US2906245A

US2906245A - Steam actuated hammers

Info

Publication number: US2906245A
Application number: US678181A
Authority: US
Inventors: Harold M Mccall
Original assignee: Raymond International Inc
Current assignee: Raymond International Inc
Priority date: 1957-08-14
Filing date: 1957-08-14
Publication date: 1959-09-29
Anticipated expiration: 1976-09-29

Description

sept. 29,` 1959 Filed Aug. l14, 1957 H. M. McALL 2,906,245

STEAM ACTUATED HAmAERs 3 Sheets-Sheet 1` wu iw suiii 41 Sept. 29, 1959 H. M. MccALl. 2,906,245

STEAM ACTUATED HAMMERS Filed Aug. 14, 1957 'l 3 Sheets-Sheet 2 1N VENTOR. 520k Hq/POLDMCALL.

A TTORNEK.

sept. 29, 1959 2,906,245'

H. M. McCALL STEAM ACTUATED HAM/:ERS

Filed Aug. 14, 1957 3 Sheets-Sheet 3 ArroR/VEKS.

United States Patent STEAM ACTUATED HAMMERS Harold M. McCall, Fairlawn, NJ., assignor to Raymond International Inc., New York, N.Y., a corporation of New Jersey Application August 14,1957, Serial No. 678,*181

5 Claims. (Cl. 121-30) This invention relates to improvements in doubleacting, differential piston-type power hammers of the kind having Widespread utility in the installation of piles and the like and, more particularly to such type hammers having a unique and novel main control valve actuated by an auxiliary differential piston and cylinder assembly.

An improved form of double acting, dilferential pistontype hammer is disclosed in U.S. Patent No. 2,598,455, issued May 27, 1952, to Edward A. Smith. Hammers 0f this type have received and are enjoying Wide acceptance and utility in the pile driving eld. In the driving of piles it is most important that the actuating hammer deliver a precisely predetermined amount of energy per blow to the pile. This is essential because the bearing capacity of most piles is determined by measuring the inches of penetra-tion of the pile per hammer blow for the last few blows of a driving operation. Many formulas are available for calculating the pile bearing capacity from the amount-of energy delivered by the hammer and the amount of penetration per blow. Since the energy per hammer blow will for any given differential piston-type hammer, having a ram of fixed weight and a stroke of fixed length, vary in accordance with the steam pressures in the differential assembly, it is most import-ant to insure that such steam pressures are of a precisely known quantity, for otherwise calculation of the pile bearing capacity pursuant to the above formulae will be subjected to serious error. Quite obviously, since a piles bearing capacity determines the adequacy of the supported structures foundation, any error in the determination of this bearing capacity may later result in the settling or sinking of this structure and, therefore, would be most serious.

As described in column 4 of said Smith Patent No. 2,598,455, the energy delivered by a hammer of this type depends largely on the difference between the downward force created by the steam above the larger piston of the differential assembly and the upward force created by the steam in the space between the two pistons. When, as described in that patent, the steam pressure is the same in the space between the pistons and the space above the larger piston, that part of the area of the large piston which corresponds in size to the area of the small piston will be effective in contributing force to the downstroke of the assembly. Since this area of the smaller piston is fixed by the design of the hammer, as long as the steam pressures above and below the larger piston are the same, the hammer will deliver its predetermined rated energy per blow. However, should there be any variation in the steam pressures above and below this larger piston, this will result in variations in the energy delivered per hammer blow. In the aforesaid Smith patent disclosure, the entry of steam to the upper side of the larger piston is mechanically controlled by means of a reciprocating rod and a lever, which serve to actuate main steam valve 38. Experience with this type of hammer has shown that if the steam pressure introj 2,906,245 Patented Sept. 29, 1959 ice duced to the space between the two pistons of the assembly is only very slightly below its rated value, the larger fpiston tends to rise with less than normal velocity, and in some instances may not fully throw the valve lever, which results in the steam entry passage to the space above the upper piston being not completely opened. Therefore, the steam entering into this space above the upper piston will be throttled in passing through the only partially open valve. Since, however, the steam entering into the space between the pistons is never throttled because that space is connected directly and permanently to the main steam line and does not at any time depend upon a valve opening, any such throttling of the steam into the space above the large piston will result in a variation in pressure above and below that piston and this will result in a disproportionately large variation in the effective downforce on the ram, thereby seriously reducing the energy per blow of the hammer.

