JPH10100130A - Demolding method of nodular pile mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a demolding method of a nodular pile mold capable of efficiently and easily performing demolding, even under such a state that demolding force is increased accompanied by the release of the impartment of tensile force to a PC steel rod. SOLUTION: A pile 1 fitted with a prestressed high strength concrete node having a plurality of axially extending PC steel rods embedded therein is molded by a form 3 having a two-split cylindrical structure consisting of semicylindrical up and down form parts 31, 32, and the respective form parts 31, 32 are relatively separated from the pile 1 in the direction crossing the axial direction thereof at a right angle. At this time, the separation operation of both end side parts 311 , 321 in the axial direction is started so as to be delayed from the separation operation of central parts 312 , 322 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a prestressed high-strength concrete knotted pile in which a plurality of PC steel rods extending in the axial direction are buried under moderate tension.
After forming with a half-cylindrical formwork consisting of a semi-cylindrical upper and lower formwork part, knotted pile forming to relatively separate each formwork part from the pile in a direction perpendicular to the axial direction. The present invention relates to a mold release method.

[0002]

2. Description of the Related Art As shown in FIG. 8, a prestressed high-strength concrete knotted pile 1 is a cylindrical member having a ring-shaped node 1a bulging out in a trapezoidal shape on an outer peripheral portion thereof, and extending in an axial direction. , Which are buried in a state where an appropriate tension (tensile force) is applied thereto. In addition, PC steel rod 1
An end fitting (commonly called "Hakama") 1c in the shape of an annular plate to which the ends of "b" are fixed is crimped.

[0003] Such a knotted pile 1 is generally formed by a centrifugal molding method, and a molding die 2 used for this is a mold frame 3 having a split cylindrical structure as shown in Figs.
And a tension applying member 4 for applying an appropriate tension to the plurality of PC steel bars 1b arranged in the formwork 3. In addition,
In the following description, front and rear mean left and right in FIG. 4, and left and right mean left and right in FIG. 6, respectively.

As shown in FIGS. 4 to 6, the mold 3 is formed on its outer periphery with a plurality of node forming portions 3a having an annular and trapezoidal cross section at predetermined intervals in the front-rear direction along the axial direction. And a plurality of rolling wheels 3c (only one shown) having a slightly larger diameter than the joint forming portion 3a are fixed to a portion where the joint forming portion 3a does not exist, and are fixed to the front end (and the rear end). It has a cylindrical structure formed by protruding a disk-shaped end flange 3b,
The upper and lower frame portions 3 each having a semi-cylindrical shape on the diameter plane XX, including the joint forming portions 3a, the end flanges 3b, and the rolling wheels 3c.
It is divided into 1 and 32. The upper mold portion 31 and the lower mold portion 32 have rectangular band-shaped fastening flanges 31a, 31a and 32a protruding from left and right ends, which are both ends in the circumferential direction.
By affixing 32a with a fixing tool (not shown) such as a bolt and a nut in a state of being abutted on the dividing plane XX, the cylindrical form 3 can be assembled.

As shown in FIGS. 4 and 5, the tension applying member 4 has a disk-shaped support member 6 which can be slidably inserted in the mold frame 3 in the axial direction, and a center of the support member 6. A tension bolt 7 protruding from the portion, a disc-shaped supporting body 8 having a through hole formed in the center for inserting the tension bolt 7, and a tension nut 9 screwed to the tension bolt 7. It is provided. The tension applying members 4 are arranged at the front and rear ends of the mold frame 3, but since they are symmetrical in the axial direction, one of them is arranged at the rear end. Is omitted.

[0006] The pile 1 is manufactured by the centrifugal molding method using the molding die 2 having such a configuration as follows.

That is, a plurality of PC steel bars 1b..., A pair of end fittings (only one is shown) 1c
After being integrated into a cylindrical palanquin shape by being fixed to the lower frame member 32, the end portion of the PC steel rod 1b is attached to the supporting body 6 by a fixing nut 1d. Then, a predetermined amount of concrete 1 'is poured into the lower mold part 32, and then the upper and lower mold parts 31, 32 are fastened to form the mold 3'.
(See FIG. 5).

