mass in question after a given up=stro'ke in order to give rise to the striking motion of said mass under the combined action of its own weight and the expansion of the air compressed in said cylinder, means being provided for regulating the initial pressure of the air inside this cylinder at the commencement of the lifting motion of the striking mass to any value between atmospheric pressure and some arbitrarily determined higher pressure.

The compressed air used for imparting the desired speed of impact to the striking mass is thus able to exert its expansion between two adjustable pressure limits, this making it possible to modify at will the work of expansion and the rate of the residual pressure prevailing in the air cylinder at the end of the expansion and which maintains the striking mass on the object of the impact with a static force of adjustable intensity, enabling an impact of lingering type to be obtained, or, in other Words, this static force opposes the rebounding of the striking mass and holds it in position after each nited States Patent drop until the next lifting motion. This lingering type of impact, hitherto unknown in any of the known systems, provides a very eflective transmission of the kinetic force of the striking mass to the object under the impact.

According to another feature of the invention, the said initial air pressure may be supplied by an air pumpcontaining a cylinder and a piston, one of these members being formed by the striking mass and the other by a member integral with the casing, the cylinder of the pump being connected to the atmosphere through a passage provided with a check valveopening towards the cylinder and to the said air cylinder through a passage 2,787,123 Fatented Apr. l2, 1957 provided with a check valve opening towards the air cylinder, the air cylinder being connected. to the atmosphere by a passage provided with a safety valve opening under the action of a given adjustable pressure, the said pump being of such a construction that its compression ratio is greater than the compression ratio obtained in said air cylinder.-

This safety valve will limit, to a value corresponding to the force necessary for opening valve, the final pressure reached in the air cylinder at the end of the compression stroke, that is, atthe end of the lifting motion of the striking mass, andsince the compression ratio in this cylinder is known, it will likewise determine the final expansion pressure, that is, the initial pressure for the next compression. All that isrequired therefore is to modify the resistance to opening of the safety valve in order to modify the initial pressure and the end compression pressure in the air cylinder or the value of the striking power of the hammer which depends on these pressures. The velocity of the blow of the hammer will be modified at the same time a's i t is dependent on the intensity of the expansion in the air cylinder.

Likewise, in accordance with the invention, the means provided for raising the striking mass and releasing it at the end of the lifting stroke may advantageously consist of a hydraulic motor containing. a cylinder. integral with the casing and a piston to which areciprocating motion is imparted under the action of. the driving liquid, the rod of the piston being connected to the striking mass by a locking mechanism so that the mass in question is carried along by said piston when it rises inside its cylinder under the action of the liquid under pressure supplied under the piston, while at leastone member coac ting with an abutment forming part of: the: cylinder releases the said locking arrangement and. frees the striking mass at the end of the upward travel of. the piston, the rod of this piston being again automatically connected to the :said mass when the locking mechanism engages in it again atthe end of the down travel of the hydraulic piston.

Finally, mechanical means are provided according to the invention for raising the striking mass and releasing it at the end of the tip-stroke.

One embodiment of thepresent invention is described hereinafter with reference to the accompanying drawings, a number of constructional details which are not needed in order to understandthe invention being. left out.

Fig. 1 is a longitudinal sectional View of apneumatic hammer according to the invention taken on the polygonal line 1-1 of Fig; 5, when the striking. mass is at the bottom of its stroke, at the starting momentof the upstroke. x

Fig. 2 represents a similar view taken slightly before the end of the Lip-stroke at the start of the disengagement of the locking means.

Fig. 3 is a similar view with a; locking means disengaged at the end of the upstroke of the mass.

Fig. 4 is a partial similar view slightly before the end of the down-stroke of the hydraulic piston at the start of the engagement of the locking means.

Fig. 5 is a cross-sectional view taken on the line V-V of Fig. 3.

Fig. 6 is a part sectional: view of a: modification, the striking mass approaching the end of its upward stroke.

Fig. 7 is a; complete view, with partsinsection, of the hammer with the control arrangement of the distributor, the hydraulic distributor,- the hingedl y arranged pipe and the pump supplying the hammer with liquid under pressure.

Fig. 8 shows a mechanical system for raisingthe strikmg mass.

As shown more particularly in Figs. 1 to 5, the hammer comprises a casing 1 which is of square cross-section in the example illustrated, provided with a cover 2 and a bottom part 3 acting as the anvil, these three elements being connected together by four tie rods 4 extending between the cover 2 and the bottom 3 at the corners of the casing 1. For reasons of clarity only the top part of the right-hand tie rod has been shown in Fig. 1. Dogs 5 project underneath the bottom part 3 and are used for example for centering the hammer on the head of a pile or the like.

