JPS6138286B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drop hammer whose weight is actuated by a hydraulic cylinder.

With respect to a drop hammer, for example, a ram having an upwardly directed cylinder and piston member, a conduit device for connecting the internal spaces of the cylinders on both sides of the piston in such a manner that fluid flow occurs in these spaces, and a conduit device for connecting the cylinder spaces to each other. an isolating conduit valve arrangement, the valve being moved by increasing pressure in one of said spaces to interrupt said flow, thereby preventing the introduction of pressurized fluid into another one of said spaces; British Patent No. 1,261,220 discloses a drop hammer configured to cause relative movement between a cylinder and a piston. To describe the valve device in this drop hammer in detail, the spool is slidably fitted into a cylindrical hole formed in the piston, the boat forming the passage between the spool and the piston, and the spool connected to the piston. The valve spring biases the passage in the direction in which it is opened. When the pressure in the space at the upper end of the cylinder is increased, the spool moves against the valve spring and blocks the passage.

In such a drop hammer that is actually in operation, the valve spring is
It consists of a long coiled spring, and has a double spring structure to provide the necessary biasing force to the spool.

However, a problem with the drop hammer as described above is that the valve device is easily damaged. In other words, the valve may be damaged in the early stages of use, or
The valve spring, especially the outer valve spring, is easily broken in the gap between the spool and the piston.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic drop hammer with improved valve durability, and in particular with improved durability of the outer valve spring.

To achieve this objective, the hydraulic drop hammer of the present invention includes a cylinder, a piston housed inside the cylinder, a spool slidably housed in a cylindrical hole provided in the piston, and a piston and a spool. a passageway which is drilled through the spool and which is opened and closed in relation to the sliding of the spool to allow oil to move in the space within the cylinder on both sides of the piston when opened; A spring receiving hole is formed in the bottom wall of the cylindrical hole of the piston, and a groove is formed in the lower end surface of the spool, and one spring holder is inserted into the groove. and the other spring receiver is arranged in each of the spring housing holes, the coil spring is interposed between both spring receivers, and a spring rod is provided inside the coil spring to guide the displacement of the coil spring. The coil spring is provided with an end turn portion at each end thereof, and the coil spring is characterized in that at least a portion of the spring between the end turn portions is accommodated in the spring housing hole. .

An embodiment of the present invention will be described below with reference to the drawings.

In Figures 1 and 2, the hydraulic drop hammer has a frame body installed on the pile or steel pipe (not shown) to be driven, and a frame body 1 that is attached to the frame body 1 and placed over the top end of the pile or steel pipe. It is equipped with a cap 2. The weight 3 is moved vertically within the frame 1 by a hydraulic cylinder device 4. The hydraulic cylinder device 4 has an upper end of the cylinder 40 connected to the frame 1, and a piston rod 4.
1 is connected to a weight 3. The connecting portion between the piston rod 41 and the weight 3 is provided with a shock absorbing member such as a rubber plate. The upper end of the piston rod 41 is connected to a piston 42 housed within the cylinder 40. Conduits K1 and K2 of the hydraulic circuit are connected to the space A on the upper end side of the piston 42 via ports 43 and 44 bored in the cylinder 40, respectively, and the space B on the lower end side of the piston 42 is connected to the cylinder 40. A conduit K3 of the hydraulic circuit is connected via the drilled port 45.

A cylindrical hole 50 that opens into the space A is formed in the piston 42, and a spool 51 is inserted into the cylindrical hole 50.
is slidably housed. and spool 5
Ports 52 and 53 are formed in the piston 1 and the piston 42, respectively, and these ports form passages through which the spaces A and B can communicate with each other.

Further, a coil spring serving as a valve spring is installed in a compressed state between the spool 51 and the piston 42, and the spool 51 is biased in the direction in which the passage is opened. When the spool 51 moves to the illustrated position where the passage is open, a stopper 5 provided on the inner wall of the cylindrical hole 50 at the upper end of the piston 42
4 and prevents further movement. The coil spring is composed of two coil springs 60 and 61 in order to obtain a biasing force. The coil spring 61 is installed on the inside, and the coil spring 60 is installed on the outside.