Next, after tightening one tension nut 9 to apply tension (tensile force) to the PC steel rods 1b, the mold 3 is rotated by a centrifugal molding machine, and the concrete 1 'is rotated. By applying centrifugal force to the concrete, the concrete 1 'is formed into a knotted cylindrical shape, and further heated and cured with steam to promote solidification, thereby obtaining the pile 1 (see FIG. 4).

After the curing is completed, the tension nut 9 is loosened to release the tension application to the PC steel bars 1b, and the upper and lower mold sections 3 are fastened by the fastening flanges 31a and 32a.
After releasing the fastening of the respective mold sections 31 and 32,
Are sequentially demolded, but the conventional demolding method (hereinafter “conventional method”)
In general, the respective mold sections 31 and 32 are relatively detached from the pile 1 in a direction orthogonal to the axial direction by the following procedure.

That is, first, the upper mold frame portion 31 is
As shown in the figure, a plurality of hanging members 12 provided on the hanging beam 11 are provided.
(FIG. A), the lifting beam 11 is lifted, and the entire upper and lower portions of the upper frame portion 31 in the front-rear direction are simultaneously lifted by the same amount, that is, horizontally. It is relatively detached from the frame portion 31 (FIG. B). Next, after removing the tension applying members 4 from the pile 1 and the lower mold section 32, the lower mold section 32 is piled by an appropriate tilting device (not shown) as shown in FIG. 1 is tilted by a predetermined amount around the axis (FIGS. A and B), that is, all portions of the lower mold section 32 in the front-rear direction are simultaneously tilted by the same amount, and the pile 1 is tilted.
Are rolled out of the lower mold portion 32 to relatively separate from the pile 1 (FIG. C).

[0011]

However, according to such a conventional method, the upper and lower mold sections 3 are not provided for the following reasons.
Demolding of 1,32 was extremely difficult.

That is, since the tension is applied to the PC steel bars 1b by tightening the tension nuts 9, the supporting members 8 are abutted against the end flanges 3b. The reaction force caused by the application of the tension is received by the mold 3 via the tension applying member 4. That is, the mold 3 receives the compressive force in the axial direction due to the reaction force. For this reason, by applying tension to the PC steel bars 1b, in the axial direction, the PC steel bars 1b
b are elongated (elastically deformed), while receiving the reaction force, the mold 3 is contracted (elastically deformed) (solid line in FIG. 4, chain line in FIG. 5).

Therefore, after curing, the tension nut 9
Is released to release the application of the tension to the PC steel bars 1b..., As shown by the chain line in FIG. On the other hand, the pile 1 is subjected to the compressive force of the PC steel rods 1b, etc., which the form 3 bears, and therefore, as shown by the two-dot chain line in FIG. Will be reduced. Therefore,
Apparently, each joint 1a of the pile 1 and each joint forming portion 3a of the mold frame 3 are relatively displaced in the axial direction. That is, as shown by a dashed line in FIG.
a is displaced by a predetermined amount L ₁ in the end flange direction A with the elongation of the mold 3, and as shown by a two-dot chain line in FIG. results in the opposite direction (mold 3 of the central portion direction) a predetermined amount L ₂ is displaced in the B (two-dot chain line), both 1a, is between 3a, the side surface 1a ₁ of the end flange side in section 1a and a node forming and side 3a ₁ of the end-flange of the section 3a is possible to increase the relative displacement in a direction (axial direction) away.

By the way, the above-described joint 1a and the joint forming part 3a
Relative displacement in the axial direction with
And the displacement L (= L₁+ L_Two) To the "section
Relative displacement ”) is the axis of the pile 1 or form 3
The center in the direction (hereinafter referred to as “deformation reference portion”) YY
As a result, it occurs symmetrically. That is, as shown in FIG.
And the front end side of the deformation reference portion YY (left side in the figure)
Then, each node 1a is displaced backward and each node forming portion 3a
Is displaced forward, and conversely, on the rear end side (the same
(Right side in the figure), when each node 1a is displaced forward,
Then, each joint forming portion 3a is displaced rearward. And each knot molding
Displacement L of part 3a₁And the displacement L of each node 1a _TwoIn other words, clause
The partial relative displacement amount L is smaller as approaching the deformation reference portion YY.
And becomes larger as the distance from the deformation reference portion YY increases.
In the following, both side surfaces of the node 1a and the node forming portion 3a
Of the end flange side (from the deformation reference portion YY
On the front end side, it is the front side, from the deformation reference portion Y-Y
The rear side is the rear side on the rear end side) 1a₁, 3a₁To "No.
One side ", the other side, that is, the deformation reference portion YY side
Side 1a of_Two, 3a_TwoIs referred to as a “second aspect”.