The present invention relates to hammers of the type disclosed in said Smith Patent but having a simple, durable and unique main control valve assembly which eliminates the above-described tendency toward variations in the energy per blow of the hammer assembly. According to the present invention, the main control valve is provided -with an auxiliary differential piston* type actuating mechanism which will always insure that said main steam control valve will open fully and thus provide a hammer blow of precisely uniform energy. Moreover, the valve assembly of the invention is most durable due to its lack of multiple moving parts, and the fact that the only parts of it which `are subject to wear and tear are the piston rings which of course will last for many years. Likewise the mechanism of the invention involves no expensive parts such as special cam rods and the like, and therefore constitutes a considerable saving in the total cost of the hammer assembly.

Other and more specilic objects, features and advantages of the invention will appear from the detailed description given below taken in connection with the accompanying drawings which form a part o-f this specication and illustrate by way of example the presently preferred embodiment of the invention.

In the drawings:

Fig. l is a vertical sectional View, showing a power hammer according to the invention installed in position in the upper end of a pile core;

Fig. 2 is a fragmentary sectional view taken on the line 2 2 of Fig. l and showing portions of the steam passages leading to the auxiliary differential piston assembly;

Fig. 3 is a fragmentary vertical sectional view taken approximately on the line 3-3 of Fig. 2 but showing the main differential piston assembly of the hammer at its lposition at the start of an upstroke;

Fig. 4 is a fragmentary vertical sectional View taken approximately on the line 4-4 of Fig. 2 but showing the main differential piston assembly approximately midway through its upstroke;`

Fig. 5 is an enlarged fragmentary vertical sectional view taken on the line 5 5 of Fig. l and showing the main steam control valve and its auxiliary differential piston actuating mechanism;

Fig. 6 is an enlarged fragmentary sectional view of the main control valve and actuating mechanism showing the parts in their relative positions when the main control valve is open, thereby connecting the space above the larger piston of the main dilferential piston assembly to the steam supply;

Fig. 7 is a View Similar to Fig. 6 but showing the same parts in their relative positions when the main control valve is closed, thereby connecting the space above the large piston of the main diiferential to exhaust; and

Fig. 8 is a fragmentary sectional view taken on the line 8-8 of Fig. 6.

Referring now to the drawings and particularly to Fig. l thereof, it will be noted that the hammer assembly of the invention may in many respects be similar in design to the hammer disclosed in the aforesaid E. A. Smith Patent No. 2,598,455, and it should be understood that except as hereinafter specifically set forth the construction and mode of operation of the instant hammer assembly may correspond to that of said patent. As shown, the hammer assembly comprises a hammer body or cylinder assembly 20 which includes an upper cylinder 21 of relatively large diameter and a lower cylinder 22 of smaller diameter with

pistons

23 and 24 of corresponding sizes being respectively positioned in said cylinders. These pistons are integral with or rigidly mounted upon a single piston rod 25 having a lower portion 26 tted within the upper end of a ram 27. As pointed out in the aforesaid Smith patent, the lower, smaller cylinder of the hammer body and the ram are adapted to be received within the working portion 28 of a core which is of normal diameter. The invention is, however, of course applicable to hammers adapted for use with other driven elements or other types of cores. Again as described in the aforesaid Smith patent, the space between

pistons

23 and 24 of this main differential piston assembly is constantly connected via ports 30, passages 30a and chamber 30h directly to the steam supply line 31, whereas the steam under pressure is delivered to the space above the large upper piston 23 only during the greater part of the downstroke and momentarily during the final part of the upstroke to cushion the final upward movement of the hammer. A main steam control valve 32 may be mounted on the top of the hammer and is provided with three ports, namely, exhaust port 34, steam inlet port 35 which is connected to the steam inlet chamber 30b, and port 36 which is connected via passage 36a, chamber 37 and conduits 38 to the space above the larger piston 23 of the main differential piston assembly. The control valve 32 may comprise a rotatable member 33 having grooves formed on its sides which are adapted, respectively, when the valve is open to connect

valve ports

35 and 36, thereby connecting the space above piston 23 with the steam inlet, when the valve is closed to connect

valve ports

34 and 36, thereby venting the space above piston 23 to exhaust.