In the present invention, breakage of the outer coil spring 60 is prevented. It is the outer coil spring 6
The above-mentioned breakage is prevented by taking measures to prevent buckling.

Therefore, in this embodiment, the outer coil spring 60
An end turn portion is formed at each end of the spool, and the end turn portion on the spool side is formed between the lower end surface of the spool and the bottom wall of the cylindrical hole of the piston when the spool moves in the direction of opening the passage. The structure is such that the entire coil spring is prevented from being deformed in a direction different from the correct direction of expansion and contraction.

That is, the outer coil spring 60 has a portion of the spring wire that is the element of the coil spring at both ends, and the end portions 60A and 60B are formed where the spring wires are always in contact with each other. has been done. The outer coil spring 60 and the inner coil spring 61 are interposed between the spring receiver on the spool side and the spring receiver on the piston side.

To explain in detail the structure including both the coil springs 60 and 61, a groove 62 is formed in the lower end surface of the spool 51, and one spring receiver 63 is fitted into the groove 62. Further, a coil spring receiving hole 64 is bored along the axis of the piston 42 from the bottom wall of the cylindrical hole 50 of the piston 42 to a part of the piston rod 41, and the other spring receiver 65 is fitted into the bottom of the hole 64. There is. A spring rod 66 consisting of a large diameter portion 66A and a small diameter portion 66B is provided at the center of the spring receiver 63, and a spring rod 66 consisting of a large diameter portion 66A and a small diameter portion 66B is provided at the center of the spring receiver 65.
A cylindrical portion 65 is provided in which the small diameter portion 66B of the spring rod 66 is inserted. The small diameter portion 66B of the spring rod 66 is connected to the cylindrical portion 65 of the spring receiver 65.
A and the hole 65 are fitted into each other, and a retaining nut 67 is screwed onto the shaft end protruding from the spring receiver 65.

The inner coil spring 61 described above is the spring rod 6.
6, and its upper end is connected to the large diameter portion 66A and the small diameter portion 66 of the spring rod 66.
B, and the lower end thereof is brought into contact with the end surface of the cylindrical portion 65A of the spring receiver 65, respectively.

Further, the outer coil spring 60 is connected to the spring rod 6
The large diameter portion 66A of 6 and the cylindrical portion 6 of the spring receiver 65
arranged around the coil spring 61 containing 5A;
The upper end of the end turn portion 60A is brought into contact with the spring receiver 63, and the lower end of the end turn portion 60B is brought into contact with the spring receiver 65, respectively. Then, an end turn portion 60 at the upper end of the coil spring 60
A is the number of end turns that occupies the gap formed between the lower end surface of the spool 51 and the bottom surface of the cylindrical hole 50 of the piston 42 when the spool 51 moves to the position where the passage is opened. In other words, when the passage is opened in the spool 51, the rest of the coil spring 60 except for the upper end turn portion 60A is inserted into the spring accommodation hole 60.
All of the inner coil springs 61 are accommodated in the spring housing hole 64 . In a similar state, the inner surface of the inner coil spring 61 is in contact with the small diameter portion 66B of the spring rod 66. The outer coil spring 60 has its upper end turn portion 6
The outer surface of the portion other than 0A contacts the inner surface of the accommodation hole 64, the inner surface of the upper end turn portion 60A contacts the large diameter portion 66A of the spring rod 66, and the inner surface of the lower end turn portion 60B contacts the cylinder of the spring receiver 65. They are in contact with the portions 65A, respectively.

Furthermore, when the spool 51 moves to the position where the passage is closed, the outer surface of the upper end turn portion 60A of the outer coil spring 60 is guided by the inner surface of the groove 62 of the spool 51 and the inner surface of the spring accommodation hole 64. ing.

The number of end turns of the upper end turn portion 60A of the outer coil spring 60 is determined by the size of the gap formed between the spool 51 and the piston 42; , the number of end turns in the lower end turn section is 10 each.