However, actually, the node 1a and the node forming portion 3a
Are engaged and the relative displacement of the two 1a, 3a is prevented, and thus the node portion relative displacement is replaced as an increase in the engaging force between the node 1a and the node forming portion 3a in the axial direction. will be mutual pressing force at the contact portion C between the second side surface 3a ₂ of the second side surface 1a ₂ and a node forming part 3a sections 1a becomes extremely large. By the way, since the node portion relative displacement amount L becomes smaller as approaching the deformation reference portion YY as described above, the mutual pressing force at the contact portion C becomes the smallest at the central portion of the mold 3.

As shown in FIG. 6A, the mold 3 is divided into two semi-cylindrical upper and lower mold sections 31 and 32, and the upper mold section 31 and the lower mold section 32 are divided into two sections. Left and right end 3
1b, 31b and 32b, 32b are the diameter surfaces X of the pile 1
Since it is located on −X, the force required to remove the mold portions 31 and 32 (hereinafter referred to as “demolding force”) is the largest in the initial stage of demolding. That is, for example, the upper mold section 3
1, as shown in FIG.
When the left and right ends 31b, 31b are slightly displaced from the diameter plane XX, that is, when the intersection angle θ between the ends 31b, 31b with respect to the pile center is less than 180 °, both ends 31b
Even when the piles 1b and 31b are in strong contact with each other, the circular peripheral surface of the pile 1 functions as a draft, so that the pressing force of the ends 31b and 31b against the pile 1 can be released. A component force (hereinafter referred to as “demolding assisting force”) in the direction in which the demolding is promoted is generated, thereby reducing the demolding force and facilitating the subsequent demolding action. However, at the initial stage of demolding, as shown in FIG. Is the diameter surface X
Since it is located on -X, the circular peripheral surface of the pile 1 does not function as a draft. Therefore, both ends 31b, 3
Although the pressing force of the pile 1b against the pile 1 generates a demolding inhibiting force (frictional force), the demolding promoting force does not generate this force, and the demolding force required at the initial stage of demolding (that is, both ends 31b, 31b). Is an acting force in the demolding direction necessary for displacing from the diametric plane XX, which will be hereinafter referred to as an “initial demolding force”. This is the same when the lower mold part 32 is removed from the mold. If the mold 3 is divided into three or more sections, the intersection angle θ at both ends in the circumferential direction of each mold section is less than 180 ° (for example, 120 ° in three sections). The peripheral surface functions as a draft, and the initial demolding force is also reduced. However, dividing the mold frame 3 into three or more parts is not practical because it causes structural and operational problems (problems such as reduced mold strength and complicated operations).

As described above, the mutual pressing force at the contact portion (the contact portion between the second side surfaces 1a ₂ and 3a ₂ ) C between the node 1a of the pile 1 and the node forming portion 3a of the frame portions 31 and 32 is a tensile force. The formwork part 3
The initial demolding force (hereinafter, referred to as “node initial demolding force”) required for each of the knot forming portions 3a is equal to the knot forming portion 3a.
The initial demolding force required for each part other than the above (hereinafter referred to as “non-node partial initial demolding force”) is extremely large.

Therefore, the entire formwork portions 31, 32 which are extremely long and have a large number of knot forming portions requiring a larger initial demolding force (node initial demolding force) are required for this. The initial demolding force (hereinafter, referred to as “all initial demolding force”) becomes extremely large, which means that the pile 1 and the pile 1 can be removed from the lower mold section 32 using only the weight of the pile 1 alone. Demolding of the upper mold frame portion 31 using the weight of the lower mold portion 32 is also a cause of making demolding difficult.