The striking mass which is cylindrical externally is provided with an under frusto-conical shaped part 6 and an upper cylindrical part 7, these two parts being connected together with a mating ridge 8 and screws, not shown, with the heads embedded inside recesses in the base 6. The mass 6, 7 is guided by eight outer guide sleeves 9 embracing the tie rods 4, four of these sleeves being arranged at the top part and four of them at the lower part of the said mass. The latter is provided with a central cylindrical hollow part 10 embracing a piston 11 formed by the enlarged end of a cylinder 12, the whole of the latter unit being secured to the cover 2 by means of tie rods 13.

Twelve radial openings 14 are provided in the lower part of the wall of the cylinder 10. Eleven of these openings open into closed cylindrical cavities 15 formed in the thickness of the member 7 and serving as clearance space. The twelfth opening 14 opens into a passage 16 leading to an air pump cylinder 17 in the body 7 parallel to the cylinder 10. A check valve 18 opens towards the cylinder 10 and is arranged in the passage 16, the latter being able to communicate with the atmosphere through a safety valve 19 loaded by means of an adjustable tension spring. The detail of this valve has not been shown in Figs. 2 to 4. It consists for example of a ball under the action of a pressure spring fitted inside a cup screwing into a fixed recess, the tension of the spring being adjusted by screwing the cup in question in or out. In order to facilitate this operation a port 19' may be provided in the casing 1 opposite the said cup member when the striking mass is in the position illustrated in Fig. 1.

An air pump piston 20, shown half of it in section, and the other half as an outer view, is provided with packing and engages in the cylinder 17 and is fixed to the cover 2 by means of the rod 21. A check valve 22 opening towards the cylinder 17 is provided in the piston 20.

A piston 23 provided with packing and integral with a rod 24 engages the cylinder 12, the top end of which is connected to the distributor 53, Fig. 7, by means of a pipe line 55. The rod 24 is guided in the central opening formed in the piston 11 and provided with packing rings, the diameter of the opening in question being smaller than that of the bore of the cylinder 12. Four radial bores 26 are provided in the body of the piston 11 and are connected to pipes 27 connected with the distributor 53, shown in Fig. 7. The rod 24 is provided at its other end with a cylindrical foot 28 able to engage in a cavity 29 (Fig. 4) of corresponding shape formed in the upper face of the base 6 of the striking mass. The foot 28 is provided with a system for attaching the mass 6, 7 to the rod 24, this system consisting of two catches 30 slidingly mounted inside diametrically opposite horizontal recesses formed inside the foot 28. The ends of these catches 30 are beak-shaped having an upper horizontal face and a lower inclined face, the inclination of which corresponds to that of an opened out part at the upper edge of the cavity 29. Two tension springs push out the catches towards the outside, their projecting position being limited by the abutments 31 (Fig. 1). In each of the catches mentioned there is a mortise 32 provided with an inclined plane. Two push elements 33 projecting from the top face of the foot 28 are slidingly mounted inside vertical recesses formed in the said foot and in the same axis as the mortises 32, these push elements terminating in a bevel part which coincides with the inclined plane of the corresponding mortise. Springs 34 normally maintain the push members in the position. shown in Fig. 1. There is a cavity 35 formed in the lateral wall of the cavity 29 to serve as a catch for the catches 3% when the foot 28 is engaged in this cavity 29.

Holes 36 are provided in the casing 1 so that there will be atmospheric pressure in the casing all round the striking mass 6, 7 above the piston 20.

The whole apparatus can be moved around easily by means of an eye bolt 37 fixed on the cover 2.

The pneumatic hammer described works in the following manner:

On starting, all the members are situated in the position shown in Fig. 1, the striking mass 6, 7 being attached to the foot 28 integral with the rod 24 of the piston 23 by the catches 30 engaging in the cavity 35. The piston 20 of the air pump occupies the position at the end of the up-stroke.

Oil under pressure, supplied by an auxiliary pump 50 shown in Fig. 7, arrives through the pipe line 27 and the bores 26 into the cylinder 12, under the piston 23, causing it to rise taking with it the mass 6, 7. At the commencement of the first up-stroke, the air inside the cylinder 17 of the pump and the air cylinder 10 with its clearance spaces 15 is at atmospheric pressure. The check valve 22 is closed during the up-stroke and the air is compressed in the spaces 10, 15, 17. The respective clearance spaces of the pump cylinder 17 and of the air cylinder 10 being proportioned in such a manner that the compression ratio is much greater in the pump cylinder than in the air cylinder, the pressure increases more rapidly inside the cylinder 17 and opens the check valve 18 so that air is delivered from the cylinder 17 into the cylinder 10 through the passage 16 and the corresponding opening 14.