As shown in Figs. -7, an auxiliary steam operated differential piston assembly is provided to control the positioning of the valve member 33. This assembly comprises a relatively large cylinder 41 and a smaller cylinder 42 in which there is disposed a rigid piston assembly 43 having

pistons

44 and 45 corresponding, respectively, in size to the

cylinders

41, 42. The piston assembly 43 is connected by means of a connecting rod 46 and a lever 47 to a rotatable shaft 48 in the steam control valve 32 on which is mounted the valve member 33. This auxiliary differential piston assembly is connected by steam passages as follows to the main differential piston assembly of the hammer. As best seen in Fig. 5, the space 50 between piston 44 and the head of cylinder 41 (i.e., the space right 0f piston 44) is in constant communication via passage 50a, 501;, 50c, 50d and 50e with` a port 51 provided in the side wall of the smaller cylinder 22 of the main dilferential assembly. The space 52 between auxiliary pistons 44 and 45 (i.e., to the left of piston 44) is, on the other hand, in continuous communication via

passage

52a, 52h, 52e` and 52d with a port 53 formed in the side wall of the larger cylinder 21 of the main differential assembly.

The operation of the hammer assembly and its control valve is as follows. When the hammer starts to operate, the ram is all the way down with the main

differential pistons

23, 24 being in the lower portions of their respective cylinders as shown in Fig. 3. As there shown, steam under pressure is being delivered through passages 30a and ports 30 to the space between

main pistons

23 and 24. In this position as shown, small piston 24 is below port 51, and thus steam under pressure is passing from the space between the

pistons

23, 24 through port 51 and

passage

50e, 50d, 50c, 5017 and 50a to the space 50 on the right of the larger piston 44 in the auxiliary differential piston assembly. When this steam pressure has built up sufficiently in space 50, the auxiliary differential piston assembly 43 will be forced to the left, thereby throwing valve member 33 to the closed or exhaust position (as shown in Fig. 7), with port 36, leading from the space above main piston 23, being connected to the exhaust port 34. With the ports in this position, continued entry of steam under pressure through the passages 30a and ports 30 will cause the main

differential piston assembly

23, 24 to rise, thereby lifting the ram. As the ram is lifted, piston 24 in due course passes port 51 as shown in Fig. l, thereby permitting the escape of all steam from the space S0 through passage 50a to 50e and out through port 51 to exhaust. As the ram continues to move upward, it gains momentum, and main piston 23 in due course passes port 53, thereby admitting steam under pressure from the space between the pistons of the hammer assembly through port 53 and

passage

52d, 52C, 52b and 52a to the space 52 between

pistons

44 and 45 in the auxiliary differential piston assembly. This entering steam will force the auxiliary differential piston assembly 43 to the right to the position shown in Fig. 6, thereby shifting valve member 33 clockwise to its open position with port 36, leading from the space above piston 23, being connected to the steam supply port 35. Thus as the ram approaches the top of its stroke, steam under pressure is admitted into the space above main piston 23, thereby serving to cushion the upper end of the stroke. With the steam pressure on both sides of main piston 23 now being equal, in accordance with the well known principle of differential piston assemblies, a greater force is being exerted on the upper face of piston 23 and, therefore, the ram will be forced down by the differential steam action, as well as by gravity. As its downward travel continues, piston 23 will pass port 53, but this does not shut otf the steam connection to space 52 because it takes only a negligible fraction of a second for the piston 23 to pass completely over the port 53, thereby connecting that port with the space above piston 23, which space at this particular portion of the cycle is under the same steam pressure as the space between

pistons

23 and 24. This continued maintenance of pressure to the space between

auxiliary pistons

44 and 45 insures that the main valve 32 will remain fully open until such time as it is thrown to the exhaust or closed position. Still further downward travel of the main differential piston assembly of the hammer causes piston 24 to pass port 51, thereby again admitting steam through port 51 and passage 59e to 50a to the space 50 on the right of piston 44- of the auxiliary differential piston assembly. Although there is still the same steam pressure to the left of this piston 44, in accordance with the differential piston principle as described above, the force acting to urge piston 44 to the left will be greater and, therefore, the valve member 33 will again be thrown to exhaust as shown in Fig. 7. With the parts in this position, steam will not only exhaust from the top of cylinder 21 but also will exhaust from the space 52 via passage 52a-52d and port 53. Once the steam has been exhausted from the space above piston 23, the incoming steam to the space between

pistons

23, 24 will once again cause the piston assembly and ram to rise, and this time piston 24 will again pass over the port 51 and allow the steam in space 50 to exhaust, but this does not result in any change of position of valve member 33 because the steam in space 52 has already been exhausted. The ram, therefore, continues upwardly, and the complete cycle is repeated time and time again.