The present invention has been made in view of the above points, and even if the initial demolding force of the node part is increased with the release of the tension application to the PC steel rod, the demolding is performed. It is an object of the present invention to provide a method for removing a knitted pile forming die capable of efficiently and easily performing the knitting.

[0020]

SUMMARY OF THE INVENTION The present invention provides a prestressed high-strength concrete knotted pile comprising a plurality of axially extending PC steel rods embedded therein. In the demolding method in which each mold portion is relatively detached from the pile in a direction perpendicular to the axial direction after being molded by the mold having the split cylindrical structure, in order to achieve the above object, particularly, It is proposed that the mold section be released by starting the release operation of both end portions in the axial direction later than the release operation of the central portion.

When the tension application to the PC steel rod is released,
Due to the elongation of the mold and the reduction of the pile, the mutual pressing force between the knot forming portion and the knot increases. However, the pressing force on the node forming portion by the node is not uniform in the axial direction of the mold, but is small at the central portion and large at both end portions as described above. That is, although the non-node initial release force is equal in the axial direction of the mold, the node initial release force is proportional to the pressing force, and therefore is small at the center portion and large at both end portions. Become. Accordingly, the operation of detaching the center portion of the mold portion from the pile can be performed more easily than the case of detaching the both end portions of the mold portion from the pile.

When the detaching operation of the central portion is started prior to the detaching operation of the both end portions, the form portion is moved in the axial direction from the both end portions to the central portion along with the former operation. It bends and deforms into a form as if it were drawn. That is, each knot forming portion is displaced in the direction approaching the deformation reference portion which is the axial center portion of the pile 1 or the mold frame 3 due to such bending deformation. As a result, the knots are formed at both end portions. The pressing force between the joint forming portion and the joint forming portion is greatly reduced.

Therefore, after the separation operation of the central portion is started, the initial demolding force of the knot portion at both end portions is greatly reduced, and the separation operation of the both end portions from the pile can be easily performed. Can do it.

As described above, according to the demolding method of the present invention,
Demolding of the mold portion can be performed extremely easily as compared with a case where the entire mold portion is separated from the pile at a stroke as in the conventional method.

[0025]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be specifically described with reference to FIGS.

In this embodiment, after the prestressed high-strength concrete knotted pile 1 shown in FIG. 8 is formed by the forming die 2 shown in FIGS. 4 to 6, a knot portion relative displacement as shown in FIG. 7 is generated. The present invention relates to an example in which the present invention is applied to a demolding method in which each of the formwork portions 31 and 32 is relatively detached from the pile 1 in a direction orthogonal to the axial direction thereof.

In the demolding method of this embodiment, first, as shown in FIG.
1 lifts off the pile 1 and the lower mold section 32 upward.

That is, the plurality of hanging members 13 provided on the hanging beam 11 are engaged with and connected to the upper mold frame portion 31 (FIG. 1A). The length of each of the hanging members 13, 14 is different, and the length H _{1 of the} hanging members (hereinafter, referred to as “first hanging members”) 13 connected to both end portions 31 ₁ , 31 ₁ of the upper mold frame portion 31. is hanger to be connected to the center portion 31 ₂ (hereinafter, "second
Suspender "hereinafter) 14 ... it is predetermined amount set longer than the length of H _2.

Next, the suspension beam 11 is lifted, and the upper frame portion 31 is lifted. In this case, since the length H ₁ of the first suspender 13 is set longer than the length H ₂ of the second suspension link 14 as described above, causes the lifting beam 11 is raised a predetermined amount, first second suspender Upper frame part 31 connected to 14 ...
Only the central portion 31 ₂ will be lifted, the upper mold half 31 is resiliently deformed convexly upward as a whole (Fig. (B)).

