CN1026395C - Manufacturing method and device for prefabricated hollow concrete piles - Google Patents

Abstract

A method and apparatus for manufacturing a precast hollow concrete pile. Concrete is poured outside a tubular component while it is in a radially expanded state. A retaining device is used to retain the tubular component. After the concrete solidifies, the radially contracted tubular component is pulled out. Thus, the tubular component used to form the hollow portion can be simply retained and easily pulled out of the hollow portion.

Description

The present invention relates to a method and apparatus for making prefabricated hollow concrete piles for foundations of various building structures.

Regarding concrete piles, there are prefabricated concrete piles that are made in advance with formwork at a factory, etc., and then driven or buried in the foundation, and cast-in-place concrete piles that are made by drilling the foundation and directly pouring concrete into the hole. .

Among these concrete piles, especially prefabricated hollow concrete piles in which the center portion of the pile has a hollow portion along its axial direction, in order to form the hollow portion, a core has been generally used for a long time.

That is, a core made of a steel pipe or a plastic pipe is set at a central portion of a form, and concrete is poured outside the core, thereby producing a precast concrete pile having a hollow portion.

In addition, Japanese Patent Application Laid-Open No. Sho 62-174109 discloses a method of manufacturing precast concrete piles, that is, a flexible tubular core made of synthetic resin is placed in the center of the formwork, and hydraulic pressure is applied to the inside of the core. Finally, concrete is poured on the outside of the core. After the concrete is cured, the liquid pressure of the core is eliminated, so that the core shrinks and is pulled out, thereby making a precast concrete pile with a hollow part.

However, the manufacturing method of the prefabricated hollow concrete pile in the above-mentioned prior art has the following problems: it is very troublesome to keep the core in a concentric state with respect to the template; difficult.

For example, when the core is held by a steel bar embedded in a concrete pile, the core is fixed to the steel bar with a fixing wire. However, if a large amount of construction is performed at a distance of about 50 centimeters to fix the positions, a considerable amount of labor and time are required, thereby greatly reducing the pile-making efficiency.

In addition, if the core is not pulled out from the hollow part, but the core is buried in the state of the concrete pile, then one core is required for one pile, so the production cost is increased, and the economic benefit is great. Difference.

As shown in the above-mentioned known examples, although the method of using a tubular core can solve the problem of repeatedly using the core, it is very troublesome to keep the particularly soft core concentrically with respect to the template.

In addition, when using a horizontal formwork, compared with the known centrifugal molding method in which the formwork is rotated to form a hollow part, although the manufacturing equipment is simple, there are also problems in that the core is placed in the horizontal formwork, And after pouring concrete, since the core will either float or sink, it is very difficult to keep the core in a concentric shape in the horizontal formwork; moreover, the accuracy of the hollow part is low, even if the core shrinks It is also difficult to pull out.

Therefore, the present invention proposes a solution in order to solve the above problems, and its purpose is to provide a manufacturing method and manufacturing device for prefabricated hollow concrete piles, even when using Even in the case of a formwork arranged horizontally, it is possible to easily hold the core for forming the hollow part concentrically with respect to the formwork, and it is also possible to easily extract the core from the hollow part.

In order to achieve the above object, the solution adopted by the present invention is as follows: use an elastic tubular part that can expand and contract as a core, insert the tubular part into a horizontally arranged formwork, and press liquid into the tubular part to make the tubular part appear In the state of radial expansion, concrete is poured between the formwork and the tubular part. Due to the difference in specific gravity caused by the concrete, the tubular part is subjected to buoyancy and floats up. The tubular part is pressed by the holding device and kept in a concentric state relative to the formwork. After the concrete is poured, remove the holding device, and after the concrete solidifies, the hollow part is formed by the tubular part, and then the internal pressure of the tubular part is released, so that the tubular part shrinks radially, and the tubular part is pulled out from the hollow part.

According to the present invention constituted as above, the tubular member expands radially due to the pressurized liquid, and becomes a very strong core. In the expanded state, it floats up in the concrete and comes into contact with the holding device to be held. Therefore, even in the case of using a formwork installed horizontally, the concentric state of the tubular member with respect to the formwork in a horizontal shape can be easily and surely maintained without performing troublesome fixing work.

