Abstract:
Disclosed is a device for automatically and continuously lifting and dropping a drop hammer. The device has hydraulic and mechanical components which lift and drop the hammer and electromechanical components which sequence various actions and ensure that the hammer is always dropped from a preset height above its last dropped position. This is useful for soil testing in accordance with America Society for Testing and Materials Test D 1586 &#34;Standard Method for Penetration Test and Split Barrel Sampling of Soils&#34; and other tests.

Description:
FIELD OF THE INVENTION 
     This invention relates to hydraulic lifting equipment and electromechanical controls. 
     BACKGROUND OF THE INVENTION 
     The American Society for Testing and Materials publishes standard tests for many materials. One such test, Standard Method for Penetration Test and Split Barrel Sampling of Soils ASTM No. D-1586-84,describes the standard procedure for driving a split barrel sampler into the ground to obtain a representative soil sample and a measure of the resistance of the soil to penetration. This test is known in the industry as the &#34;Standard Penetration Test&#34; and is used extensively in a great variety of geo-technical exploration projects and ecology surveys. ASTM No. D-1586-84 p. 2. In this test, a 140 pound (63.5 kg) hammer is dropped on a split barrel sampler from a height of 30 inches (76 cm) above the barrel to force the barrel into the ground. The barrel, having been forced into the ground, picks out a plug of soil which is removed and analyzed in a laboratory. 
     While driving the barrel into the ground, the operator keeps track of the number of hammer blows needed to drive the barrel one foot (30 cm) into the ground. The number of blows per foot (30 cm) of penetration is called the N count or blowcount. Many widely published correlations relate this blowcount to the engineering behavior of soil and foundations. ASTM No. D-1586-84 p. 2.An accurate blowcount is essential to valid test results. The hammer must be dropped from 30 inches (76 cm) above the barrel before every blow to get an accurate blowcount. Although ASTM No. D-1586-84 allows the use of an automatic drop hammer system, a simple cathead is usually used. An operator simply winds the hammer line up on the cathead until it has lifted the hammer about 30 inches (76 cm). Carelessness and impatience introduce large error into the lift of the hammer. Therefore, blowcounts are likely to be very inaccurate. ASTM No. D-1586-84 does not describe any automatic drop hammer systems. 
     SUMMARY OF THE INVENTION 
     It is the principal object of this invention to provide a device which will automatically and repeatedly lift and drop a drop hammer from a height of 30 inches (76 cm) above its last drop point. It is also an object of this invention to provide a means for manual operation of a hydraulic winch, for raising and lowering the hammer before and after automatic operation. 
     These and other useful objects are achieved by attaching the drop hammer to a line which is run through a pair of pulley blocks and attached finally to a winch. One pulley block is fixed in position and the other is attached to a hydraulic cylinder actuating rod. The winch is used to take up any slack in the line, then is locked. The hydraulic cylinder then lifts the moving pulley block, thus lifting the hammer. When hydraulic power to the cylinder and winch is reversed, the actuating rod is quickly retracted and the hammer falls unimpeded. The cylinder and winch are powered by hydraulic oil and are controlled by solenoid valves. The solenoid valves are controlled by relays, pressure switches and limit switches. The lift of the hammer is controlled by a limit switch activated by the actuating rod. The accuracy of the lift is ensured because the winch takes up the slack in the line before the lifting stroke. An unimpeded hammer fall is ensured by driving the actuating rod down and forcefully turning the winch to provide plenty of slack in the line. 
     This device is useful for ASTM No. D 1586-84 and other materials and soils tests which would benefit from the advantages offered by the device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the apparatus. 
     FIG. 2 is a diagram of the mechanical system. 
     FIG. 3 is a schematic of the hydraulic system. 
     FIG. 4 is a schematic of the electric relay used. 
     FIG. 5 is a schematic of the electric relay control system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, FIG. 1 is a perspective view of the apparatus system. A drop hammer 1 is attached to a line 2 and lowered into a bore hole 3. The hammer line 2 runs up the bore hole, around pulleys 4 and 5, threads twice through a fixed double sheaved pulley block 6 and a moving double sheaved pulley block 7 and finally to a hydraulic winch 8 through a guide pulley 9. The winch 8 has a forward port 10 and a reverse port 11. The moving pulley block 7 is attached to the actuating rod 12 of a hydraulic cylinder 13. The winch 8 is actuated to wind up any loose line 2. Hydraulic oil to the winch 8 is cut off when the line 2 is tight as indicated when pressure switch PS1 senses high pressure in the forward port 10. The winch 8 is hydraulically isolated and thus hydraulically locked. Now hydraulic oil is supplied to the piston bottom chamber 14, thus raising the piston 15. This force acts through the actuating rod 12 to lift the moving pulley block 7. The winch 8 may be replaced, if desired, by a cylinder which is a hydraulic equivalent in this application. 
