JPH0941375A - Hydraulic hammer - Google Patents

Abstract

(57) An object of the present invention is to provide a hydraulic hammer which can always drive a pile with an appropriate ram stroke without changing the ram stroke due to wear of a cushion provided on a cap put on the pile. SOLUTION: A plurality of detected parts N1 to N12 are arranged on a ram 2 at regular intervals in the vertical direction, and a detector 7 for detecting the detected parts is provided on a frame 1. When the ram 2 is raised, the number of detections by the detectors 7 of the detected parts N1 to N12 is counted, and when the number of detections reaches a set value, the electromagnetic switching valve 10 of the hydraulic cylinder 3 is switched to drop the ram. Detector 7
To a location shifted downward from a location on the frame 1 where the uppermost one N1 of the plurality of detected portions N1 to N12 can be detected by a distance equal to or more than a distance corresponding to a decrease in thickness due to wear of the cushion 6. I installed it. Alternatively, the detector 7 is attached to a position below it so as to be shiftable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic hammer in which a ram in a frame is lifted by a hydraulic cylinder and then dropped to drive a pile.

[0002]

2. Description of the Related Art A pile driving machine using a hydraulic hammer is constructed such that a vertical pile is drilled by an auger which is vertically moved and driven to rotate along a leader attached to the main body of the pile driving machine. The ram in the frame that is lifted up and down is lifted with a hydraulic cylinder to free fall or urged to drop, and the ram is struck through the cap with a cushion to repeat the operation to lift the pile. It is something to drive in.

In such a hydraulic hammer, the stroke of the ram is increased when the soil is hard, and the stroke of the ram is reduced when the soil is soft, so that the pile is driven with an appropriate striking force according to the soil. Is being done. As a means for changing this stroke, a plurality of detectors for detecting the upper end position of the ram are arranged on the frame at intervals above and below corresponding to various strokes, and the output signals of these detectors are selected. The method of selecting a stroke by the method, or as disclosed in Japanese Patent Laid-Open No. 59-80819, the ram is provided with detected parts such as unevenness at equal intervals in the vertical direction and the uppermost part of the detected part. One detector is provided at a location on the frame facing to, and the number of detections by the detector of the detected portion after the start of the ram rise is counted, and when the count value becomes the set value commensurate with the stroke. There is a method of switching the hydraulic circuit of the hydraulic cylinder to change the ram from rising to falling.

[0004]

When the pile is driven by using the conventional hydraulic hammer as described above, when the pile is driven into a very hard special soil, the upper surface of the cap to be put on the top of the pile is used. The cushion provided on the floor is worn, for example, the one with a thickness of about 10 to 20 cm in the initial stage is about 2 to 3 cm.
It turned out that it may become extremely thin to some extent. When the cushion becomes extremely thin, the position of the ram when the ram collides with the cushion is much lower than it was before the cushion was worn, so the stroke corresponding to the output signal of the detector is actually measured. Will be longer than. In this way, if the stroke becomes longer than the preset value, the following problems occur. 1) In the case of concrete pile driving, there is an appropriate ram stroke according to the pile and soil quality.
There is a risk that the pile will crack due to excessive impact force. 2) Since the ram stroke is longer than the proper stroke, the rising time and the falling time are long, the number of hits is small, and the planned pile supporting force may not be obtained. (The supporting force of the pile is calculated by the sinking amount of the pile to be hit, the weight of the ram and the stroke.) 3) The fall time is set by a timer for each stroke, and the ram is set after each drop time has elapsed. If the stroke is longer when the operation control to start the ascent of the ram is performed, the actual fall time becomes longer than the set fall time, and the ram may be falling at the start of the ram rise. In that case, the falling energy of the ram and the pressure oil from the hydraulic pump on the main body of the pile driver may collide with each other to damage the hydraulic cylinder for raising the ram.

In view of the above-mentioned problems, the present invention provides a hydraulic hammer in which the ram stroke does not change due to wear of the cushion provided on the cap that covers the pile, and the pile can always be driven with an appropriate ram stroke. The purpose is to do.

[0006]

In order to achieve the above object, the present invention accommodates a ram to be lifted and dropped by a hydraulic cylinder in a frame, and mounts a cap with a cushion for covering the top of a pile on the lower part of the frame. Then, a plurality of detected parts are arranged on the ram at regular intervals in the vertical direction, and a detector for detecting the detected parts is provided on the frame, and a detector for the detected parts when the ram is raised. In a hydraulic hammer having a control device that counts the number of detections by, and switches the hydraulic circuit of the hydraulic cylinder to drop the ram when the number of detections reaches a set value, the detector is
The uppermost one of a plurality of detected parts is shifted to a position shifted downward from a position on the frame where it can be detected by a distance equal to or smaller than the thickness reduction due to the wear of the cushion, or to a position below the same. It is characterized by being installed as much as possible.