Next, the operation of the hydraulic drop hammer according to the present invention will be explained. First, the frame 1 is installed with the cap 2 placed over the top of the pile (or steel pipe).
In this state, the piston 42 of the cylinder device 4 is located at the lower part of the cylinder 40, and the spool 51 is located at the stopper 54 of the piston 42.
It is located in a position where it is in contact with, that is, where the passage is open. Next, the directional control valve V in the hydraulic circuit
1 is switched from the neutral position shown in the figure to the a position, pressure oil flows from the hydraulic pump P1 to the conduit K3 and the port 45.
It is supplied to the lower space B of the cylinder 40 via. This pressure oil flows into the upper space A through the ports 53 and 52 of the piston 42 and the spool 51, but the flow from the space A to the oil tank T1 continues until the pressure from the port 43 reaches 3 kg/cm ² . The pressure release valve V2 prevents oil from returning to the oil tank T1. Said pressure relief valve V2 is provided in conduit K4 which bypasses check valve V3 provided in conduit K1. Further, the flow of oil to the oil tank T1 in the conduit K1 is blocked by the check valve V3,
The flow of oil through the conduit K2 is blocked by a check valve V4 provided in the conduit K2. As a result, the pressure in the upper space A of the cylinder 40 increases, and when this pressure overcomes the spring force of the inner and outer coil springs 61 and 60 and the friction acting on the spool 51, the spool 51 compresses the coil springs 60 and 61. It descends and the ports 52 and 53 are blocked, that is, the passage is closed. During this time, the pressure oil from the hydraulic pump P1 continues to flow into the lower space B of the cylinder 40, so the piston 42 begins to move up inside the cylinder 40 together with the weight 3. When the piston 42 reaches the set stroke, the directional control valve V1 is switched to the neutral position and the lower space B of the cylinder 40 is connected to the oil tank T1 via the conduit K5. As a result, a pressure drop occurs in the lower space B and the piston 42
And the weight 3 falls. At this time, as the volume of the upper space A increases, the pressure in the space A decreases, and the spool 51 rises again to the position where it comes into contact with the stopper 54 due to the spring force of the coil springs 60, 61, and the ports 52, 53 Upper and lower space A,
B is connected. This means that in addition to the oil expelled from the lower space B being returned to the oil tank T1 via the port 45 and the conduit K5, the two ports 52,
53 into the upper space A and the piston 42
The weight 3 falls freely without being subjected to falling resistance.

In addition, when the volume of the upper space A rapidly increases due to the fall of the piston 42 and the weight 3, the oil from the oil tank T1 flows into the space A from each conduit K1, K.
2 and each port 43, 44, negative pressure is prevented, but in order to reliably prevent insufficient suction of oil, in the illustrated example, each conduit K
1. Make-up tank T2 is located at or near the connection between K2 and conduit K6 that connects to oil tank T1.
is installed so that the oil in the tank T2 is sucked into the upper space A.

In the illustrated hydraulic circuit, a pilot type directional control valve is used as the directional control valve V1, and an electromagnetic pilot valve is used as the pilot valve V5 for switching the directional control valve V1. In other words, the pilot valve V5 is configured to be switched by a timer or the like. For example, when the pilot valve V5 is switched from the neutral position shown in the drawing to the b position, pressure oil (pilot pressure oil) flows from the hydraulic pump P2 through the conduit K7. Then, when the pilot valve V5 is switched to the position c, pressure oil flows through the conduit K8 to the other side of the directional control valve V1. The directional control valve V1 is configured to be switched to the neutral position by acting on the control section.

As described above, in the present invention, when the coil springs 60 and 61 are displaced (expanded and contracted) in accordance with the movement of the spool 51, the outer surface of the upper end turn portion 60A of the outer coil spring 60 is in contact with the inner surface of the concave groove 62 of the spool 51 and the spring. The outer surface of the other portions is guided by the inner surface of the spring accommodation hole 64, and the inner surface of the upper end turn portion 60A is guided by the large diameter portion 66A of the spring rod 66, and the lower end turn portion is guided by the large diameter portion 66A of the spring rod 66. 60B
The inner surface of the outer coil spring 60 is guided by the cylindrical portion 65A of the spring receiver 65, and the inner surface of the spring portion between the upper and lower end turn portions is guided by the inner coil spring 61, thereby preventing buckling of the outer coil spring 60. ing. That is, when a general long coil spring is compressed, the average diameter of the spring coil increases. Therefore, if only the inner surface of the coil spring is guided by a spring rod, when compressed, the average diameter of the spring coil increases as described above, creating a gap between the coil spring and the spring rod, and the coil spring will buckle in the gap. Become.