Moreover, in the hollow part formed concentrically with high precision, the tubular member radially contracts due to the release of the internal pressure, making the diameter smaller than the inner diameter of the hollow part, so that the tubular member can be pulled out from the hollow part very easily. .

According to the present invention as described above, compared with the centrifugal forming method in which the template is rotated, the manufacturing equipment is simple, and even in the case of using a horizontally arranged template, it is not necessary to carry out troublesome fixing. With a fixed operation, the tubular part can be kept in a concentric state with respect to the template simply and reliably, so the labor and man-hours for setting the tubular part can be greatly reduced, and the production efficiency of the prefabricated hollow concrete pile can be significantly improved.

Moreover, since the concentric hollow part and the shrinkable tubular part can be formed with high precision, the tubular part can be pulled out very easily, so the tubular part can be used repeatedly, and the production cost of the prefabricated hollow concrete pile can be greatly reduced. Significantly improve economic efficiency.

In addition, after the pouring of concrete is completed, the holding device is removed, so that a homogeneous prefabricated hollow concrete pile can be produced, which can greatly improve the tensile, compressive, and bending strength.

A brief description of the accompanying drawings is as follows:

Fig. 1 to Fig. 13 show an embodiment in which the present invention is applied to a manufacturing method and manufacturing apparatus of a prefabricated hollow concrete pile.

Fig. 1 is a perspective view showing a part of the produced pile in cross section.

Figure 2 is an oblique view of one end of the formwork in the closed mold state.

Fig. 3 is a sectional view pointed to by the arrow of line III-III in Fig. 2.

Fig. 4 is a sectional view pointed to by the arrow of line IV-IV in Fig. 2 .

Fig. 5 is a front view of one end of the template in the mold-opening state.

Fig. 6 is the same sectional view as Fig. 3 in the mold-opened state.

Fig. 7 is a front view of one end of the template in a modified example.

Figure 8 is a longitudinal section view of one end of the device when making the pile.

Fig. 9 is a longitudinal sectional view of a tubular member.

Fig. 10 and Fig. 11 are explanatory diagrams showing a method of manufacturing the tubular member.

Fig. 12 is an enlarged sectional view pointed to by the arrow of line Ⅻ-Ⅻ in Fig. 8.

Fig. 13 is a perspective view showing the rotation of the nut of the tensioning device for prestressed concrete reinforcement.

1... Concrete pile; 3... Hollow part; 10... Formwork; 11... Upper mold; 12... Lower mold; 14... Opening part; 40, 90... Pin hinge; 44, 45... Stop plate; 46... Stop device support Components; 48... Stop rod; 70... Pressurized water; 71... Concrete; 82... Hydraulic cylinder; 85a... Stop plate; 88... Stop piece; 91,92... Pin socket; 100... Tubular part; ... hose; 104 ... closing part; 120 ... retaining device; 121 ... retaining member; 123 ... installer; 124 ... hook; 126 ... joystick;

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

Fig. 1 - Fig. 13 show the embodiment of the manufacturing method and manufacturing device of the prefabricated hollow concrete pile.

First, as shown in Fig. 1, the concrete pile 1 made in this embodiment is a long-length member with a regular hexagonal section, and several nodes 2 protrude along the axial direction at a prescribed interval on its outer periphery. Moreover, a hollow part 3 with a circular cross-section is formed in the central part of the pile 1 along the axial direction. 4 is a number of (six in this example) prestressed concrete reinforcements embedded in the axial direction to apply prestress. Therefore, this pile 1 is a so-called hexagonal hollow prestressed concrete pile with joints.

Next, as shown in FIGS. 2 to 6, the above-mentioned formwork 10 for forming the concrete pile 1 is composed of an upper mold 11 and a lower mold 12 separated up and down along the central horizontal plane. Also, the template The length of 10 is about 7 times the length shown in Figure 2 (actually about 13 meters), and the other end not shown also has the same structure, and there are several structures shown in the figure between these two ends.

