JPH0715683U - Jack piston rod shortening device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] The present invention safely and easily removes the jack, which is the first work when dismantling the support in mountain retaining support work. [Structure] To allow the piston rod 6 of the jack to be artificially retracted into the cylinder tube 5 as necessary, connect the piston pedestal 8 and the cylinder tube 5 to the threaded bolt 1
They are tied at 0. In this case, one end of the threaded bolt 10 is fixed to the piston pedestal 8, and the other end of the cylinder tube 5 side is attached with a nut 7 at its free end. Then, when the nut 7 is rotated, a receiving member 12 that receives a reaction force necessary for the conversion is fixed to the outer surface of the cylinder tube 5 so that this rotational motion can be converted into the horizontal motion of the piston rod 6. In addition, this receipt 12
Is a perforated metal article that allows the threaded bolt 10 to pass freely.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for shortening the piston rod to the extent necessary for removing the jack, which is the first work when removing the support in the mountain retaining support work. One of the methods of underground excavation for constructing the underground part of civil engineering and construction structures is a method of combining a retaining wall and a retaining material. In this method, in order to prevent collapse of the mountain retaining wall due to excavation, as many as the number of steps corresponding to the depth of excavation, mountain retaining supports consisting of uprisings and beams are attached as the excavation progresses. At the time of installation, a jack is generally attached to the crossbeam mainly for the purpose of facilitating the removal work which is a post process. When the excavation is completed up to the specified depth, the construction of the structure proceeds from the bottom of the excavation to the ground, but when the structure rises up to near the lowest stage support, this support, that is, the uprising and the cut beam is constructed. It has to be removed because it becomes an obstacle to To enable this removal, the load previously supported by the support through the retaining wall is replaced by the already completed part of the structure. After that, all the underground parts will be constructed by repeating the same work procedure in sequence. A jack is required to facilitate the load transfer at this time, and the usual procedure for jack operation is to press the oil into the cylinder tube with an oil pump, release the stress of the lock nut, and That is, the piston is moved to the pedestal side and oil is discharged. This oil discharge means the release of the truss stress, and should eventually reach zero. However, in reality, the friction between the inner surface of the cylinder tube and the seal material attached to the piston rod does not reduce it to zero, and a small amount of stress remains, which requires a force that greatly exceeds the input force to remove the jack. And cause.

[0002]

[Prior art]

 At present, the following two methods are mainly used for this problem. One is to eliminate the resistance to removal by artificially shortening the piston rod slightly after the oil has been discharged. A hydraulic device for this purpose is provided by hollowing the piston rod. However, this method naturally raises the production cost and the maintenance cost due to the complicated structure. The other is a method of forcibly removing it using the mechanical force of a crane, etc. without any measures, but this method does not increase the manufacturing cost, but it is a work that involves a great deal of danger and causes an accident. ing.

[0003]

[Problems to be solved by the device]

 Focusing on the fact that the required shortening length to eliminate the resistance of jack removal is generally only a few centimeters, the piston rod can be operated by a simpler manual method without relying on an expensive and complicated hydraulic system. It is intended to enable shortening of.

[0004]

[Means for Solving the Problems]

 When the nut rotates around the bolt axis, the nut moves along with the bolt axis as it rotates. Thus, by using the screw mechanism, it is possible to convert rotational motion into horizontal motion. The present invention applies this principle, and by attaching several sets of screw mechanisms to the jack, the shortening of the piston rod, which is impossible with input, can be made extremely easy.

[0005]

[Action]

 Connect the cylinder tube and the base of the piston rod with several threaded bolts. At this time, one end of the bolt is fixed to the piston pedestal, and the other end is equipped with a nut, forming a free end by penetrating a perforated metal fixture fixed to the cylinder tube. When the nut is rotated in this state, the piston rod is drawn into the cylinder tube and shortened according to the amount of rotation.

[0006]

【Example】

 An embodiment will be described below with reference to the accompanying drawings. 1 is an uprising, 2 is a crossbeam, 3 is a jack, and 4 is a retaining wall. Reference numeral 5 is a cylinder tube of the jack, 6 is a piston rod, 7 is a lock nut, and 8 is a piston pedestal. Reference numeral 9 is a nut for fixing one end of the screw bolt, which is fixed to the piston base by welding or the like. 10 is a threaded bolt, 11 is a nut that rotates around the bolt, 12 is a metal receiving object that receives the reaction force necessary to convert the rotational movement of the nut into the shortening movement of the piston rod, and the bolt is located approximately in the center. There is a hole that allows free passage through, but one surface is fixed to the outer surface of the cylinder tube by welding or the like.

[0007]

[Effect of device]

 As described above, the piston rod shortening device to which the screw mechanism of the present invention is applied removes the jack without substantially increasing the manufacturing cost of the jack and the maintenance cost associated with the conventional hydraulic shortening device. Allows work to be performed safely and easily.

[Brief description of drawings]

FIG. 1 is a plan view of a mountain retaining support for underground excavation.

2 shows the cross section of FIG. 1, but for the sake of convenience, only the uppermost stage and the lowermost stage of the support are shown and the middle is omitted. The mountain retaining wall shown in this figure is omitted in FIG.

FIG. 3 is a side view of a jack attached to a cutting beam, but a connecting bolt to the cutting beam and a piston rod shortening device according to the present invention are omitted to avoid complicating the drawing.

FIG. 4 is an AA cross section of FIG. 3, showing an example in which two sets of shortening devices are attached.

5 is an enlarged view of the entire piston rod shortening device, taken along the line AA in FIG. 4, but the position of the lock nut is shown in FIG.
Unlike the above, it shows a state in which the piston has moved to the pedestal side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Uprising 2 Cutting beam 3 Jacking 4 Mountain retaining wall 5 Cylinder tube 6 Piston rod 7 Lock nut 8 Piston pedestal 9 Nut fixed to the piston pedestal 10 Threaded bolt 11 Nut that rotates around a threaded bolt 12 Receiving material

Claims (1)

[Scope of utility model registration request] 1. A device for shortening a piston rod of a jack, which utilizes an axial movement mechanism associated with rotation of a nut around a bolt axis.