By the way, when the tension applying to the PC steel bars 1b by the tension applying member 4 is released before the mold is released, the joint forming section is formed by the extension of the mold frame 3 and the reduction of the pile 1 as shown in FIG. Second side surfaces 1a ₂ and 3a _{2 of} 3a and node 1a
The mutual pressing force at the contact portion C increases. However, the pressing force of the sections forming part 3a by section 1a is not uniform in the axial direction of the upper mold half 3, as mentioned at the outset, smaller in the central portion 31 _2, both end side portions 31 _1, 31
_{Great at 1} . That is, Hifushi partial initial demolding force is uniform in the axial direction of the upper mold half 3, node portion early demolding force, since in proportion to the pressing force, small in the central portion 31 _2, Both end portions 31 ₁ , 31
Greater at ₁ . Therefore, only the central portion 31 ₂ be detached operation from the pile 1 as described above,
The operation can be easily performed as compared with the case where the end portions 31 ₁ and 31 ₁ are separated from the pile 1.

Then, the central portion 31_TwoTo both ends 31
₁, 31₁By lifting it up before
When the minute 31 is bent and deformed into the above-mentioned convex shape, the pile
1 in the axial direction, both end portions of the upper mold portion 31
31₁, 31₁Is the central part 31_TwoAttracted towards
Will be. That is, both end portions 31₁, 31 ₁
In FIG. 3, as shown by a chain line in FIG.
Due to the warping deformation, the pile 1 or the mold 3 is axially centered.
Displaced in the direction approaching the deformation reference portion Y-Y
And the second side surface 3a of the node forming portion 3a_TwoIs the second side of section 1a
1a_TwoWill be displaced in the direction away from. That
As a result, the second side surface 1a_Two, 3a_TwoAt the contact part C
The pressing force is greatly reduced, and both end portions 31
₁, 31₁The initial demolding force at the node is extremely small
You.

In such a state, the suspension beam 11
Is further raised, the both end portions 31 ₁ , 31 _{1 of} the upper mold frame portion 31 connected to the first hanging members 13... Are lifted, and the upper mold frame portion 31 as a whole projects upward. In the deformed form, it is detached upward from the pile 1 and the lower mold section 32, and the removal of the upper mold section 31 is completed (FIG. 3C).

At this time, the initial demolding force of the knot portion at both end portions 31 ₁ , 31 ₁ is, as described above, the central portion 3 1.
Since it was reduced by 1 ₂ is lifted prior to both end portion 31 _1, 31 _1, central portion 31
The detachment operation of the both end portions 31 ₁ , 31 _{1 from} the pile 1 which is performed subsequently to ₂ is also easily performed.

Therefore, the entire upper mold section is removed from the pile.
Compared to the conventional method, which allows the user to leave at once,
Therefore, it is very easy to remove the upper mold portion 31 from the mold.
it can. In addition, the bending degree of the lifting posture of the upper mold frame portion 31.
Is the length H of the first hanging member 13₁And the length H of the second hanging member 14_Two
Difference (H₁-H_Two) Can be determined arbitrarily
And both ends 31₁, 31₁Node initial demolding in
Force 31₁, 31 ₁Easy removal from pile 1
And the upper mold section
31 under the condition that it does not deform beyond its elastic limit.
Can be set appropriately.

When the removal of the upper mold portion 31 is completed, the tension applying members 4 are removed from the pile 1 and the lower mold portion 32, and the lower mold portion 32 is moved by the well-known tilting device 15. by a predetermined amount tilting with axis line with the pile 1, but is relatively detached from the pile 1, in this case, as shown in FIG. 2, likewise both end portion as in the upper mold half 31 32 _1, 32 ₁ of the withdrawal operation from the pile 1 is delayed from the withdrawal operation of the central portion 32 ₂ so as to start.