However, in the present invention, when the outer coil spring 60 is compressed, its inner and outer surfaces are guided to suppress an increase in the average diameter of the spring coil.
Since no gap is created between 0A and the large diameter portion 66A of the spring rod 66, buckling of the outer coil spring 60 is prevented. As a result, the outer coil spring 60
Breakage of the coil spring 60 is prevented, and the durability of the coil spring 60 is improved.

Further, the inner surface of the inner coil spring 61 is guided by the small diameter portion 66B of the spring rod 66, and the outer surface is guided by the inner surface of the outer coil spring 60.

In addition, in FIG. 2, the cylindrical hole 5 of the piston 42
A buffer 46 is provided on the bottom wall to cushion the impact when the spool 51 descends.

Another embodiment of the invention is shown in FIG. This embodiment differs from FIGS. 1 and 2 in that the spool 51 moves relative to the piston 42, and a gap is formed between the lower end surface of the spool 51 and the bottom wall of the cylindrical hole 50 of the piston 42. Also, the outer coil spring 160 is not exposed in the gap.

To explain in detail, a groove 162 is formed in the lower end surface of the spool 51, and one spring receiver 163 is fitted into the groove 162. Also piston 4
A coil spring receiving hole 164 is provided along the axis of the piston 42 from the bottom wall of the second cylindrical hole 50 to a part of the piston rod 41, and the other spring receiver 165 is fitted into the bottom of the hole 164. The spring receiver 163 has a spool 51 connected to the ports 52 and 53.
The spring receiving surface 163A is located near the open end of the spring receiving hole 164 in a state where a gap is formed between the lower end surface of the spool 51 and the bottom wall of the cylindrical hole 50 of the piston 42. It is becoming. Further, a spring rod 166 consisting of a large diameter portion 166A and a small diameter portion 166B is provided at the center of the spring receiving surface of the spring receiver 163.
5 is provided with a hole into which the small diameter portion 166B of the spring rod 166 is inserted, and a cylindrical shaft 165A into which the small diameter portion 166B is inserted. The small diameter portion 166B of the spring rod 166 is connected to the cylindrical portion 165 of the spring receiver 165.
A locking nut 167 is fitted into the hole A and is screwed onto the shaft end protruding from the spring receiver 165.

The coil spring that biases the spool 51 is also composed of an outer coil spring 160 and an inner and outer coil spring 161 in this embodiment, and an inner coil spring 16
1 is arranged around the small diameter portion 166B of the spring rod 166, and has its upper end at the step between the large diameter portion 166A and the small diameter portion 166B of the spring rod 166, and its lower end at the end surface of the cylindrical portion 165A of the spring receiver 165. It is in contact.

The outer coil spring 160 has several end turns 160A and 160B formed at both ends thereof, and the large diameter portion 166A of the spring rod 166 and the spring receiver 16.
The coil spring 16 includes a cylindrical portion 165A of 5.
are arranged around 1. And the upper end winding part 1
The upper end of 60A is connected to the spring receiving surface 163A of the spring receiver 163.
and the lower end of the lower end turn portion 160B is connected to the spring receiver 16.
5, respectively. That is, the outer coil spring 160 is housed in the spring housing hole 164 and is interposed between the spring receivers 163 and 165, and when the spool 51 is moved, the lower end surface of the spool 51 and the piston 42 are Even if a gap is formed with the bottom wall of the cylindrical hole 50, it will not be exposed.

Further, the entire outer surface of the outer coil spring 160 contacts the inner surface of the spring housing hole 164, the inner surface of the upper end turn portion 160A contacts the large diameter portion 166A of the spring rod 166, and the inner surface of the lower end turn portion 160B contacts the inner surface of the spring housing hole 164. They are respectively in contact with the cylindrical portion 165 of the spring receiver.

The inner coil spring 161 is in contact with the small diameter portion 166B of the spring rod 166 on its entire inner surface.

