JPS6334889Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a formwork for manufacturing centrifugally formed concrete products such as concrete piles, concrete poles, and humid pipes.

Formwork for the production of centrifugally cast concrete products includes:
During use of the formwork, stress is generated due to the reaction force of tension on the reinforcing bar cage, imbalance of the fresh concrete poured into the formwork, and stress due to vibration caused by bending of the formwork. Furthermore, since many reinforcing members, flanges, tires, etc. are welded to the formwork, the heat input during welding is large, and therefore residual stress due to welding acts. If these stress values exceed a certain limit, the formwork will deform after a relatively small number of uses due to repeated use, and will no longer be able to rotate smoothly in the centrifugal molding machine, eventually becoming unusable. Another drawback is that many reinforcing members are welded to the formwork body, which increases the number of manufacturing processes and increases manufacturing costs.

This project was proposed in order to eliminate such drawbacks, and in a formwork for manufacturing centrifugally formed concrete products with a welded structure, the reinforcing member of the form body plate is omitted and the reinforcing member is welded. The body plate is thickened to have the same strength, and semicircular tires are welded to the body plate at intervals of 4 m to 6 m, so that residual stress due to welding is removed. This relates to formwork for manufacturing centrifugally formed concrete products.

When the inventors of the present invention measured the stress generated during the operation of the currently widely used formwork, it was confirmed that the generated stress alone does not cause deformation even if the formwork is used repeatedly, and furthermore, the formwork deformation does not occur even if the formwork is repeatedly used. It has been confirmed that the cause is that the generated stress is added to the area where the residual stress generated by welding during manufacturing is applied.

This project was proposed based on this knowledge, and by making the formwork body plate thicker as described above, reinforcement can be achieved even if the reinforcing member that is conventionally welded to the formwork body plate is omitted. It is possible to provide the same level of strength as the conventional form body plate with members attached, and the amount of heat input due to welding for attaching reinforcing members is eliminated. However, in addition to attaching reinforcing members, welding is required to attach flanges, tires, etc., and the length of the formwork is insufficient for one steel plate, so it is necessary to create the formwork body plate. requires welding multiple steel plates. Therefore, if the form body plate is simply made thicker, the stresses caused by the various welding processes described above remain.

In this case, the form body plate is not only made thicker, but also the residual stress caused by welding is removed. Furthermore, since the tires are spaced roughly between 4 m and 6 m, the number of welding points is very small.

Thus, according to the present proposal, there will be no deformation of the formwork,
Not only can the service life of the formwork be greatly extended, but also the adhesion between the upper and lower formwork is improved, cement paste leakage is reduced, high quality concrete products can be obtained, and tire wear is also reduced. Become.

The reason why this kind of residual stress removal from formwork has not been carried out in the past is thought to be due to the presence of residual stress due to welding as a factor in the deformation of the formwork, but stress measurement and theoretical analysis using actual machines have not been conducted. This was because they did not understand that the residual stress caused by welding was a deformation of the formwork, and because there was a risk that large distortions would occur when the residual stress was removed due to the structure of the formwork. As a result of experiments, this kind of distortion poses no practical problem, and after removing the residual stress, the tire is ground and the rotational balance is adjusted.
This point does not pose any problem.

The present invention will be described below with reference to the illustrated embodiments.

Figures 1 and 2 show the conventional formwork for manufacturing centrifugally formed concrete products and the state of its use.
is a form body plate of a semi-cylindrical upper and lower form frame, a tightening flange 2 is welded to each connecting end, and semi-circular tires 3 are welded at predetermined intervals in the longitudinal direction, Further, reinforcing members 4, 4' extending in the longitudinal direction as well as in the circumferential direction are welded to the frame body plate 1.

Therefore, when assembling the formwork, the opposing upper and lower formwork body plates 1
The tightening bolts 5 are inserted and tightened across the flanges 2, 2, and the cylindrical formwork is assembled.
An annular tire 3 is formed, and during centrifugal molding, the tire 3 is mounted on a drive roller 6 of a centrifugal molding machine,
It is designed to be driven and rotated by the same drive roller 6.

When centrifugally forming a concrete product using the formwork, in both the upper and lower formworks, which are divided into two parts,
After inserting the reinforcing bar cage into the formwork body plate 1 of the lower formwork,
The formwork is assembled by inserting and tightening the tightening bolts 5 through the upper and lower formwork body plates 1 across the respective flanges 2, and after applying tension to the reinforcing bars, fresh concrete is poured into the ends of the formwork through the injection pipe. The concrete is poured evenly into the formwork, the tire 3 of the same formwork is placed on the driving roller 6 of a centrifugal molding machine, the driving roller 6 is driven and rotated to form the concrete into a cylindrical shape by centrifugal force, and then It is removed from the mold when it reaches a predetermined strength after steam curing.