Towards the end of the up-stroke, shown in Fig. 2, the push elements 33 come against the under face of the piston 11 and descend in the foot 28 of the rod 24, their end bevels coacting with the inclined faces of the mortises 32 and causing the catches 30 to enter their recesses. This retraction of the catches 3t) releases the striking mass 6, 7 which is propelled downwards on to the anvil 3 under the combined action of its own weight and the expansion of the compressed air in the cylinder 10 and the clearance spaces 15.

The check valve 18 closes at the end of the compression. The air in the cylinder 10 and in the clearance spaces 15 expands during the whole of the descent of the striking mass.

Inside the cylinder 17 of the air pump there is first of all an expansion of the air remaining in it and as soon as this air has reached sub-atmospheric pressure the valve 22 opens and lets air in from the outside so that at the end of the down-stroke of the striking mass, the cylinder 17 is again filled with air at atmospheric pressure. 7 After the release of the striking mass, when the piston 2? has reached the top of the up-stroke, the distributor interrupts the supply of liquid under the piston 23 and delivers the liquid under pressure to the top face of the piston through the pipe line 55, shown in Fig. 7. The piston 23 descends under the action of the pressure of the oil and the weight of the moving elements Z3, Z4, 28 and forces the oil through the piping 27. At the bcginning of this down-stroke, the springs 34 move the push elements 33 back into their initial position and free the catches (it) so that they are forced outwards by their springs. Towards the end of the stroke, the catches encounter the inclined edge of the opening 29 as shown in Fig. 4, so that they are forced into their recesses until they find themselves opposite the cavity 35 into which they engage under the action of their springs, so that the mass 6, 7 is attached once more to the piston 23 and the unit is again in the position shown in Fig. 1 ready for another ascent of the striking mass, the oil pressure being in the meantime re-established in the piping 27.

sesame The initial pressure inside the air cylinder is however already greater than atmospheric pressure on accourit of the supplementary quantity of air which has been introduced into it by the pump 17, so that the final compression pressure will be increased as a result. At each cycle, the initial pressure and the final compression pressure inside the cylinder iii and the clearance spaces 15 will be increased until the final pressure has reached the value determined by the regulation of the safety valve.

This normal working pressure is reached after a numher of cycles which is a function of the value of this pressure and from this moment, the pump is only used to compensate losses in order to keep the working pressure at the desired value. The air surplus delivered by the pump will be evacuated by the valve 19. The residual pressure inside the cylinder it? after each expansion exercises a static force on the mass 6, 7 and provides the lingering impact. This pressure may be determined at will and it may be modified according to requirements, by regulating the valve 19. Of course, a set of interchangeable valves 19 might be used each provided with a spring of different strength but it is simpler to use a valve the pressure of which is adjustable than to replace the valve.

It will be noted that the apparatus does not require the use of steam or compressed air to be supplied by a separate generator. This helps to prevent any disturbance in the working which frequently takes place with compressed air apparatus on account of small losses which are practically unavoidable. The hydraulic system de scribed for raising the striking mass may be replaced by any suitable form of actuating arrangement such as for example an electric arrangement or a mechanical arrangement, and example of which will be descibed hereinafter with reference to Fig. 8.

In Fig. 6 is shown another system of attaching the striking mass. In this case, the foot 33 of the rod 24 comprises two diametrically opposite recesses in which are arranged two hooks 39 able to oscillate through the medium of ball or roller hearings on two pivots 49 fixed in the foot and passing through the recesses formed in the latter. Two tension springs 43. situated on either side of the rod 24 are attached to extensions 42 of the hooks above the pivots 4! These springs therefore have a tendency to force the lower beaks of the hooks 39 towards the outside.

in its upper face the mass 6 is provided with a central cavity inside which extend two pins 43 mounted on ball or roller hearings in said mass. Two parts id; each forming an inclined surface 45 above a pin 43 are fixed the two abutments 47, these being provided for cooperating with heels 43 on the hooks 39 and being mounted with shock absorbers consisting for example of a series of Belleville rings 49.

The mass 6, 7 is shown in Fig. 6, attached to the rod 24, at the moment when it is about to be released at about the end of the tip-stroke. The heels 48 of. the hooks come into contact with the abutments- 47 and rock the hooks on the pivots while the rod 24 con tinues its upward motion. The beaks of the hooks roll over the pins 43 and escape from them, at the same time releasing the mass 6, 7 and reassume the position illustrated under the action of the springs 41.