     A limit switch LS1 is installed so that it is activated when the actuating rod 12 has moved upward 7.5 inches (19 cm). This 7.5 inches (19 cm) travel of the actuating rod 12 lifts the hammer 1 30 inches (76 cm) because the double sheaved pulley block setup creates a 4 to 1 ratio of the block movement to hammer movement. The limit switch LS1 may be moved up or down to adjust the stroke of the hammer 1, and a different number of sheaves in each block may be used to alter the pulley ratio. Also, additional pulley block; pairs and lifting cylinders may be placed on the line to provide increased lifting power. 
     When the limit switch LS1 is hit by the actuating rod 12, hydraulic oil flow to cylinder 13 is reversed so that hydraulic oil is now supplied to the top chamber 16 to exert force on the piston 14. At the same time, the winch 8 is unlocked and hydraulic oil is supplied to the reverse port 9 of the winch 8 and the winch 8 unwinds to slacken out the line 2. The hydraulic cylinder 13 and winch 8 are operated fast enough that the fall of the hammer 1 is not impeded. Hydraulic oil forced from the piston bottom chamber 14 may be used to power the winch 8 in reverse. When the piston 15 has been forced all the way down, pressure builds up on the piston top chamber 16. This is sensed by pressure switch PS2. When pressure switch PS2 senses high pressure, it resets the system and reinitiates the entire sequence. 
     FIG. 2 is a simplified diagram of the mechanical system. The drop hammer 1 is attached to the line 2. The line 2 is fed through a pulley 4, the fixed pulley block 6 and the moving pulley block 7 and finally to the winch 8. The moving pulley block 6 is attached to the actuating rod 12 of the cylinder 13. The winch 8 is used to tighten the line 2 until it is taught. When the line 2 is taught the cylinder 13 is used to lift the moving pulley block 7, thus lifting the hammer 1. When the hammer 1 is lifted the appropriate height the cylinder actuating rod 12 is retracted and the winch 8 is quickly rotated to provide extra slack in the line 2. This allows the hammer 1 to fall unimpeded. When the hammer falls, it drives the split barrel sampler 36 deeper into the bore hole 3, thus coming to rest below the initial position. This is the dropped position. The hammer 1 must be lifted 30 inches (76 cm) from this dropped position and dropped again. A thirty inch (76 cm) lift is ensured because the winch 8 takes up all slack in the line 2 before every lift. 
     FIG. 3 is schematic of the hydraulic system. In understanding the hydraulic schematic, it is helpful to divide the machine operation into four distinct acts: 
     1. Taking up slack in the line. 
     2. Lifting the hammer. 
     3. Dropping the hammer. 
     4. Resetting the system for the next cycle. 
     The system is supplied by any available hydraulic power source 17 through solenoid operated four-way valve 18 which also acts to relieve operating hydraulic oil back to the reservoir of the power source. 
     Taking up slack: in the line solenoid A1 is energized and the four-way valve 18 is open straight. Solenoid C1 to open the winch forward supply valve C2. The winch return port 11, which is also the reverse supply port relieves through the forward winch return valve F2. Solenoid Fl is energized to open the forward winch return valve F2 which allows operating oil from the winch 8 to relieve the reservoir 19 through the four-way valve 18. When the line 2 gets tight, the pressure builds up in the forward winch supply line 20. This is sensed by pressure switch PS1 which then de-energizes solenoid C1 and solenoid F1, shutting valve C2 and valve F2 and hydraulically locking the winch 8. 
     Lifting the hammer: High pressure on pressure switch PS1 also causes solenoid Dl to energize, thereby opening the cylinder bottom supply/return valve D2. Four-way valve 18 is still open straight, so hydraulic oil is supplied, through valve D2 to the piston bottom chamber 14 thereby forcing the piston 14 and actuating rod 12 upward. The piston 14 and actuating rod 12 move upward until the limit switch LS1 is met. 
     Dropping the hammer: Contact between the limit switch LS1 and the actuating rod 12 causes solenoid A1 to de-energize and solenoid D1 to de-energize. It also causes solenoids B1, D1, E1, and C1 to energize. In this state, the four-way valve 18 is open/crossed to supply hydraulic oil to the top chamber 16 of the piston 14. Cylinder bottom supply/return valve D2 is open to relieve oil from the piston bottom chamber 14. Reverse winch supply valve E 31 is open to divert some piston bottom oil to the winch reverse port 23. Forward winch supply valve C2 is open and acts as the return valve for reverse winch operation. The piston 14 and actuating rod 12 are forced downward and the winch 8 is unwound. This relieves all tension on the line 2 and the hammer 1 falls. 
     Resetting the system: Pressure switch PS2 on the piston drive down supply line 21 senses pressure in the top chamber 16 of the cylinder 13 when the piston 14 has been driven all the way down. This condition indicates that the hammer 1 has fallen. Pressure switch PS2 operates to de-energize solenoids B1, D1, E1 and C1 and to energize solenoids A1, C1, and F1. This is the initial state of the system, and the cycle now repeats. 
