Screw-type three stage jack

Abstract

To provide a three stage jack capable of extending / contracting quickly and in a short time.SOLUTION: A screw-type three stage jack comprises a rotation driving part 5 in a casing 1, a fixed cylinder 6 which is fixed upright on the rotation driving part 5 and becomes a first stage of a three stage jack, a rotary pipe screw 7 installed in the fixed cylinder and rotated by a rotating shaft 4, a nut block 9 for second stage formed to be liftable along the fixed cylinder 6 in the rotation restraint state due to fitting into the vertical groove on the inner surface of the fixed cylinder and screwed into the screw formed on the outer surface of the rotary pipe screw 7, a lifting cylinder 10 connected to the nut block 9 for the second stage, a nut block 11 for a third stage attached rotatably to the upper end part of the lifting cylinder, a lifting screw shaft 12 screwed into the nut block for the third stage, and a rotation transmission cylinder 13 to transmit the rotation of the rotary pipe screw 7 to the nut block 11 for the third stage. The lifting screw shaft 12 comprises a top plate 14 on its top edge and has the configuration that it is screwed into the nut block 11 for the third stage in its own rotation restraint state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a screw-type three-stage jack suitable for use in civil engineering and construction work as a support column for supporting necessary areas and lifting heavy objects, particularly for supporting temporary ceiling panels, etc. [Background technology]

[0002] 2. Description of the Related Art A screw-type "three-stage jack" in which a first-stage fixed cylinder houses a second-stage and a third-stage lifting cylinder has been known from the past, for example as disclosed in Patent Documents 1 and 2.

[0003] The screw-type three-stage jacks disclosed in these patent documents are configured to extend and retract with a long lifting stroke so that when the second stage lifting barrel is completed, the third stage lifting barrel begins to lift and retract. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 6-56092 [Patent Document 2] Japanese Patent Application Publication No. 7-172783 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned three-section jack, the third section lifts and lowers after the second section lifts and lowers, so although the lift stroke can be lengthened, there is a problem that the extension and contraction action takes time. In particular, in civil engineering and construction work, many long support columns that support temporary ceilings are used at the same time, so if the dimensions of each section of the above-mentioned jack are lengthened to use them as long support columns, the installation and removal work takes too much time, making it impractical.

[0006] Therefore, the object of the present invention is to provide a three-section jack that can extend and contract over a long lifting and lowering stroke, and can be efficiently extended and contracted quickly in a short period of time, thereby making it suitable for use as a long support column with a long lifting and lowering stroke. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides the following technical means. That is, the screw type three-stage jack of the present invention includes a rotary drive unit having a gear group and a rotary shaft built in a casing, a fixed cylinder that is fixed upright on the rotary drive unit and serves as the first stage of the three-stage jack, a rotary pipe screw that is disposed on the fixed cylinder and rotated by the rotary shaft of the rotary drive unit, a second-stage nut block that is fitted into a vertical groove on the inner surface of the fixed cylinder and is formed so as to be able to move up and down along the fixed cylinder while its rotation is restricted, and that screws into a thread formed on the outer circumferential surface of the rotary pipe screw, a lifting cylinder that is connected to the second-stage nut block and serves as a lifting member for the second stage, a third-stage nut block that is rotatably attached to the upper end of the lifting cylinder, a lifting screw shaft that is screwed into the third-stage nut block and serves as a lifting member for the third stage, and a rotation transmitting cylinder that transmits the rotation of the rotary pipe screw to the third-stage nut block, The lift screw shaft is provided with a top plate at its upper end, and is screwed into the third stage nut block with its own rotation restricted. Effect of the Invention

[0008] In the three-section jack of the present invention, the lifting cylinder, which is the lifting member of the second section of the jack, and the lifting screw shaft, which is the lifting member of the third section, move up and down simultaneously, and the lifting screw shaft moves up and down at approximately twice the speed of the lifting cylinder, so that the lifting cylinder and the lifting shaft can be raised and lowered quickly even if their lifting strokes are long. This makes it possible to extend and retract the jack in a short time, even if the jack is formed with a long lifting stroke, for example, a total length of 1500 mm when the jack is retracted and a total length of 3500 mm when fully extended, and thus the jack can be suitably used as a long support column for supporting temporary ceiling panels, etc.

[0009] In the above invention, a second stage cover tube which conceals the lifting tube and a third stage cover tube which conceals the lifting screw shaft are stored in the fixed tube in a manner that allows them to appear and disappear while being rotationally restricted, the second stage cover tube is configured to rise and fall together with the second stage nut block, and the third stage cover tube is fixed at its upper end to the top plate and configured to rise and fall together with the lifting screw shaft. As a result, when the jack is extended, the lifting tube and lifting shaft are hidden by the second stage cover tube and the third stage cover tube, improving the external aesthetics of the jack, and since the third stage cover tube is restricted from rotating, the rotation of the lifting screw shaft connected to it can also be restricted.