As shown in Fig. 3 and Fig. 6, the upper mold 11 has side plates 13 forming the outer peripheral surface of the pile 1, and an opening 14 for pouring concrete at the upper part. As shown in Fig. 2 and Fig. 4, a protruding portion 15 forming the section 2 of the pile 1 is provided on the side plate 13, and the upper part of this protruding portion 15 is also an opening portion 16. Also, a pair of U-shaped reinforcing members 17 are axially fixed on both outer sides of the protruding portion 15, and these reinforcing members 17 are connected by a connecting member 18 at the upper portion. As shown in FIGS. 2 and 5 , semicircular end panels 19 are fixed to the ends of the side panels 13 and the reinforcement members 17 . Therefore, the reinforcement part 17 , the coupling part 18 and the end panel 19 constitute the frame of the upper mold 11 .

On the other hand, as shown in Figures 3 and 4, the structure of the lower mold 12 is substantially the same as that of the upper mold 11, including a side plate 23 provided with a protruding portion 25, a pair of reinforcing members 27, and an end plate. 29 etc. form the frame of lower mold 12. In addition, the above-mentioned opening portions 14, 16 are not formed on the lower frame 12, but are completely closed. The lower part of the lower mold 12 is provided with several pairs of supporting feet 30, and the formwork 10 is arranged horizontally by these supporting feet 30. In addition, a buffer member 31 made of a rubber plate is provided on the leg 30 to absorb the vibration acting on the formwork 10 when the concrete is compacted.

In this way, as shown in FIGS. 2 to 6, a pin hinge 40 is provided on one side of the parting surface of the upper mold 11 and the lower mold 12 . This pin hinge 40 is made up of lugs 41, 42 and shaft pins 43. The lugs 41, 42 are respectively arranged on one side of the upper die 11 and the lower die 12 to protrude outward respectively, and the shaft pin 43 rotates these protrusions freely. Sheets 41, 42 are joined together. On the side of the end panels 19, 29 Outwardly protruding stopper plates 44, 45 are respectively provided, and these stopper plates 44, 45 constitute the first stopper means. On the lower die 12, a stopper support member 46 made of a pipe is vertically installed by means of a lug 47, and a stopper rod 48 that can be inserted is formed on this stopper support member 46 to become a second stopper. . In addition, pin hinges 40 are provided at four locations near both ends of the template 10 and two places between them, and stopper plates 44 , 45 and stopper support members 46 are provided near both ends of the template 10 .

Formwork 10 constituted by the above-mentioned method, at first under the mold-closed state as shown in Fig. Form a hexagonal column-shaped space for pouring concrete. In addition, the upper mold 11 and the lower mold 12 are firmly combined with a plurality of screws 52 at the outer edges 50, 51 of the protruding parts 15, 25 and the outer sides of the end panels 19, 29.

Next, as shown in Fig. 5 and Fig. 6, when the mold is opened, the screw 52 is loosened, and the suspension ring 33a of one side fixed on the reinforcing part 17 of the upper mold 11 is lifted by a hoist such as a crane or a hoist (without icon) raised. In addition, the other hanging ring 33b is used together with the hanging ring 33a when installing the entire template 10 after being transported by a lift. When lifting the upper mold 11, a pin hinge 40 is set on one side of the upper mold 11 and the lower mold 12, so that the upper mold 11 rotates in the direction shown by the arrow a with the pin hinge 40 as the center. Furthermore, when the upper die 11 is rotated to a position larger than 90° and approximately vertical, the end faces of the stopper plates 44 and 45 contact each other, and the upper die 11 stops rotating. And in the mold-opened state, the stopper rod 48 is vertically inserted into the stopper support portion 46 . Therefore, the side edge 50 of the upper die 11 is in contact with the stop bar 48, thereby preventing the upper die 11 from turning back to its original position.

Next, when the mold is closed, the stopper rod 48 is pulled out from the stopper support part 46, the elevator is lowered, and the upper mold 11 is rotated in the direction indicated by the arrow b. As shown in Figures 3 and 4, the side edges 50, 51 of the upper mold 11 and the lower mold 12 are tightly fastened together again.