Since the tilting device 15 is a well-known device,
Although not described in detail, the lower frame portion 32 is engaged and supported so that the fastening flanges 32a and 32a are positioned on a horizontal plane (diameter surface XX which is a dividing surface from the upper frame portion 32). It is configured to be tilted in a certain direction from a start state (a state shown in FIGS. 2A and 2A), and when the lower frame-shaped portion 32 is fixedly tilted, one of the fastening flanges 32a is tilted.
Stoppers 16 and 17 are provided at positions where they can collide with each other, and the lower frame-shaped portion 32 is relatively disengaged from the pile 1 by rolling the pile 1 out of the lower frame portion 32 by the impact of the collision with these stoppers 16 and 17. It is made to let. And Thus, in this embodiment, to perform ahead of the central portion 32 ₂ of the withdrawal operation to both end portion 32 _1, 32 _1, is disposed a stopper 16, 17 as follows. That is, as shown in FIG. 2, a stopper impinging on the central portion 32 ₂ corresponding portions (hereinafter referred to as "second engagement flange portion") 32a ₂ on one of the fastening flange 32a above (hereinafter referred to as "second stopper") 17
When the lower frame portion 32 is tilted by a predetermined amount θ ₂ (specifically, for example, in accordance with the tilt amount required to remove the lower frame portion 32 in the conventional method) At a position where it can collide with the second fastening flange portion 32a ₂ at both ends 32 of the fastening flange 32a.
_1, 32 ₁ each part (hereinafter, "first engagement flange portion" hereinafter) stopper (hereinafter "first stopper" hereinafter) 16 impinging on 32a ₁ corresponding to slightly the position of the tilting direction closer than a second stopper 17 That is, when the lower frame-shaped portion 32 is tilted by a predetermined amount θ ₁ (> θ ₂ ), it is arranged at a position where it can collide with the first fastening flange portion 32a ₁ .

The lower mold section 32 is released from the mold using the tilting device 15 including the stoppers 16 and 17 as follows.

That is, the lower mold section 32 is tilted in a fixed direction together with the pile 1 from the state where the mold release is started (FIG. 1A).
(A)).

[0039] When the lower mold half 32 by a predetermined amount theta ₂ tilting, second fastening flange part 32a ₂ collides with the second stopper 17, the detachment operation from the pile 1 of the central portion 32 ₂ so, the central portion 32 ₂ is deformed so as to relatively spaced from the pile 1 (FIG. (B). Meanwhile, the first fastening flange part 32a ₁ is without colliding with the first stopper 16, both end portion 32 _1, 32 ₁ withdrawal operation from the pile 1 is not initiated (Fig. (b)). in other words, in this state, the second stopper 1 of the second fastening flange part 32a ₂
The collision of the 7, the central portion 32 ₂ only by torsional moment acts, both end-side portion 32 ₁ is the central portion 32 _2,
32 will be torsionally deformed in tilt direction and reverse direction to _1.

[0040] Therefore, when such a torsional deformation occurs in the central portion 32 _2, in the axial direction, the upper mold half 3
In a manner similar to the lifting only one of the central portion 31 _2, in the axial direction of the pile 1, both end portion 32 _1, 32
So _{that 1} is deformed as drawn in the central portion 32 _{and second} directions. That is, in the both end portions 32 ₁ and 32 ₁ , as shown by a chain line in FIG. 3, the knot forming portion 3a is displaced in a direction approaching the deformation reference portion YY, and the knot forming portion 3a
The second side surface 3a ₂ is to be displaced in a direction away from the second side surface 1a ₂ sections 1a, a second side 1a _2, 3a of
The mutual pressing force at the contact portion C of ( ₂ ) is greatly reduced. As a result, the initial demolding force at the node portions at both end portions 32 ₁ and 32 ₁ is extremely small. Incidentally, as in the upper mold half 31, although Hifushi partial initial demolding force is uniform in the axial direction of the lower mold half 32, node portion early demolding force is small in the central portion 32 _2, both ends since the increase in the side portions 32 _1, 32 _1, it is obvious that it is possible to easily center portion 32 ₂ of the withdrawal operation described above.

Then, as described above, the second fastening flange 3
2a ₂ is in after colliding with the second stopper 17, with a slight time difference, the first fastening flange 32a ₁ collides against the first stopper 16. That is, the central portion 32 ₂
Subsequently, the operation of separating the both end portions 32 ₁ , 32 _{1 from} the pile 1 is started (FIGS. 9C and 9C). In this case, node portion early demolding force at both side portions 32 _1, 32 _1, as described above, it is reduced by being deformed by the second stopper 17 ahead of the opposite ends portions 32 _1, 32 ₁ Therefore, the relative detachment operation of the both end portions 32 ₁ and 32 _{1 from} the pile 1 subsequent to the central portion 32 ₂ is also easily performed.

