JPH0243692Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a formwork for a pretension-type precast concrete manufacturing device in a prestressed concrete product manufacturing factory.

[Conventional technology]

Prestressed concrete (hereinafter referred to as PC)
When manufacturing a component as a pre-cast product using the pretension method, as shown in Fig. 2, a pre-tensioned PC steel material 2 extending several tens of meters long is stretched between the abutments 1 and 1a of the pretension PC component manufacturing device via fixing plates 3 and 4. This PC steel material 2 is placed under tension with jacks 5, and concrete is poured by arranging formwork 6 to surround this PC steel material.After the concrete hardens, the jacks 5 are loosened to release the tension in the PC steel material 2. Then, the tension force of the prestressed steel material 2 acts on the concrete, making it possible to manufacture a high-strength prestressed material 7.

Many of the PC members manufactured by such a pretension PC member manufacturing apparatus are large elongated members such as beams and girders.

Conventionally, in the manufacturing process of such PC components,
When introducing prestressing to concrete,
Since the PC member 7 produces camber due to tension,
There was a problem in which the concrete at the bottom of the longitudinal end of the PC component product was damaged.

As the bottom plate 11 of the PC component manufacturing apparatus ages, it becomes rough and distorted, and as a result, paste tends to leak from the contact area with the side formwork 12, requiring replacement.

[Problem that the invention attempts to solve]

This invention was developed to eliminate damage to the ends of PC members, as well as to avoid paste leakage and replacement of the bottom plate, and the purpose is to provide a formwork that eliminates these drawbacks.

[Means for solving problems]

This invention is a pretensioning precast concrete formwork for manufacturing PC members.
This is a PC member formwork with a double bottom plate, characterized in that the formwork is constructed by laying one seamless plate on the bottom plate via a lubricant.

[Effect]

Since the present invention is configured as described above, it produces the following effects.

(b) The seamless plate acts as an elastic material, and a lubricant is interposed between the seamless plate and the bottom plate of the formwork, so when prestress is introduced to the PC member, the PC member and the bottom plate contract. The friction between the two is significantly reduced. Therefore, there is no movement of the formwork bottom plate,
Also, due to the occurrence of camber in PC parts,
There will be less damage to the bottom of the concrete at the end of the PC member.

(b) Since the seamless board acts as an elastic material, it prevents paste from leaking between the side formwork and the side formwork during concrete pouring.

〔Example〕

A 6 mm thick steel plate coated with grease was placed between the bottom plate and the bottom plate of a pretension type PC component manufacturing equipment with a span of 60 m.

FIG. 1 shows its cross section, and the PC member 7 is manufactured by placing a seamless plate 13 on the bottom plate 11 and combining it with the side frame 12.

The width of this seamless steel plate was equal to that of the conventional formwork bottom plate, and it was connected to a length of 20 m by welding, and the welded part was polished flat to create a single seamless plate. The thickness of this seamless board may be 4.5 mm, but
If it is less than 4.5mm, welding will easily be distorted and it will be difficult to finish it into a long flat plate, so 4.5mm
It is better to set it to above.

On the other hand, if the thickness exceeds 6 mm, the favorable effect of elasticity will be diminished, so it is preferably 6 mm or less.

Grease was applied between the bottom plate and the seamless plate.

With this formwork, girder width 600mm x height 1000mm x length 20
When we manufactured a PC girder with an I-shaped cross section, there was no paste leakage, and when prestressing was introduced, no chipping occurred at the end of the PC member.

[Effect of idea]

Since the present invention is configured as described above, it has the following effects.

(a) No damage occurs at the ends of PC members.

(b) There is no paste leakage.

(c) There was a mark on the bottom of the conventional product from the seam of the bottom plate, but this has disappeared. This is particularly preferred in the case of viaducts.

(d) It is no longer necessary to replace the bottom plate, and the seamless plate of the present invention can be replaced. Therefore, maintenance costs are significantly reduced.

(e) As an effect of the example, by using a seamless board with a length that matches the product length, the length can be determined accurately.
PC parts can be manufactured easily, products with uneven lengths can be avoided, and the number of man-hours required for length setting has been reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a formwork for a PC member, and FIG. 2 is an overall side view of the pretension PC member manufacturing apparatus. 7...PC member, 11...bottom plate, 12...side formwork, 1
3... Seamless board.

Claims (1)

[Scope of utility model registration request] A pre-tensioned precast concrete formwork with a double bottom plate, characterized in that a single seamless plate is laid on the bottom plate via a lubricant.