As mentioned above, the upper mold 11 can rotate freely by the pin hinge 40, so when one template 10 is opened for operation, it is not necessary to keep the upper mold 11 in the state of being hoisted by a lifter. Therefore, by making one lifter move freely, it is possible to simultaneously perform mold opening and closing operations on several formworks 10 in parallel. In addition, the structure in which the upper mold 11 is rotated around the pin hinge 40 on one side requires approximately half the force compared to the structure in which the entire upper mold 11 is lifted, so a small lifter can be used. Mold closing is based on the rotation of the upper mold 11 centered on the pin hinge 40, so the positioning of the upper mold 11 and the lower mold 12 can be performed very simply without special operations. And because the upper die 11 is not separated from the lower die 12, there is no risk of injury to the worker due to the accidental movement of the upper die 11 during operation.

When patriarch 11 forwards to vertical state roughly, just make it stop by stop plate 44,45, so can make the space that patrix 11 takes is minimum when die opening, and a plurality of templates 10 can be set on the spot. At this time again, although the upper mold 11 has the danger of accidentally rotating to the mold closing direction, the stop bar 48 reliably prevents the upper mold 11 from turning back to its original position, so the safety is very high.

Next, in above-mentioned embodiment, mold opening and mold closing are to rotate upper mold 11 by lifter, but in the modified example shown in the 7th figure, but the driving device of upper mold 11 is provided with on template 10 itself. That is to say, the mounting plate 80 is fixed on the end panel 29 of the lower mold 12 , and the end of the hydraulic cylinder 82 is connected to the bracket 81 provided on the mounting plate 80 . and in The end portion of the piston rod 84 is connected to the bracket 83 provided on the end plate 19 of the upper mold 11 . In this modified example, outwardly protruding lugs 85 , 86 are provided on one side of the end panels 19 , 29 respectively. These lugs 85 , 86 are connected by a shaft pin 87 to form a pin hinge 90 . Furthermore, the front end portion of the protruding piece 85 is further protruded to become a stop piece 85 a, and a stopper 88 is fixed to the end plate 29 . Pin insertion holes 91 , 92 are respectively provided on the stop piece 85 a and the protruding piece 86 .

According to this modified example, when the piston rod 84 of the hydraulic cylinder 82 is stretched and contracted, the upper die 11 rotates relative to the lower die 12 in the directions indicated by arrows a and b with the pin hinge 90 as the center. Therefore, mold opening and closing can be performed on each formwork 10 itself without using a lift. When patrix 11 rotates a little more than 90 ° and is roughly vertical along the direction indicated by arrow a, stopper 85a just contacts with stopper 88, and stops its rotation (due to the effect of the 1st stopper). And stopper pin (not shown) is inserted in the pin insertion hole 91,92 that meets this state, prevents upper mold 11 from turning back original position along the direction indicated by arrow b (due to the effect of the 2nd stopper ). That is, in this modified example, since the rotation fulcrum and the rotation stopper of the upper mold 11 are both used, the structure becomes compact.

Next, as shown in Figures 8 and 9, the tubular member 100 used to form the hollow portion 3 of the concrete pile 1 is made of an elastic, expandable and tough synthetic resin hose 101. In this example, a cylindrical vinylon plain-woven canvas hose for agriculture (outer diameter D is 160 mm, cloth thickness t is 2 mm) is cut to a desired length (in this example, 10 m) , and apply an impermeable vinyl chloride coating on its surface and inside. Also, Vinylon is a trademark. Bind one end of the hose 101 with a rope, and tie it with an iron piece 103 Fastened so that the hose 101 is formed into a pouch with its closing portion 104 inside the pouch. Inside the other end of the hose 101, a sealing iron piece 105 is embedded and fastened with a hoop 105. A pipe 107 is welded on the above-mentioned sealing iron piece 105, and is connected with a flexible pipe 109 through a stop valve 108. And flexible pipe 109 is connected with the discharge port of pump 110, and the water inlet of this pump 110 just communicates with water tank 111. In addition, 112 is a motor for driving a pump, 113 is a pressure gauge, and 114 is a pressure reducing valve.

