JP2622487B2 - Inner formwork for manufacturing precast concrete column members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner mold for manufacturing a precast concrete column member which is installed at an inner peripheral side of a precast concrete column member having a hollow cross section and is used repeatedly.

[0002]

2. Description of the Related Art A method of manufacturing a precast concrete column member to have a hollow cross-sectional shape for the purpose of increasing the transportation efficiency by reducing the weight of the member and reducing the load on the lifting equipment is known. A method of expanding the rubber film that becomes the inner mold using air pressure, shrinking it after hardening concrete, and removing the mold, the outer mold by centrifugal force due to rotation of the outer mold around the axis without using the inner mold There is a method of attaching concrete to the inner periphery of the frame, and a method of removing the inner mold using a dedicated demolding device.However, the cost of materials and equipment is high, which tends to increase manufacturing costs. is there.

[0003] The present invention has been made by paying attention to a conventional method of forming a hollow portion in a precast concrete column member, and aims to propose an inner mold having a structure that can be installed and removed by a simple method. is there.

[0004]

According to the present invention, the inner mold forming the hollow portion of the precast concrete column member is divided into two to facilitate removal of the mold after hardening of the concrete.
In particular, a cylinder having a circular or similar cross-sectional shape is divided into two parts vertically in a horizontal plane including its central axis, thereby minimizing the stress applied to the dividing position due to the lateral pressure of the poured concrete. This facilitates holding against relative deformation between the two molds.

The two steel plate forms forming the inner form are superposed on each other at the end of the cross section at an intermediate position in the height direction, and when assembled in a circular shape, a precast concrete column having a hollow cross section is formed. It is installed at a position on the inner peripheral side of the member.

[0006] The lateral pressure on the inner mold due to the concrete before hardening is distributed in a trapezoidal shape, and the bending moment generated in the circular inner mold is distributed at the middle position in the height direction as an inflection point. The stress at the dividing position is minimized, the relative deformation between the upper and lower steel plate forms is small, and both forms can be held against the lateral pressure by simple means.

A drawing member for reducing the cross-section is connected to one of the two steel plates of the inner mold, and the other of the two steel plates is contracted with the drawing member after a certain amount of contraction of the steel plate by the drawing member. By connecting the engaged member that moves toward the center on the cross section, it is possible to remove the mold by a simple method and restore it to the shape at the time of placing concrete, and the cost required for forming the hollow part of the precast concrete column member To reduce.

[0008] The pulling member is connected to the inner periphery of both ends on the cross section of one of the steel sheet forms, and this steel sheet form is contracted by the drawing members being drawn toward the center sides of both ends, and is removed from the concrete. You.

The engaged member is fixed to the inner periphery of both ends on the cross section of the other steel sheet form, and after a certain amount of drawing of one steel sheet form by the drawing member, the engaged member is indirectly attached to the steel sheet form. It is engaged with the outer peripheral side on the cross section, and is pulled toward the center together with the pulling member. The steel plate form on the other side is formed by contracting the steel plate form on the one side until the distance between both ends thereof becomes a certain length, and then the engaged member engages with the pulling member, whereby the steel plate form on the one side is formed. It shrinks with it and is released.

[0010] Both steel sheet forms are restored to their original shapes by releasing the pulling force applied to the pulling member introduced to shrink the both.

The removal of the inner mold is performed simultaneously by the contraction of one of the two divided steel plate forms, thereby simplifying the mechanism required for removal and reducing the manufacturing cost of the precast concrete column member. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing one embodiment.

As shown in FIG. 5, the inner mold 1 of the present invention comprises two steel plate molds 2 and 3 having a semicircular shape or a sectional shape close to the semicircular shape. It is installed at the inner peripheral side of the precast concrete column member having the shape, and after the concrete 9 has hardened, it is removed from the mold as shown in FIG. 6 and is used repeatedly.

The inner mold 1 has a shape of a cylinder having a circular shape or a sectional shape close to that of a circular shape, and is vertically divided into two parts by a horizontal plane including the center axis. They are superimposed on each other at the end of the intermediate position in the height direction, and assembled in a circular shape.

A pulling member 4 for pulling both ends toward the center as shown in FIG. 1 is connected to the inner periphery of both ends of the cross section of one steel plate form, in this embodiment, the lower steel plate form 2, After a certain amount of the one steel plate form 2 is drawn by the pulling member 4 to the inner periphery of both ends on the cross section of the other steel plate form 3, the other steel plate form 2 is indirectly moved to the outer peripheral side on the cross section. The engaged member 5 that is engaged and drawn toward the center together with the pulling member 4 is fixed.