After the descent of the striking mass, the rod 24 redescends, the beaks of the hooks meeting the inclined surfaces and being moved to the inside against the action of the springs 41, then sliding over the pins 43 and hooking finally under them. In this way, the mass 6, 7 is again attached to the rod 24 and follows the latter during its up-motion.

Fig. 7 shows a hydraulic control arrangement for proseeing the reciprocating runner: of the red some head 286d this rod being provided with a device of s'orr're forin for attaching the mass 6, '7. The li uid under pressure is supplied by a pump 50 driven by an electric motor or other driving means. The motor-pump unit isrriounted on an independent chassis or on the platform of the machine to which the hammer is suspended. The pump is connected to the hammer by means of a. double articulated piping Si, 52, this being necessary through the displacement of the hammer as the pile, sheetpile or the like is driven in. These pipes, or the suction and delivery respectively of the pump, are connected to the distributor 53 situated inside a recess surmounting the cover 2 and connected by a pipe 27 to the lower part of the cylinder 12 and with a pipe 55 to the upper part of the same cylinder. The distributor is controlled by a push element 56 sliding inside a sleeve 57 and provided at its lower part with a double abutment 58, 59 arranged inside a central hollow part 60 of the rod 24:

When the liquid under pressure is delivered through pipe 2'7 under the piston 23, the latter rises until the bottom of the hollow part 60 encounters the abutment 59 and displaces the push element 56 controlling the distributor 5;. and interrupting the supply through the pipe 27 and supplying the liquid under pressure through the pipe 55 to the top of the piston 23, the liquid situated under the piston escaping back through the pipe 27. At about the end of the descent of the piston, the upper wall of the hollow part 60' meets the abutment 58 and takes the push element 56 along with it so as to reverse the distributor, the latter then delivering liquid under pressure once more under the piston to produce a new tip-stroke of the rod 24.

As shown in Fig. 8; the rod may also be driven mechanically. The rod 24 is provided with a head 61 provided with shoes sliding inside a guide 62 fixed to the cover 2 of the pneumatic hammer. This head is connected to a connecting rod 63 passing freely through this cover and provided with a to and fro motion by a mechanism inside a casing fixed to the cover 2. In the example, this mechanism comprises a motor 64, of electr'ical or another type, which actuates through a set of bevel gears 65 and some form of reduction gear 66 a crankshaft 67 to the pin of which is connected the end of the rod 63.

I claim:

1. A pneumatic driving hammer, particularly suitable for driving piles, sheet-piling and the like, comprising. a casing; open to the atmosphere, the base of said casing forming an anvil, a striking mass guided with a reciproeating motion therein, anair cylinder and piston assembly, a portion of said air cylinder and piston assembly being formed by said striking mass, another portion of said air cylinder and piston assembly being connected to said casing, first means for raising the striking mass and thereby compressing air contained in said air cylinder, said first means freeing said striking mass after a given raising of said striking mass so as to produce a striking motion of said striking mass under the combined action of the weight of said striking mass and the expansion of the air compressed inside said air cylinder, and second means for establishing an initial pressure of air above atmospheric pressure inside said air cylinder at the start of the upward movement of the striking mass;

2. A pneumatic hammer as claimed in claim 1, including a pneumatic pump for producing the initial pressure and having a compression ratio greater than that in said air cylinder, said pump consisting of a pump cylinder and pump piston assembly, a portion of said pump cylinder and pump piston assembly being formed by the striking mass, another portion of said pump cylinder and pump piston assembly being formed integral with said casing, a passage connecting said pump cylinder with the atmosphere, a check valve arranged in said passage and opening towards said pump cylinder, a second passage connecting the pump cylinder with said air cylinder, at check valve arranged in said second passage and opening towards said air cylinder, and a safety valve connecting said air cylinder with the atmosphere and having a resistance to opening corresponding to the maximum pressure to be reached in said air ,cylinder.

3. A pneumatic hammer as claimed in claim 2, in which means are provided for adjusting the resistance to opening of said safety valve.

4. A pneumatic hammer as claimed in claim 1 in which said air cylinder permanently communicates with a clearance space formed outside said air cylinder.