At this time, the initial demolding force of the knot portion at both end portions 31 ₁ , 31 ₁ is, as described above, the central portion 3 1.
1 ₂ both end portion 31 _1, 31 since it is extremely small by prior lifted it to _1, both end portion 31 _1, 3 that is performed subsequent to the central portion 31 ₂
Desorption operation from 1 ₁ of the pile 1 is also easily performed.

As described above, the lower mold frame portion 32 has the predetermined amount θ ₁
By being tilted, the central portion 32 ₂ and the both end side portions 32 _1, 32 ₁ is disengaged from the pile 1, the pile 1 will be out rolling from the lower mold half 32, and disengagement of the lower mold portion 32 The mold is completed (FIGS. (D) and (D)).

Therefore, it is possible to remove the lower mold section 32 very easily as compared with the conventional method in which the entire lower mold section is separated from the pile at once.

As described above, according to the demolding method according to the present invention, the demolding operation of the both mold sections 31, 32 can be performed efficiently, and the pile production efficiency can be greatly improved. You can.

Incidentally, both end portions 31 ₁ , 31 ₁ or 32
₁ and 32 ₁ are separated from the pile 1 by the central portion 31 _2.
Or 32 ₂ means to start is delayed from the withdrawal operation is optional and is not limited to the embodiment described above. For example, the lower mold section 32 is also inverted, and the suspension beams 11 are formed similarly to the upper mold section 31.
By lifting while bending and deforming convexly,
It can be demolded.

[0047]

As can be easily understood from the above description, according to the demolding method of the present invention, the initial stage of the joint portion inevitably generated by applying and releasing the tension to the PC steel rod group. The demolding force can be reduced as much as possible, and the demolding of the upper and lower mold sections can be efficiently and easily performed, and the pile manufacturing efficiency can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a side view showing a demolding step of an upper mold part by a demolding method according to the present invention.

FIG. 2 is a vertical sectional front view showing a step of removing a lower mold section by a removing method according to the present invention.

FIG. 3 is a vertical sectional side view of a main part showing a deformation action of both end portions in a state where a detaching operation of a central portion of an upper mold portion or a lower mold portion has started.

FIG. 4 is a partially cutaway longitudinal side view showing a knotted pile forming die used in the demolding method according to the present invention.

FIG. 5 is a longitudinal sectional side view of a main part showing an initial stage of a knotted pile forming process.

FIG. 6 is a vertical sectional front view taken along the line VI-VI of FIG. 4;

FIG. 7 is a longitudinal sectional side view corresponding to FIG. 3 showing a deformed state of a mold and a pile in a state where tension application to a PC steel bar is released.

FIG. 8 is a longitudinal sectional side view of a partially cutaway showing a knotted pile.

FIG. 9 is a side view showing a demolding step of an upper mold frame portion according to a conventional method.

FIG. 10 is a vertical sectional front view showing a step of removing a lower mold section by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pile, 1a ... Section, 1b ... PC steel bar, 2 ... Forming die,
3 ... mold, 3a ... node forming part, 3b ... end flange, 4 ...
Tension applying member, 11 ... hanging beam, 13, 14 ... hanging
Tool, 15: tilting device, 16: first stopper, 17: second
Stopper, 31 … Upper frame part, 31₁... both upper formwork
End part, 31_Two… Central part of upper mold part, 31a… Tightening
Tying flange, 32 ... Lower mold part, 32₁… Of the lower mold section
Both ends 32_Two... the central part of the lower mold part, 32a ...
Fastening flange, 32a₁... First fastening flange portion, 32
a_Two... Second fastening flange portion.

Claims (1)

[Claims] 1. A prestressed high-strength concrete knotted pile in which a plurality of axially extending PC steel rods are buried, is formed by a half-cylindrical formwork having upper and lower formwork portions. A method of detaching each form part from the pile in a direction perpendicular to the axis direction of the form part. A method of removing a knotted pile forming mold, wherein the method is started by delaying from a part separating operation and starting.