However, in conventional formwork for manufacturing concrete products, stress due to the reaction force of tension on the reinforcing bar cage,
Stress due to vibrations caused by unbalance of fresh concrete and bending of the formwork is generated during use of the formwork, and furthermore, the reinforcing members 4, 4', flanges 2 tires 3, etc. are welded to the formwork body plate 1. Due to the large amount of heat input during the welding process, residual stresses from welding act, and due to these stresses, the formwork deforms after a relatively small number of uses due to repeated use, making it unusable.

3 to 7 show an embodiment of the formwork according to the present invention, in which reinforcing members 4 and 4' are omitted from the formwork body plate 1 of the semi-cylindrical upper and lower formworks, and as will be described later, The reinforcing members 4, 4'
Even if the reinforcing member is removed, it is constructed to have the same strength as the conventional formwork with the reinforcing member.

In addition, the other structure is substantially the same as the conventional formwork, and the method of use is also completely the same. In the figure, parts equivalent to the conventional formwork are given the same reference numerals.

The flanges 2, 2 shown in FIG. 5 and the form body plate 1 are preferably partially welded as shown in the welded part w in FIG. 6. In addition, although the welds in the longitudinal direction of the formwork shell are not shown in the figure, in reality,
There are welds.

In the present invention, the formwork with these residual stresses is annealed using, for example, an annealing device to remove the residual stress caused by welding. Note that if the thickness of the form body plate is as thin as in the past, stress may be generated due to annealing, but this problem is eliminated in the present invention.

Figure 8 shows a deformation limit diagram for the stress value of the formwork shell plate, where the horizontal axis is the average stress of multiple specimens, and the vertical axis is the stress amplitude when vibration is applied to each stress value application state of the specimen. In addition, σ _b is the tensile strength of the steel used in the formwork of the specimen (41 Kg/mm ² ), σ _y is its yield point (23 Kg/mm ² ), σ _e is its set limit, and σ _w is the butt welding strength. It shows joint fatigue strength (5Kg/mm ² ), and if the stress value of the formwork shell exceeds the shaded area, the formwork will become deformed and unusable after a relatively small number of uses due to repeated use of the formwork. It shows that it will become.

The stress of the formwork body plate 1 at point X (see Figs. 3, 6, and 7) next to the mounting part of the tire 3 of the formwork body plate 1 measured in the actual machine is shown in Fig. 8. Point A (maximum stress on the tensile side) and Point B (maximum stress on the compression side) are shown,
It can be seen that if the residual stress due to welding is zero, no deformation will occur in the formwork.

Next, when residual stress due to formwork welding is applied, the stress generation area becomes points C and D, and at point C, in order to prevent the formwork from deforming, it is necessary to remove the residual stress due to welding. It was discovered in a test by.

Based on the findings from the test results using the actual machine mentioned above, in order to remove residual stress due to welding, the formwork was annealed using an annealing device or preloaded using a preloading device, and as a result, the residual stress was 13
Kg/mm ² (maximum stress on tension side) - 5Kg/mm ² (maximum stress on compression side). When the stress generated by the use of the formwork is added to this, the stress-generating parts become points E and F, which fall within the deformation limit range, and it can be seen that no deformation occurs even if the formwork is used repeatedly.

Therefore, when the formwork body plate 1 is made thicker to remove residual stress in the welded structure formwork as in the present proposal, the deformation caused by repeated use that occurs in conventional formwork is prevented, and the service life of the formwork is reduced. Not only is it significantly longer than before, but the adhesion between the upper and lower formwork is also improved, reducing cement paste leakage, making it possible to obtain high-quality concrete products, and preventing tire wear. .

In addition, the thickness of the form body plate 1 in this proposal is 8 mm to 12 mm based on the experimental results of the following points.

(i) To reduce residual stress caused by welding,
It must have the thickness required for strength when the various reinforcing materials that were conventionally welded are abolished.

(ii) It must have a thickness necessary to practically minimize distortion caused by annealing.

(iii) It has an economical thickness that does not require changes to conventional equipment due to increased weight of the formwork.

(iv) When the tire pitch is roughened to 4 m to 6 m in order to reduce the stress generated in the formwork and make the formwork rotate more smoothly during centrifugal molding, it must have a thickness necessary for strength.

Next, we will discuss the correlation among formwork body thickness, formwork length, and tire pitch.

(i) The relationship between the form body plate and the tire pitch is as shown in FIG. 9 when the tire and the drive roller of the centrifugal molding machine are in constant contact and the stress generated is constant.

(ii) In order to ensure constant contact between the tire and the drive roller of the centrifugal molding machine, when the formwork length is 15 m, the relationship between the tire pitch and the permissible initial bending of the formwork is as shown in Figure 10. .