     Included in the system are two bidirectional flow control valves. The winch flow control valve 22 throttles hydraulic oil flow for forward winch operation, which must be slowed to avoid lifting the hammer during any delayed response time of the pressure switch PS1, but allows unrestricted return flow from the winch forward port 10 during reverse winch operation. Cylinder flow control valve 23 throttles hydraulic oil flow to the cylinder bottom chamber 14 during the dropping action in order to force some return oil through the winch 8 during the dropping action, but allows unrestricted flow of hydraulic oil to the cylinder bottom chamber 14 during the lifting stroke. 
     FIG. 4 shows the electrical schematic for the control relays. All relays are wired the same, as follows: 
     Pole P8 is always energized from the power source and is connected to the solenoid power contact. 
     Pole P6 is connected to the corresponding solenoid valve. Power is supplied to pole P6, and hence to the corresponding solenoid valve, when the solenoid power contact 35 is lifted and latched. A latching coil 36 is connected between pole P2, and pole P7. Pole P7 is grounded. Pole P2 is to energize the latching coil 36 and energized to lift both the solenoid power contact 35 and the coil latching contact 26. 
     Pole P1 is connected to the coil latching contact 26, and is energized whenever Pole P2 is energized. 
     Pole P3 is energized through one of the control switches. 
     Poles P4 and P5 are not used. Each relay works in the same manner as follows: 
     When pole P3 is energized through the applicable control switch and voltage is momentarily applied to poles P1 and P2 the latching contact 26 is lifted into contact with pole P3. With voltage no longer applied to poles P1 and P2, voltage is supplied through pole P3 and the latching contact 26 to pole Pl, then to pole P2 and through the latching coil 36, through pole P7 to ground. Pole P3 thus acts as a latching power source. Power is supplied to the corresponding solenoid valve because the solenoid power contact 35 is always lifted in tandem with the latching contact 26, and completes the circuit between the power source, pole P8, pole P6 and the solenoid. Power to the solenoid is secured when the control switch opens and pole P3 is de-energized, thus de-energizing the latching coil 36, thus dropping both the latching contact 26 and the solenoid power contact 35. This breaks the circuit between pole P8 and pole P6, thus de-energizing the solenoid connected to pole P6. FIG. 5 shows the control circuit. Overall circuit operation is as follows: 
     Taking up slack: The spring loaded start switch 27 is depressed and momentarily energizes poles P1 and P2 on relays A3, C3, F3. This lifts the latching contact and power contact of each relay. Solenoids A3, C3, and F3 are thereby energized and valves A2, C2 and F2 of FIG. 2 are opened to start the winch tightening step. When the winch 8 is tight and forward winch supply line pressure increases, pressure switch PS1 breaks contact with the low pressure contact 28 and makes contact with the high pressure contact 29. Because the low pressure contact 28 of pressure switch PS1 is the only power source for latching pole P3 in relays C3 and F3, the latching contacts and power contact drop and the latching coil is de-energized and solenoid C1 and solenoid Fl are de-energized. Thus valve C2 and F2 are shut and the winch is hydraulically latched. 
     Lifting the hammer: The lifting sequence begins because the high pressure contact 29 of pressure switch PS1 energizes the pick up pole P2 of relay of D1. This picks up the latching contact, and contacts latching pole P3, thereby latching both the latching contact and power contact of relay D1. Thus solenoid D1 is energized and piston bottom supply/return valve D2 is open and hydraulic oil is supplied to the piston bottom chamber 14 and the piston 15 is raised. Thus, the piston 15 and actuating rod 12 move upward until reaching and contacting the limit switch LS1. 
     Dropping the hammer: When the actuating rod hits limit switch LS1, it switches to the drop contact 30. This de-energizes pole P3 of relay D1. Also, the latching pole P3 of relay A3 is de-energized and solenoid A1 is de-energized. Contact with the drop contact 30 of LS1 supplies voltage to the pick up poles pole P2 of relays B3, D3, F3 and C3, lifting the latching contact and power contact of each relay. Latching power is supplied to relay B3, D3 and E3 through pressure switch PS2. Relay C3 energizes solenoid C1 and opens valve C2. Pressure is relieved in the forward winch supply line 20 and PS1 resets, thereby providing latching power to relay C3. Valves C2, D2, and E2 are now open and the four way valve 18 is open/crossed and the drop action occurs as discussed in FIGS. 1 and 2. The drop action resets limit switch LS1, but this has no effect in relays B3, D4 or E3 because they are not latched and no effect on relay A3 or D3 because no pick up voltage is applied and no effect on relay F3 because no pick up voltage is applied. Because PS1 was reset when valve C2 opened, relays C3 and G3 are now supplied with latching voltage. 
     Resetting the system: Pressure switch PS2 senses pressure on the piston top chamber 16. When the piston has reached the bottom of the cylinder, pressure builds in the piston top chamber 16, pressure switch PS2 switches from the low pressure contact 32 to the high pressure contact P8. This breaks contact with the low pressure contact 32, and removes latching voltage from relays B3, D4 and E3 and de-energizes solenoids B1, D1 and F1. Contact with the high pressure contact P8 supplies pick up voltage to relays A3, C3, and F3 thus reinitiating the sequence. 
     The sequence repeats until the stop switch 34 is opened, thereby de-energizing all latching poles P3 and pick up poles P2.