[0007]

According to the present invention, the ram is provided with a plurality of parts to be detected in the vertical direction, the frame is provided with a detector, and the number of detections of the parts to be detected of the detector after the ram is started to rise is counted and When the count value reaches the set value, control is performed to start dropping the ram. In addition, assuming that the cushion will wear in advance, the position of the detector can be lowered or adjusted so that it can be lowered more than the amount of wear. The counting operation of the part is performed accurately, and the wrong stroke is not detected,
Always work with accurate ram strokes.

[0008]

1 is an overall view showing an embodiment of a hydraulic hammer according to the present invention. In FIG. 1, reference numeral 1 is a frame that is lifted and lowered along a leader (not shown) of a pile driver, and 2 is a ram that is housed in the frame 1 so as not to rotate and is vertically movable.
Reference numeral 3 is a hydraulic cylinder for lifting the ram, and there is also a hydraulic cylinder 3 provided outside the frame 1 for moving the ram 2 up and down via a wire. Reference numeral 4 denotes a cap that covers the top of the pile 5, and reference numeral 6 denotes a cushion attached to the upper surface of the cap 4, which is made of hard wood such as oak. The cap 4 is fitted and attached to the lower portion of the frame 1, and is supported by a chain having a slack (not shown) so as not to fall from the frame 1.

Reference numeral 7 denotes a detector formed of a proximity switch provided on the frame 1, and N1, N2, ... N12 denote detection portions formed on the opposing surface of the detector 7 of the iron ram 2 and having irregularities. Assuming that the cushion 6 is worn, the detector 7 wears the cushion 6 from the position a corresponding to the uppermost detected portion N1 when the ram 2 is in the lowered position (50% to 100% of the thickness of the cushion 6). %) Position b (ab = Δ)
L). In this example, ΔL is set to a distance slightly larger than the thickness t of the cushion 6 (wear amount 100%).

Reference numeral 9 is a hydraulic pump mounted on a pile driver main body (not shown), and 10 is an electromagnetic switching valve for switching the hydraulic circuit of the hydraulic cylinder 3, which inputs the output of the detector 7. When the control device 11 energizes the solenoid 10a, the electromagnetic switching valve 10 is switched to the left position, pressure oil from the hydraulic pump 9 is supplied to the rod chamber of the hydraulic cylinder 3, the hydraulic cylinder 3 contracts, and the ram 2 is lifted. When the energization of the solenoid 10a is stopped, the electromagnetic switching valve 10 returns to the right position, the oil in the rod chamber of the hydraulic cylinder 3 flows into the oil tank 12, and the hydraulic cylinder 3 falls freely.

In this apparatus, a case will be described in which the ram 2 is raised and lowered by 7 steps of the detected portion when the cushion 6 has a normal thickness and is not worn. As shown in FIG. 1, when the ram 2 is descending, in this embodiment, the detector 7 is the fourth detected portion N from the top.
It is in a position facing 4. From this state, the control device 11 switches the electromagnetic switching valve 10 to the left position to move the hydraulic pump 9
When the hydraulic oil from the pump is supplied to the rod chamber of the hydraulic cylinder 3 to lift the ram 2, the detector 7 sends a detection signal corresponding to the detected portion having unevenness to the control device 11, and the control device 11
Counts the number of detections. Then, as shown in FIG.
When the number of detected parts N11 (7) corresponding to the stroke L7 is reached, the control device 11 switches the electromagnetic switching valve 10 to the right position. As a result, the oil in the rod chamber of the hydraulic cylinder 3 flows into the oil tank 12 and the ram 2 drops.

Next, when the cushion 6 wears and the thickness becomes thin, as shown in FIG. 3, the detector 7 in this example is the second uppermost detected portion in the lowered state of the ram 2. It is located at a position corresponding to N2. From here the control device 11
Thus, the solenoid 10a of the electromagnetic switching valve 10 is energized to switch the electromagnetic switching valve 10 to the left position to raise the ram 2. After the start of the ascent, the control device 11 counts the detection signals from the detector 7 and, as shown in FIG. 4, matches the position where the ninth detected portion N9 from the top faces the detector 7, that is, the stroke L7. Solenoid 10 of solenoid operated directional control valve 10
The energization to a is stopped, whereby the electromagnetic switching valve 10 returns to the right position, and the ram 2 drops with the stroke L7.

As described above, even if the position of the ram 2 when it descends changes due to the wear of the cushion 6, the set ram stroke does not change. Therefore, there is no possibility that the pile 5 is cracked by an excessive impact force. Therefore, the rising time and the falling time are as set, and the number of hits does not decrease, and the designed pile supporting force can be obtained. Also, if the fall time of the ram 2 is adjusted with a timer,
It is possible to prevent damage to the hydraulic cylinder 3 due to the timer setting time being over due to overstroke, and it is not necessary to reset the timer time due to wear of the cushion 6.