FIG. 3 is a cross sectional view of FIG.
In order to transmit the tensile force of the pulling member 4 in the axial direction of the inner mold 1 over the entire length thereof, since the pulling member 4 is disposed outside the end mold 8 of the precast concrete column member in the operation as shown in FIG. Further, stiffening members 6 and 7 connected to the pulling member 4 are joined to both ends on the cross section of each steel plate form 2 and 3.

As will be described later, when the inner mold 1 is removed from the mold, FIG.
As shown in FIG. 1, after one steel plate form 2 contracts, the other steel plate form 3 contracts in a manner surrounding the one steel plate form 2, so that the stiffening member 6 is made of a steel plate as shown in FIG. Formwork 2
Project from both ends on the cross section of the steel sheet form 3 toward the other steel sheet form 3, and both ends of the steel form 3 project from the stiffening member 7 toward the steel form 2 side.

The pulling member 4 is, for example, as shown in FIG.
At least one end is threaded, and a tension member 41 erected between the stiffening members 6 and 6 is screwed into the threaded portion, and is screwed into the center of the cross section of the steel sheet form 2. And a nut 42 for releasing the stiffening members 6 and 6 toward the center.

In the embodiment, as described above, the pulling member 4 is installed outside the end mold 8 as shown in FIG. The connection plate 43 projecting outward from the axial end face of the stiffening member 6 is welded to the center of the stiffening member 6 in accordance with the arrangement at the position where the stiffening member 6 does not interfere. Although it is erected, the tension member 41 may be penetrated directly through the stiffening member 6 on the mechanism. Further, in the embodiment, the tensile force is applied to the tensile member 41 by the operation of the removing nut 42, and the stiffening members 6,
The pulling member 4 has a function similar to that of a turnbuckle in which both ends thereof approach each other due to a tensile force. Therefore, the structure is not limited to the embodiment. In the case of the embodiment, the tension member 41 penetrates the connection plate 43, and a releasing nut 42 is screwed to the outside on the cross section,
The unmating nut 42 is engaged with the connecting plate 43 from the outside on the cross section, so that the nut 42 is screwed into the center, so that the connecting plate 43
By moving 43, the distance between the stiffening members 6 and 6 is shortened, and the steel plate form 2 is contracted to release from the concrete 9. The pulling members 4 are installed at both ends in the axial direction for transmitting the force to the steel plate form 2.

In the embodiment, as shown in FIG. 2, the separator 11 which is engaged with the stiffening member 6 to the center side to keep the distance between the stiffening members 6 and 6 constant is provided on both the stiffening members of the steel plate form 2. By extending between the 6, 6, the spread of the steel sheet form 2 is prevented, and the dimensional accuracy of the inner form 1 is increased.

The engaged member 5 is engaged with an engaging member 10 projecting from the end of the stiffening member 6 of the steel plate form 2 on the end side of the precast concrete column member as shown in FIG. As shown in FIG. 2, the tension members 41 are directly engaged with the stiffening members 6 from the center side to the outer periphery side at predetermined intervals in the axial direction of the tension members 41. The engaged member 5 is a part of the steel plate form 2 by the pulling member 4.
By engaging the engaging member 10 and the stiffening member 6 after a certain amount of contraction corresponding to the above-mentioned interval, the tensile force of the tension member 41 is transmitted to the stiffening member 7 of the steel plate form 3, , 7 are drawn toward the center.

As shown in FIGS. 1 and 5, the concrete 9 has two steel plate forms 2 and 3 overlapped with each other at both ends in cross section, and a spacer 12 between the stiffening member 6 and the stiffening member 7 The molds 2 and 3 are cast in a state where the mutual positions are maintained. When the concrete 9 is poured, pressure acts from around the inner form 1, but pressure distributed in a trapezoidal shape acts from both sides as shown in FIG. 7, and the bending moment is shown in FIG. As shown in the figure, since the middle part in the height direction is distributed as an inflection point, the bending moment in the vicinity of the overlapping position of the steel plate forms 2 and 3 is small by dividing the inner form 1 into two vertically, The influence of the stress acting on the end positions of the steel plate forms 2 and 3 and the accompanying deformation is small, and there is no need for stiffening at the ends. Before hardening, the inner mold 1 resists the buoyancy acting on the inner mold 1 while the concrete 9 is being fluidized, by being fixed to the worktable supporting the end mold 8.