As mentioned above, the closed part 104 of the hose 101 is located inside the bag-like part, and as described later, when water is pressed into the tubular part 100, the water pressure P will act, so that the hose end at the closed part 104 will closely connected to each other. Therefore, water leakage from the closed portion 104 can be reliably prevented, ensuring complete water impermeability. In addition, the closed portion 104 is not exposed on the outside of the tubular member 100, so that the concrete does not wrap the closed portion 104. Therefore, there is no difficulty in pulling out the tubular part 100, and there is no need to cover the closing part 104 with a protective cap.

However, it is not easy to position the closing portion 104 inside the pouch portion on the above-mentioned large length of hose 101 . Therefore, when making it, as shown in Figure 10, one end of the hose 101 is closed from the outside, the other end of the hose 101 is turned outward, and then pulled in the direction of the arrow C, so that the hose 101 reversed. Another method, as shown in Figure 11, is to close one end of the hose 101 from the outside, and push the closed part 104 inside the hose 101 in the direction of the arrow d, so that the inside and outside of the hose 101 are reversed. change. After doing so, the hose 101 with the closing portion 104 inside the pocket can be produced very easily and quickly.

Next, as shown in FIG. 8 and FIG. 12, the holding device 120 for keeping the above-mentioned tubular member 100 and the template 10 in a concentric state is provided with a holding member 121, a mounting member 122 and an assembler 123. The holder 121 is arc-shaped corresponding to the outer circle of the tubular member 100 , and the mounting member 122 is connected to the upper part of the holder 121 , is roughly T-shaped, and is erected on the opening 14 of the upper mold 11 . Furthermore, the mounting part 122 is detachably mounted on the upper die 11 by means of a pair of assemblers 123 . The two assemblers 123 are respectively composed of a hook 124 that is engaged with the edge of the reinforcing part 17 of the upper mold 11, and a joystick that is supported on the mounting part 122 by a shaft 125 and can rotate freely in the directions indicated by arrows e and f. 126, and a tension spring 127 hung between the hook 124 and the joystick 126 constitutes. And when hanging the tension spring 127, it is required to be able to play the role of the toggle by the rotation of the joystick 126.

In addition, several holding devices 120 are arranged at a certain interval (50-80 cm in this example) in the axial direction on the upper part of the upper die 11 . Moreover, the position setting requirement of the holder 121 is as follows: when the tubular member 100 and the template 10 reach a concentric state, the holder is made to contact the outer circle of the tubular member 100 .

According to the holding device 120 mentioned above, when the joystick 126 is rotated inwardly in the direction indicated by the arrow e, the hook 124 is firmly engaged with the edge of the reinforcing member 17 through the tension spring 127 . Therefore, the holding device 120 can be accurately and quickly assembled on the predetermined position of the upper mold 11 . When the joystick 126 is rotated outwards according to the direction indicated by the arrow f, the engagement of the hook 124 and the edge of the reinforcing member 17 can be released. Thus, the holding device 120 can be released from the upper mold 11 quickly.

Moreover, as shown in FIGS. 2 and 8, a tensioning device 60 for tensioning the above-mentioned prestressed concrete reinforcement 4 is provided at the end of the formwork 10 . The same applies to the other end not shown in the figure. Tensioning device 60 is made of a circular plate 61, a screw shaft 62 inserted through this circular plate 61, a nut 63 engaged with screw shaft 62, and a hexagonal reinforcement mounting plate 64 fixed on the end of screw shaft 62. . The reinforcement assembly plate 64 is inserted into the template 10, and the screw shaft 62 passes through between the end panels 19, 29.

Next, with reference to Fig. 8 and Fig. 12, a method of manufacturing a concrete pile using the above-mentioned manufacturing apparatus will be described.

First, according to the state of mold opening above, a plurality of prestressed concrete steel bars 4 are installed on the steel bar assembly plate 64, and the hexagonal plate 65 used to form the end face of the pile 1 is pre-inserted on the prestressed concrete steel bars 4 and arranged on the lower Within the mold 12. According to the difference that the position of this hexagonal plate 65 is set, just can form the multiple pile 1 of long 4-10 meter with a template 10. Then, the tubular member 100 is inserted into the lower die 12 . After closing the mold according to the above method, use a tensioning machine (not shown) to tighten the disc 61 of the tensioning device 60, and apply a specified tension to the steel bar 4 through the nut 63, the screw shaft 62 and the steel bar assembly plate 64 . At this time, the tubular member 100 lies on the bottom of the lower mold 12 in a state supported on the prestressed concrete reinforcement 4 .