[0010] In the above invention, it is preferable that the rotating pipe screw is connected to the rotating shaft of the rotary drive unit via a rotating disk that receives its lower end, and a load detection unit is provided between the rotating disk and the casing so that the load applied to the jack can be detected. This makes it possible to accurately check the load on the jack, and when multiple jacks are used as support columns to support a temporary ceiling panel or the like, the load can be balanced to provide a balanced support. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a partially sectional front view showing the retracted position of the jack according to the present invention. [Diagram 2] FIG. 2 shows the state of the above-mentioned jack when extended, where (a) is an overall front view and (b) is an enlarged cross-sectional view of the main part. [Diagram 3] FIG. 4 is a front view of a main portion showing another embodiment of a jack according to the present invention. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a main part of the second embodiment. BEST MODE FOR CARRYING OUT THEINVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2 showing an embodiment thereof. FIG. 1 shows the jack in its retracted position, and FIG. 2 shows the jack in its fully extended position. The screw jack A of the present invention is equipped with a rotary drive unit 5 having bevel gears 2 and 3 and a rotary shaft 4 mounted inside a casing 1. The shaft 2a of the bevel gear 2 is exposed outside the casing and is connected to an electric motor (not shown). Note that it is also possible to connect a manual handle instead of the electric motor so that the jack can be rotated manually.

[0013] A fixed cylinder 6, which is the first stage of the three-stage jack, is fixed upright on the casing 1 of the rotary drive unit. The upper end of the fixed cylinder 6 is open, and a rotary pipe screw 7 is disposed inside. The rotary pipe screw 7 is interlocked and connected to the rotary shaft 4 via a rotary disk 8 that receives its lower end. A thread is formed on the outer circumferential surface of the rotary pipe screw 7, and a second-stage nut block 9 is screwed onto this thread. This nut block 9 is formed so that it can be fitted into a vertical groove formed on the inner surface of the fixed cylinder 6 and moved up and down along the vertical groove while its rotation is restricted.

[0014] In addition, a lifting cylinder 10 is provided which is connected to the second-stage nut block 9 and serves as a lifting member for the second stage of the jack. A third-stage nut block 11 is rotatably attached to the upper end of the lifting cylinder 10, and a lifting screw shaft 12 which serves as the third stage of the jack is screwed into this nut block 11. The lifting screw shaft 12 has a top plate 14 at its upper end, and is formed so as to rise and fall by the rotation of the third-stage nut block 11 while its own rotation is restricted by a means described later.

[0015] The third-stage nut block 11 is formed to rotate together with the rotation of the rotary pipe screw 7 via the rotation-transmitting cylinder 13. In detail, as shown in Fig. 2, the rotation-transmitting cylinder 13 is formed so that the engagement claws 7a of the rotary pipe screw 7 can vertically move and engage with the vertical grooves formed on the outer circumferential surface of the rotation-transmitting cylinder 13 to transmit rotation, and the upper end of the rotation-transmitting cylinder 13 is connected to the third-stage nut block 11 so as to be integrally rotatable, so that the blocks rotate simultaneously.

[0016] Furthermore, a second-stage cover tube 15 that hides the lift tube 10 and a third-stage cover tube 16 that hides the lift screw shaft 12 are provided so that they can be inserted and removed from the fixed tube 10 while being rotationally restricted. The second-stage cover tube 15 is formed so as to rise and fall together with the second-stage nut block 9, and the third-stage cover tube 16 is fixed at its upper end to the top plate 14 of the lift screw shaft 12. In the contracted position shown in FIG. 1, the upper end flange 15a of the second-stage cover tube 15 contacts the upper end surface of the fixed tube 6, and the upper surface of the flange 15a contacts the lower surface of the top plate 14, so that the contracted position is maintained. In addition, the second-stage cover tube 15 and the third-stage cover tube 16 maintain the external aesthetics when the jack is extended. In addition, the rotation of the third-stage cover tube 16 is restricted, so that the rotation of the lift screw shaft 12 connected thereto is also restricted.

[0017] 1, the length from the bottom surface of the casing 4 to the top plate 14 is 1500 mm, the lifting stroke of the lifting cylinder 10 which is the lifting member of the second stage of the jack is 1200 mm, and the lifting stroke of the lifting screw shaft 12 which is the lifting member of the third stage of the jack is 800 mm. This makes it possible to create a jack which is 1500 mm long when the jack is retracted, but can be extended up to 3500 mm, and which can be suitably used as a long support column for supporting a temporary ceiling.

[0018] Next, the operation of this jack will be described. When the rotary drive unit 5 is driven from the jack retracted position shown in FIG. 1, the rotary pipe screw 7 rotates via the rotary shaft 4 and the rotary disk 8. As a result, the second-stage nut block 9, which is rotationally restrained by the fixed cylinder 6, starts to rise together with the lift cylinder 10 and the third-stage nut block 11. As the third-stage nut block 11 rises, the lift screw shaft 12 screwed and held therein is also raised. At the same time, the rotation of the rotary pipe screw 7 is transmitted to the third-stage nut block 11 via the rotation transmission cylinder 13 and rotates synchronously, further pushing up the lift screw shaft 12 screwed therein. That is, the lift screw shaft 12 is screwed forward by the rotation of the third-stage nut block 11 while being raised together with the lift cylinder 10, so that it rises at approximately double the lift speed of the lift cylinder 10. As a result, even a long three-stage jack with a long extension stroke as described above can be extended in a short time. When the jack is to be retracted, the rotating shaft 4 is rotated in the reverse direction, so that each moving member performs the reverse operation to that described above, thereby enabling the jack to be quickly retracted.