In this embodiment, when the coil springs 160 and 161 are displaced (expanded and contracted) in accordance with the movement of the spool 51, the entire outer surface of the outer coil spring 160 is guided by the inner surface of the spring accommodation hole 164, and the upper and lower end turns The inner surfaces of 160A and 160B are the large diameter portion 160A of the spring rod 166 and the cylindrical portion 1 of the spring receiver 165.
65A, and the inner surface of the spring portion between the upper and lower end turns is guided by the inner coil spring 161, thereby preventing the outer coil spring 160 from buckling. That is, when the outer coil spring 160 is compressed, the increase in the average diameter of the spring coil is suppressed, thereby preventing the coil spring 160 from buckling. As a result, the outer coil spring 160 is prevented from breaking and the durability of the coil spring 160 is improved.

Further, in this embodiment, the outer coil spring 160 is connected to the spool 51 and the cylindrical wall of the piston 42.
0 Since it is not exposed in the gap between the spool 51 and the bottom wall, in the event that the outer coil spring 160 breaks during long-term use, the broken pieces will not scatter into the gap, and when the spool 51 descends. There is also the advantage that the buffer 46 that cushions the impact will not be damaged.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention,
FIG. 1 is an explanatory diagram showing the overall configuration of a hydraulic drop hammer including a hydraulic circuit, FIG. 2 is a detailed cross-sectional view of the cylinder portion in FIG. 1, and FIG. 3 is a detailed view of the cylinder portion in another embodiment of the present invention. FIG. 4...Cylinder device, 40...Cylinder, 42
... Piston, 50 ... Cylindrical hole, 51 ... Spool, 52, 53 ... Port, 60 ... Outer coil spring, 60A, 60B ... End turn portion of outer coil spring, 61 ... Inner coil spring, 62... Concave groove, 6
3, 65... Spring holder, 64... Spring accommodation hole, 66
...Spring rod, 66A... Large diameter part of spring rod, 66B... Small diameter part of spring rod, 190...
...Outer coil spring, 160A, 160B...End turn portion of outer coil spring, 161...Inner coil spring, 162...Concave groove, 163, 165...Spring receiver, 164...Spring accommodation hole, 166...Spring Rod, 166A...Large diameter part of spring rod, 166
B... Small diameter part of the spring rod, A, B... Space inside the cylinder.

Claims (1)

[Claims] 1. A cylinder, a piston housed inside the cylinder, a spool slidably housed in a cylindrical hole provided in the piston, and a hole formed between the piston and the spool, a passageway that opens and closes in conjunction with the sliding of the spool and causes oil to move in the space within the cylinder on both sides of the piston when opened;
A coil spring biases the spool in the direction in which the passage is opened, and a spring receiving hole is provided in the bottom wall of the cylindrical hole of the piston, and a groove is provided in the lower end surface of the spool. disposing a receiver in the groove and the other spring receiver in the spring housing hole, interposing the coil spring between both spring receivers;
A spring rod for guiding the displacement of the coil spring is provided inside the coil spring, and end turns are formed at both ends of the coil spring, and the coil spring is arranged at least between the end turns. A hydraulic drop hammer characterized in that up to the spring portion of the hammer is housed in a spring housing hole. 2. The end turn portion on the spool side of the coil spring has the number of end turns that exists in the gap between the lower end surface of the cylinder and the bottom wall of the cylindrical hole of the piston, and when the spool is moved, the outer surface of the end turn portion 2. The hydraulic drop hammer according to claim 1, wherein the drop hammer is guided by the inner surface of the concave groove of the spool and the inner surface of the spring housing hole, and the inner surface is guided by a spring rod. 3. The spring receiver on the spool side is arranged so that when the spool moves to the position where the passage is opened and a gap is formed between the lower end surface of the spool and the bottom wall of the cylindrical hole of the piston, the spring receiver surface is connected to the spring receiving hole. It is a spring receiver located near the open end of the coil spring, and when the spool is moved, the entire outer surface of the end turn portion of the coil spring is guided by the inner surface of the spring housing hole, and the inner surface is guided by the spring rod portion. A hydraulic drop hammer according to claim 1.