Next, the water in the water tank 111 is pressurized to, for example, 2 Kg/cm ² by the pump 110 , and injected into the above-mentioned tubular member 100 . After the pressurized water is injected into the tubular member 100, the tubular member 100 expands radially, and in this embodiment, the outer diameter is about 163 mm. Also at this stage, the tubular part 100 is still lying on the bottom of the lower mold 12 . In this way, the concrete 71 is poured between the formwork 10 and the tubular member 100 with the tubular member 100 in the state of increasing pipe diameter as a core.

Here, when the above-mentioned concrete 71 is poured, the formwork 10 is vibrated with a vibrator (not shown), and the tubular member 100 floats in the concrete 71 after the concrete 71 is vibrated. This is due to the difference between the specific gravity of the concrete 71 (approximately 1.80-2.45) and the specific gravity of the tubular member 100 and the pressurized water 70 (because most of it is water, it can be considered to be about 1), so that the tubular member 100 is affected by the concrete. The buoyancy of 71 is lifted.

The floating tubular member 100 contacts the holder 121 of the holding device 120 pre-installed on the upper mold 11, thereby pressing the floating tubular member 100 to maintain the concentric state with the template 10 correctly. And because the retainer 121 is formed into an arc shape corresponding to the outer circle of the tubular member 100, the tubular member 100 will not deviate laterally. In this state, pouring of concrete 71 is continued.

Next, after the pouring of the concrete 71 is completed, the holding device 120 is removed from the upper mold 11, and the holding member 121 is pulled out from the concrete. The space created by pulling out the holder is filled with concrete 71 . When the retainer 121 is pulled out, the tubular member 100 tends to float up, but the concrete 71 has a large flow resistance, so it can be prevented from floating up. Therefore, the tubular member 100 can maintain the concentric state with the formwork 10, and the concrete 71 is hardened in this state. After the concrete 71 has hardened, the central part of the pile 1 forms the required hollow part 3 thanks to the tubular part 100 .

Here, if the holding device 120 is not quickly removed from the upper mold 11 within an appropriate time after the concrete pouring is completed, not only internal defects will occur in the pile 1, but also the holding member 121 may not be pulled out. However, a large amount of labor and man-hours are required to remove many retaining devices 120 . However, according to the present embodiment, as described above, only turning the joystick 126 can simply complete the mounting and dismounting of the retaining device 120, therefore, a large number of retaining devices 120 can be quickly removed in a reasonable time with a small amount of labor. Furthermore, since the holding device 120 can be easily mounted on the upper die 11, preparations for the next process can also be carried out early.

Next step, when concrete 71 hardens, when reaching the strength (after about 4 hours) that can bear the degree of careful handling, open valve 108 and 114, make the pressure in tubular part 100 return to atmospheric pressure, so tubular part 100 relies on its own Elasticity produces radial contraction, and the outer diameter shrinks and returns to 160mm. Then, after the concrete 71 is fully hardened (after about 8 hours), mold opening is carried out as mentioned above, and the prestressed concrete reinforcement is cut off at the end face of the pile 1, and the pile 1 is taken out from the lower mold 12. Then, the tubular member 100 is pulled out from the hollow portion 3 in a direction indicated by an arrow g in FIG. 8 .

According to the above-mentioned manufacturing method, the tubular member 100 becomes a solid core due to the radial expansion of the injected pressurized water, so that the inner surface of the formed hollow part 3 is extremely smooth, and the size of the hollow part 3 is very precise. In this way, the tubular member 100 can be correctly kept concentric with the template 10 by the holding means 120, so the concentricity of the hollow portion 3 is extremely high. Therefore, the holding of the tubular member 100 by the retaining device 120 is a non-fixed holding that utilizes the difference in specific gravity to generate buoyancy, and the tubular member 100 shrinks radially by removing internal pressure. Thus, the tubular member 100 can be pulled out from the hollow portion 3 very easily.