The removal of the inner mold 1 is performed by screwing the removal nut 42 into the center after the concrete 9 is hardened. When the mold release nut 42 is moved, the steel plate form 2 is first contracted, and when the distance between the engaged member 5 and the engaging member 10 or the distance between the engaged member 5 and the stiffening member 6 is contracted, The engaging member 10 and the stiffening member 6 are engaged with the joining member 5,
By transmitting the tensile force of the tensile member 41, the steel plate form 3 contracts while circumscribing the steel plate form 2 as shown in FIG. 6, and the two steel plate forms 2 and 3 are released.

After the mold is released, the shape of the steel plate forms 2 and 3 is restored by loosening the release nut 42. The position of the upper steel plate form 3 is restored as shown in FIGS. A spacer 12 is inserted between the stiffening member 6 and the stiffening member 7,
By pushing it upward.

Inner form 1 after both steel sheet forms 2 and 3 are separated
Is assembled by sandwiching the stiffening members 6 and 6 at both ends of the upper steel plate form 3 and placing the upper steel plate form 3 on the lower steel plate form 2 via the spacer 12.

[0026]

As described above, the present invention provides an inner mold for forming a hollow portion of a precast concrete column member.
The cylinder is divided into two parts, a cylinder having a circular shape or a sectional shape close to it, which is divided into two parts up and down on the horizontal plane including the center axis. It is possible to minimize the stress acting on the dividing position due to the lateral pressure, and to easily maintain the relative deformation between the two molds due to the division.

Also, a pulling member for reducing the cross section is connected to one of the two steel plate forms superimposed in a circular shape, and the other with the drawing member after a certain amount of contraction of one of the forms by the pulling member. The engaged member that moves toward the center on the cross section is connected, and the pulling member pulls the steel plate form at both ends to remove it from concrete and restore the original shape by releasing the pulling force to the pulling member Therefore, the mold can be easily removed and converted, and the cost required for forming the hollow portion of the precast concrete column member can be reduced.

In addition, the mechanism for removing the mold is simple, and the assembly can be performed simply by placing the upper steel form on the lower steel form, so that it is easy to manufacture, assemble and disassemble, and easy to inspect and repair. Can be done.

[Brief description of the drawings]

FIG. 1 is an elevational view showing an end of an inner mold.

FIG. 2 is a cross-sectional view showing an intermediate portion of the inner mold.

FIG. 3 is a cross-sectional view of FIG.

FIG. 4 is a cross-sectional view of FIG.

FIG. 5 is a schematic diagram showing an assembled state of an inner mold.

FIG. 6 is a schematic diagram showing a state when the inner mold is removed from the mold.

FIG. 7 is a diagram showing a pressure distribution on a side surface of the inner mold.

FIG. 8 is a bending moment diagram showing a bending moment generated in an inner mold.

[Description of Signs] 1 ... Inner form, 2 ... Steel plate form, 3 ... Steel plate form, 4 ...
… Pulling member, 41… Tensile material, 42… Nut for removal, 43
... connecting plate, 5 ... engaged member, 6 ... stiffening member, 7 ... stiffening member, 8 ... end formwork, 9 ... concrete, 10 ... engaging member, 11 ... Separator, 12 spacer.

Claims (2)

(57) [Claims] 1. An inner mold which is installed at a position on the inner peripheral side of a precast concrete column member having a hollow cross section in a state assembled in a circular shape, is demolded after hardening of concrete, and is used repeatedly. , Or a cylinder having a cross-sectional shape close to it,
An inner mold for manufacturing a precast concrete column member, comprising two steel plate molds having a divided shape, and being overlapped with each other at an end portion at an intermediate position in a height direction in cross section. 2. A pulling member that pulls both ends to the center side is connected to the inner periphery of both ends on the cross section of one steel sheet formwork,
After a certain amount of drawing of the one steel sheet form by the pulling member on the inner periphery of both ends on the cross section of the other steel sheet form, the steel sheet form is indirectly engaged with the outer peripheral side on the cross section, The engaged member drawn toward the center together with the pulling member is fixed, and is contracted and removed when the concrete is hardened and pulled by the pulling member. Inner formwork for manufacturing precast concrete column members.