5. A pneumatic hammer particularly suitable for driving piles, sheet-piles and the like comprising a casing, a prismatic shell thereof, a bottom forming an anvil and a cover connected to said bottom by means of longitudinal tie rods, a striking mass mounted for reciprocating motion in said casing, an air cylinder formed by a hollow central part of said striking mass, a pump cylinder formed from the upper face in said mass at the side of said hollow central part, a passage connecting the bottom ends of said pump and air cylinders, a check valve arranged in said passage and opening towards said air cylinder, closed cavities formed in said mass around said air cylinder and communicating with the bottom end of said air cylinder, a piston integral with said cover and engaging in said air cylinder, a piston integral with the cover and engaging with said pump cylinder, a check valve in said latter piston opening towards said pump cylinder, a safety valve connected with the passage joining said cylinders and opening to the atmosphere, guide means for the striking mass in said casing, openings provided in the latter and opening to the atmosphere, and means for raising the striking mass and for freeing said mass after a given up-stroke.

6. A pneumatic hammer as claimed in claim 5, in which said guide means include members integral with said striking mass and slidingly mounted on said tie rods.

7. A pneumatic hammer as claimed in claim 1, in which the means for raising the striking mass and freeing it at the end of the up-stroke comprise a rod slidingly mounted in the hollow central part of the pneumatic hammer and passing in sealed and guided manner upwardly out of the air cylinder, a motor provided for acting on the upper end of said rod and imparting to it a to and fro motion, the rod being also provided with an enlarged foot formed at the lower end of said rod and provided with an automatic attachment mechanism for connecting the rod to said striking mass at the end of the down movement imparted to said rod by said motor, and at least one member supported by the rod for coacting with an abutment integral with the casing for releasing said attachment mechanism at the end the up-stroke of the said rod.

8. A pneumatic hammer as claimed in claim 7, in which the motor acting on the upper end of the said rod is a hydraulic motor, including a cylinder formed by a hollow central part of the piston of the air cylinder, and an enlarged head being formed on said rod for forming the piston of the hydraulic motor.

9. A pneumatic hammer as claimed in claim 8, including means for alternately introducing driving liquid to the bottom and top faces of the hydraulic piston, and for simultaneously evacuating the liquid from above, respectively below said piston.

10. A pneumatic hammer as claimed in claim 8, including pipes for passing liquid which open into the bot tom end and into the top end of the hydraulic cylinder respectively, a distributor mounted on the pneumatic hammer and connecting these pipes to the suction and delivery pipelines respectively of a hydraulic pump and means for actuating this distributor and thereby changing the connections between these pipes and pipe lines at the end of each stroke of the hydraulic piston.

11. A pneumatic hammer as claimed in claim 10, in which the means for actuating the distributor include a push element traversing the hydraulic cylinder and having its lower end penetrating into a central cavity formed in said rod, and two abutments provided on said push element for coacting with the upper wall and with the bottom wall of the said central cavity respectively.

12. A pneumatic hammer as claimed in claim 7, in which the upper end of the said rod is guided axially inside a hollow part of the pneumatic piston and open to atmosphere, the motor acting on said upper end including a connecting-rod connected to said upper end and passing freely upwards out of said hollow part, the connecting rod being also connected to a mechanical drive system mounted on the hammer and imparting a to-andfro motion to the connecting-rod.

13. A pneumatic hammer as claimed in claim 7, including a central cavity formed in the bottom of the air cylinder for receiving the enlarged foot, horizontal recesses formed in the enlarged foot, catch elements with beak-shaped outer ends slidably mounted in said recesses, springs acting on said elements for forcing them towards the outside so that the beak-shaped ends project laterally, a recess provided in the lateral wall of said cavity for receiving said beak-shaped ends to attach the said rod to the striking mass, push elements provided with beveled lower ends mounted vertically in sliding manner in said foot, a mortise having an inclined inner lateral face in each of said catches opposite one of said push elements, so that when the push elements, abutting against the pneumatic piston at the end of the up-stroke, are forced into said foot against spring action, they push the said catches into their recesses and so release the foot from the said striking mass.

14. A pneumatic hammer as claimed in claim 7, including two hooks mounted in rocking manner on pivots carried by the said foot pins supported by the striking mass for coacting with said hooks, springs acting on the hooks for displacing them in a direction corresponding to their attachment to the pins of the striking mass, upper extensions provided on these hooks, abutments provided on the bottom face of the piston of the air cylinder for coacting with said extensions at the end of the upstroke of said rod and thereby displacing the hooks against the action of said springs.

15. A pneumatic hammer as claimed in claim 14, in which the said abutments are resilient.

References Cited in the file of this patent UNITED STATES PATENTS 858,322 Bandimere June 25, 1907 1,320,688 Healy Nov. 4, 1919 1,380,072 Miller May 31, 1921

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