[0019] As described above, in the three-section jack of the present invention, the lifting cylinder 10, which is the lifting member of the second section of the jack, and the lifting screw shaft 12, which is the lifting member of the third section, rise and fall simultaneously, and the lifting screw shaft 12 rises and falls at approximately double the speed of the lifting cylinder 10, so that even a three-section jack with a long lifting stroke, for example, a total length of 1500 mm when the jack is retracted and a total length of 3500 mm when fully extended, can be extended and retracted in a short time, and can be suitably used as a long support pillar for supporting temporary ceiling panels, etc. In addition, after use as a support pillar, it can be retracted compactly, making it convenient to carry and store.

[0020] In the present invention, as shown in Figs. 3 and 4, it is preferable to incorporate a load detection unit M for detecting the load applied to the jack between a rotary disk 8 connected to the rotary pipe screw 7 and the casing 1 of the rotary drive unit 5. In this embodiment, the load detection unit M has a disk-shaped piston body 17 and a cylinder body 18, and an oil-sealed oil chamber (cylinder chamber) 19 sealed with oil is provided between these bodies. In addition, the rotary disk 8 is placed on the upper surface of the piston body 17 to receive the load applied to the jack. The rotary shaft 4 of the rotary drive unit 5 is connected to the rotary disk 8 through the centers of the bodies 17 and 18. The piston body 17 is formed so as to be able to move up and down within a certain range relative to the cylinder body 18, and is constantly pushed upward by a plurality of springs 20. Furthermore, a pressure sensor 21 is provided in connection with the oil chamber 19, and a display unit 22 for calculating and displaying the measured pressure as a load value is provided outside the jack.

[0021] With the above configuration, when the jack is in use, the load on the rotating disk 8 presses the piston body 17, compressing the oil in the oil chamber 19. The pressure is detected by the pressure sensor 21 and displayed as a load value on the display unit 22. This has the effect of making it possible to accurately check the load on the jack, and when multiple jacks are used as support columns to support a temporary ceiling board or the like, it is possible to support it in a well-balanced manner with a balanced load.

[0022] Although the representative embodiment of the present invention has been described above, the present invention is not necessarily limited to the above embodiment. For example, the total length of the jack when it is retracted and when it is fully extended, and the lifting stroke of the lifting cylinder 10 which is the second stage of the jack and the lifting shaft 12 which is the third stage of the jack, can be changed and set as needed depending on the purpose and manner of use. In addition, the present invention can be appropriately modified and changed within the scope of the claims, while achieving its purpose. [Industrial Applicability]

[0023] INDUSTRIAL APPLICABILITY The screw type three-section jack of the present invention can be used in civil engineering and construction work as a support column for temporary ceiling panels, as well as for supporting areas where it is needed and for lifting heavy objects. [Explanation of symbols]

[0024] A Three-stage jack M Load detection unit 1 Casing 4 Rotation Axis 5 Rotation drive unit 6 Fixed barrel 7 Rotating Pipe Screw 8 Rotating Disc 9 Second stage nut block 10 Elevator 11 Third stage nut block 12 Lifting screw shaft 13 Rotation transmission cylinder 14 Tabletop

Claims

1. a rotation drive unit having a group of gears and a rotating shaft built in a casing; A fixed cylinder that is fixed upright on the rotation drive unit and serves as a first stage of the jack; a rotary pipe screw disposed in the fixed cylinder and rotated by a rotary shaft of the rotary drive unit; a second-stage nut block that is fitted into the vertical groove on the inner surface of the fixed cylinder and is formed so as to be movable up and down along the fixed cylinder while its rotation is restricted, and that is screwed into a thread formed on the outer circumferential surface of the rotary pipe thread; a lifting cylinder connected to the second stage nut block to serve as a second stage lifting member; A third stage nut block rotatably attached to the upper end of the lift cylinder; A lift screw shaft that is screwed into the third stage nut block to become a third stage lift member; a rotation transmitting tube for transmitting the rotation of the rotary pipe screw to the third stage nut block; The lifting screw shaft has a top plate at its upper end and is screwed into the third-stage nut block with its rotation restricted.

2. 2. The screw-type three-stage jack of claim 1, wherein a second-stage cover tube that conceals the lifting tube and a third-stage cover tube that conceals the lifting screw shaft are stored in the fixed tube in a manner that allows them to appear and disappear while being rotationally restricted, the second-stage cover tube is configured to rise and fall together with the second-stage nut block, and the third-stage cover tube is fixed at its upper end to the top plate and configured to rise and fall together with the lifting screw shaft.

3. 3. The screw-type three-stage jack according to claim 1 or 2, wherein the rotary pipe screw is connected to the rotary shaft of the rotary drive unit via a rotary disk that receives its lower end, and a load detection unit is provided between the rotary disk and the casing so that the load acting on the jack can be detected.

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