FIG. 5A is an overall view showing another embodiment of the present invention, and FIG. 5B is a front view for explaining the detector mounting structure. The detector 7 is fixed on the frame 1. Instead of mounting at a point, a distance corresponding to a reduction in thickness due to wear of the cushion 6 from a point a on the frame at a height at which the uppermost one N1 of the detected portions N1 to N12 of the ram 2 can be detected. The detector 7 is attached so that the position can be adjusted over the range of the position b shifted downward.
That is, the detector mounting seat 13 fixed to the frame 1 is provided with a plurality of screw holes 13a to 13d arranged vertically, and the bolt 14 passed through the mounting piece 7a of the detector 7 is inserted into these holes 13a to 13d. The mounting position of the detector 7 can be changed by screwing and tightening one of them. In this way, by adjusting the position of the detector 7 according to the wear of the cushion 6, the same effect as described above can be obtained. When the cushion 6 that is considerably thicker than the normal cushion is used, the detector 7
The stroke can be secured by setting the position of to a high position.

FIG. 6 is an overall view of another embodiment of the present invention. The detector 7 shown in FIG. 1 (that is, the uppermost one N1 of the plurality of detected portions N1 to N12 can be detected). A detector mounted at a position shifted downward from a position on the frame 1 by a distance corresponding to a reduction in thickness due to wear of the cushion 6), or the uppermost one of the detected parts of the ram. A detector 7X is also provided at a position where N1 can be detected, and output signals of these detectors 7 and 7X are switched by a switch 15
It is selected by and input to the control device 11.

According to the present embodiment, by connecting the switch 15 to the detector 7 on the lower side, the same effect as that of the embodiment of FIGS. 1 to 4 can be obtained. Further, when the cushion 6 that is considerably thicker than a normal cushion is used, the stroke can be secured by selecting the detector 7X at a high position. Further, according to the present embodiment, by providing the switch 15 in the driver's cab (not shown) on the main body of the pile driver, the detector can be easily selected, and the position adjustment work as in the case of FIG. 5 is unnecessary. Has the advantage that In the embodiment of FIGS. 5 and 6, the ram 2 is attached to the frame 1.
By providing a window for visually observing the height of the cushion 6, the degree of wear of the cushion 6 can be confirmed from the outside.

In the present invention, the detectors 7 and 7x are not limited to those that magnetically detect the detected portion,
A method of optically detecting the detected portion can be used. The lower limit position for mounting the detector 7 is the maximum stroke Lmax set by the hydraulic hammer.
Is the lowest detected portion Nmax (N1 in the above embodiment).
2) to a mounting position Ni of the detector 7 (a position corresponding to the detected portion N4 in the above-described embodiment), which is smaller than or equal to the stroke, that is, Lmax ≦ N
Set to max-Ni.

[0018]

According to the first aspect of the present invention, the mounting position of the detector on the frame is set on the assumption that the cushion becomes thin due to wear of the cushion.
It is possible to detect the stroke in the same manner as in the state where no wear occurs.
Therefore, there is no risk that the pile will crack due to excessive impact force.
Also, the designed pile bearing capacity as planned can be obtained. Also, when the ram drop time is adjusted by a timer, etc., it is possible to prevent damage to the hydraulic cylinder due to the timer setting time being over due to overstroke, and it is not necessary to reset the timer time when the cushion is worn. .

[Brief description of drawings]

FIG. 1 is an overall view showing an embodiment of a hydraulic hammer according to the present invention.

FIG. 2 is an overall view showing a state when the ram is raised in the embodiment of FIG.

FIG. 3 is an overall view showing a lowered state of a ram after the cushion is worn in the present embodiment.

FIG. 4 is an overall view showing a state when the ram is raised after the cushion is worn in the present embodiment.

5A is an overall view showing another embodiment of the hydraulic hammer according to the present invention, and FIG. 5B is a front view showing the detector mounting structure thereof.

FIG. 6 is an overall view showing another embodiment of the hydraulic hammer according to the present invention.

[Explanation of symbols]

1: Frame, 2: Ram, 3: Hydraulic cylinder, 4: Cap, 5: Pile, 6: Cushion, 7, 7X: Detector, 7
a: mounting piece, 9: hydraulic pump, 10: electromagnetic switching valve, 1
1: Control device, 12: Oil tank, 13: Detector mounting seat, 14: Bolt, 15: Switch

Claims (1)

[Claims] 1. A ram that is lifted and dropped by a hydraulic cylinder is housed in a frame, and a cap with a cushion that covers the top of a pile is attached to the lower part of the frame, and a plurality of rams are vertically spaced at regular intervals. And the detector for detecting the detected portion is provided in the frame, the number of detections by the detector of the detected portion is counted when the ram is raised, and the detected number reaches the set value. Then, in a hydraulic hammer having a control device for switching the hydraulic circuit of the hydraulic cylinder to drop the ram, the detector is a cushion from a position on the frame where the uppermost one of the plurality of detected parts can be detected. A hydraulic hammer characterized in that the hydraulic hammer is shiftably mounted at a position shifted downward by a distance corresponding to a decrease in thickness due to wear of the same or at a position lower than the distance.