Therefore, when roughening the tire pitch, a tire pitch of 4.6 m is preferable, which maximizes the allowable initial bending of the formwork, but when using an existing centrifugal molding machine, the roller pitch of the centrifugal molding machine should be adjusted as shown in Figure 11. is 2m, and the formwork length is 2m pitch, so the tire pitch is 4m.
m to 6 m. Therefore, the thickness of the form body plate is 8 mm to 10 mm, as is clear from FIG.

The formwork with rough tire pitch in this way has a tire pitch of 4m or 6m depending on the length of the formwork.
Figures 11a, b, and c show the tire arrangement in each formwork with formwork lengths of 11m, 13m, and 15m. At this time, in order to keep the stress generated in the formwork below a certain value, the overhang A' is kept below a certain value.

(iii) As the formwork diameter increases, the weight carried by the formwork increases, but even if the thickness is the same, as the formwork diameter increases, the strength also increases, so change the formwork body plate thickness depending on the formwork diameter. There's no need.

In this way, according to the present invention, the pitch of the tires 3, which are disposed around the outer periphery of the formwork body plate 1 and rotate the formwork by contacting the centrifugal forming machine drive roller, is made rough, so that each formwork tire is driven securely contacts the roller,
The stability of the formwork during rotation is increased, the impact force caused by the collision between the formwork tires and the drive roller is reduced, and there is less negative impact on both the formwork and the drive roller, which further increases the service life of the formwork. However, due to the reduction in the number of tires and roughening of the tire pitch, the permissible initial bending of the formwork becomes large, and the manufacturing accuracy can be rough.
This reduces manufacturing costs.

Furthermore, since a formwork with a rough tire pitch is used, there is an advantage that the number of driving rollers of the centrifugal molding machine can be reduced.

In addition, when operating a formwork with a coarse tire pitch using the drive roller equipment of a general centrifugal molding machine, it is practical if the tire pitch is an integral multiple of the generally used tire pitch.

The embodiment shown in FIGS. 12 and 13 shows a case where the present invention is applied to a formwork using a wedge instead of the tightening bolt 5, and the flange 2 of the upper formwork body plate 1A
The wedge piece 7 fixed to the upper surface of A is attached to the lower formwork body plate 1B.
The wedge is engaged with the wedge surface of the wedge receiving piece 8 attached to the flange 2B of the flange 2B, thereby tightening both the upper and lower formworks.

When the present invention is applied to the formwork shown in the figure, there is no deformation of the formwork, so the adhesion between the upper and lower formworks is good, there is no need to adjust the wedge force to deform the formwork, and the number of wedges used can be reduced. There is an advantage.

In FIGS. 14 and 15, a spacer 9 is arranged on the upper surface of the flange 2B of the lower formwork body plate 1B, and bolts 5 are used to connect the flange 2A of the upper formwork body plate 1A and the flange 2B of the lower formwork body plate 1B. A case is shown in which the present invention is applied to a formwork in which a gasket 10 is interposed between the flanges 2A and 2B when tightening through the flanges 2A and 2B. The sealing performance of the gasket 10 is improved, leakage of cement paste is eliminated, and a high-quality concrete product is obtained.

On the other hand, when the leakage of cement paste is eliminated, cement paste does not enter between the tire 3 and the drive roller 6, so the friction between them is reduced, and the formwork is not deformed, resulting in high durability. This is what the formwork is made of.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the state of use of a conventional formwork for producing centrifugally formed concrete products, and Figure 2 is a
3 is a plan view showing an embodiment of a form for manufacturing centrifugally formed concrete products according to the present invention, FIG. 4 is a view taken in the direction of arrows in FIG. 3, and FIG. Figure 6 is an enlarged view of the part shown in Figure 3. Figure 7 is a partially enlarged view of Figure 3.
The figure is a deformation limit diagram for the stress value of the formwork, and Figure 9 is a diagram showing the relationship between the tire pitch and the formwork body plate.
Fig. 10 is a chart showing the relationship between tire pitch and allowable initial bending of the formwork, and Fig. 11 a, b, c, and d show the tire arrangement conditions in formworks of various formwork lengths, as well as the relationship between the tire pitch and the allowable initial bending of the formwork. An explanatory diagram showing a roller pitch,
Fig. 12 is a front view of main parts showing another embodiment of the formwork for manufacturing centrifugally formed concrete products according to the present invention, Fig. 13 is a vertical side view thereof, and Fig. 14 is a manufacturing form for centrifugally formed concrete products according to the present invention. FIG.
4 is an enlarged view of the part shown in FIG. 4. 1... Form body plate, 2... Flange, 3... Tire, 5... Bolt.

Claims (1)

[Scope of utility model registration request] In a formwork for manufacturing centrifugally formed concrete products having a welded structure, the reinforcing member of the formwork body plate is omitted, and the body plate is thickened so as to have the same strength as when the same reinforcing member is welded. A formwork for manufacturing a centrifugally formed concrete product, characterized in that annular tires are welded to the body plate at intervals of 4 m to 6 m, and residual stress due to welding is removed.