Although a certain particular embodiment of the invention is herein disclosed for purposes of explanation, various other modications thereof, after study of this specification, will be apparent to those skilled in the art to which the invention pertains. Reference should accordingly be had to the appended claims in determining the scope of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A double-acting, dilerential piston-type fluid pressure operated hammer having interconnected upper and lower main pistons, contained respectively in relatively large and smaller cylinders, valve means and connections for maintaining substantially a constant pressure between said main pistons and for maintaining pressure above the larger main piston during the greater part of its downstroke and the nal part of its upstroke for cushioning purposes, and an automatic actuating mechanism for said valve means comprising an auxiliary diierential piston assembly connected to said valve means and having interconnected relatively large and small auxiliary pistons, the space between said auxiliary pistons being connected to receive operating fluid pressure from the space between the main pistons during the iinal part of the up stroke of the main pistons, thereby opening the valve means to admit operating pressure above the larger main piston, and the space between the larger auxilitry piston and the head of its cylinder being connected to receive operating fluid pressure from the space between said main pistons at a time near the end of the downstroke of the main pistons for restoring said valve means to closed position.

2. A double-acting, differential piston-type uid pressure operated hammer having interconnected upper and lower main pistons, contained respectively in relatively larger and smaller cylinders, valve means and connections for maintaining substantially a constant pressure between said main pistons and for maintaining pressure above the larger main piston during the greater part of its downstroke and the iinal part of its upstroke for cushioning purposes, and automatic valve actuating means comprising an auxiliary differential piston assembly engaging said valve means and having interconnected relatively large and small auxiliary pistons with passage means connecting the space between said auxiliary pistons to the larger main cylinder and passage means connecting the space between the larger auxiliary piston and the head of its cylinder to the smaller main cylinder so as to provide for passage of operating fluid pressure to open and close said valve means automatically.

3. A double-acting, differential piston-type iluid pressure operated hammer having interconnected upper and lower main pistons, means for maintaining substantially a constant pressure in the space between said main pistons, valve means for selectively controlling the pressure above the larger main piston and automatic valve actuation means comprising an auxiliary differential piston assembly positioned so as to actuate said valve means and having connections for receiving operating fluid pressure from the space between the main pistons to open the valve means during the final part of the upstroke of the main pistons and to close the valve at a time near the end of the downstroke of the main pistons.

4. In la double-acting, differential piston-type fluid pressure operated hammer having interconnected upper and lower main pistons, a main control valve and passages for maintaining substantially a constant pressure between said main pistons and for maintaining the same pressure above the larger main piston during the greater part of its downstroke and the nal part of its upstroke for cushioning purposes, the improvement which comprises an automatic valve actuation means comprising an auxiliary differential piston assembly connected to said valve means and having interconnected relatively large and small auxiliary pistons, passage means extending from the space between said auxiliary pistons to receive operating fluid pressure from the space between the main pistons during the nal part of the upstroke of the main pistons, and passage means extending from the space between the larger auxiliary piston and the head of its cylinder to receive operating fluid pressure from the space between said main pistons at la time near the end of the downstroke of the main pistons, said auxiliary differential assembly being adapted to open and close said valve means in response to the entry of fluid pressure from said passages, respectively.

5. A double-acting, fluid pressure operated hammer having interconnected upper and lower main pistons, valve means and connections for maintaining substantially a constant pressure between said main pistons and automatic valve actuating means comprising an auxiliary dilerential piston assembly linked to said valve means and having interconnected relatively large and small auxiliary pistons, the space between said auxiliary pistons being connected to receive operating fluid pressure from the space between the main pistons during the nal part of the upstroke of the main pistons, thereby opening the valve means to admit operating p-ressure above the larger main piston, and the space between the larger auxiliary piston and the head of its cylinder being connected to receive operating uid pressure from the space between said main pistons at a time near the end of the downstroke of the main pistons for restoring said valve means to closed position.

References Cited in the tile of this patent UNITED STATES PATENTS 1,595,939 Hukill et al Aug. 10, 1926 2,598,455 Smith May 27, 1952 2,789,540 Kapka et Ial Apr. 23, 1957 2,791,097 Smith May 7, 1957