In addition, when the prestressed concrete reinforcement bar 4 is sheared when taking out the above-mentioned pile 1, it is necessary to loosen the nut 63 of the pretensioning device 60. But prestressed concrete reinforcement 4 relies on tension Device 60 is subjected to strong tension, so it is not easy to make nut 63 turn round. Usually, it is troublesome to use a long wrench with a handle of 2 meters and two people to operate it.

Therefore, in this embodiment, as shown in FIG. 13, a disk-shaped member 66 for turning the nut 63 is prepared. At the center of this disc-shaped member 66, a cap hole 67 for fitting with a nut 63 is formed, and a toothed groove 68 is formed on the outer circumference thereof. And make the nut hole 67 and the nut 63 fit, the wire rope 69 is wound in the toothed groove, and the elevator used when utilizing the mold opening and closing the mold is used to pull up the wire rope 69, so that the disc-shaped member 66 is Turn in the direction indicated by the arrow h. Therefore, the nut 63 can be rotated and unscrewed very easily with a large rotational force by using the lifter for mold opening and closing without using a special tool or the like.

The embodiments of the present invention have been described above, but the present invention is not limited to the embodiments, and various effective modifications can be made according to the technical idea of the present invention.

For example, various materials can be used to manufacture the tubular member, as long as the material can elastically expand and contract in the radial direction under the action of internal pressure.

Also in this embodiment, water is used as the injected fluid, but as long as the specific gravity of the fluid is smaller than that of concrete, and the tubular member can be floated, any suitable fluid other than water (for example, air, oil, etc.) can also be used.

Claims (5)

1, a kind of preparation method of prefabricated hollow concrete stake comprises:

To have the tubular part that elasticity can breathing inserts in the horizontally disposed template;

Fluid is pressed in the above-mentioned tubular part, under the state that this tubular part is radially expanded, concrete is poured into a mould between above-mentioned template and tubular part;

Push down the buoyancy function that produces by the difference of concrete proportion and the above-mentioned tubular part that floats with holding device, also make this tubular part keep concentric simultaneously with respect to above-mentioned template;

After finishing concrete cast, lay down above-mentioned holding device;

Concrete curing, and after forming hollow parts by above-mentioned tubular part, remove the interior pressure of above-mentioned tubular part, make this tubular part generation radial contraction after, this tubular part is extracted from above-mentioned hollow parts.

2, a kind of producing device of prefabricated hollow concrete stake has:

Tubular part, having elasticity can breathing, can insert in the horizontally disposed template, by being pressed into fluid to its inside it is radially expanded, and pressure then makes its radial contraction in removing;

Holding device is used for cast concrete between above-mentioned template and above-mentioned tubular part, when producing buoyancy because of the difference of concrete proportion, pushes down the tubular part because of floated by buoyancy, and makes this tubular part keep concentric with respect to above-mentioned template.

3, the producing device of prefabricated hollow concrete stake according to claim 2 is characterized in that:

Above-mentioned holding device has, with the corresponding circular-arc keeper of above-mentioned tubular part cylindrical, be erected at opening part above the above-mentioned template installed part, can make above-mentioned installed part on template, load and unload freely assembler;

Above-mentioned assembler system by and above-mentioned template hang the hook that closes, rotate freely that the earth's axis is bearing in the control stick on the above-mentioned assembly, the tension spring of hanging up between above-mentioned hook and above-mentioned control stick constitutes.

4, the producing device of prefabricated hollow concrete stake according to claim 2, it is characterized in that: above-mentioned template is made of upper die and lower die, side at the die joint of these upper die and lower die is provided with the pin hinge, cuts with scissors patrix constituted with respect to counterdie by this pin and rotates freely.

5, the producing device of prefabricated hollow concrete stake according to claim 4, it is characterized in that: be provided with first retainer and second retainer, first retainer can make patrix stop operating going under the die opening state of upright position, and second retainer is used to prevent that the patrix of die sinking from rotating to the mold closing direction.

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