WO1994029090A1

WO1994029090A1 - Method and apparatus for manufacturing pc concrete plate

Info

Publication number: WO1994029090A1
Application number: PCT/KR1994/000067
Authority: WO
Inventors: Kun Hee Suh
Original assignee: Kun Hee Suh
Priority date: 1993-06-11
Filing date: 1994-06-11
Publication date: 1994-12-22
Also published as: CN1041906C; KR950000331A; AU687070B2; JP2780874B2; JPH08506291A; CN1127489A; KR960012035B1; AU6984694A

Abstract

The invention relates to a method and an apparatus for manufacturing PC concrete plates (50). More particularly, the invention relates to a method and an apparatus (20) for manufacturing PC concrete slabs (50) which are suitable for mass production. The apparatus (20) for manufacturing PC concrete plates (50) of the invention comprising a pair of rails (21) positioned parallel with each other at the upper portion of the apparatus (20), a plurality of sliders (22) slidable on the rails (21), and a molding assembly (26) formed by assembling a plurality of molding partitions (28) suspended separately from the sliders (22) so that they can be brought in contact with each other. Also, the method of the invention comprises the steps of suspending horizontally movable molding partitions (28), cleaning said molding partitions (28) and then spraying releasing agents onto said molding partitions (28), bringing said molding partitions (28) into contact with each other to form a molding assembly (26), pouring concrete mortar into the molding assembly (26), curing the concrete mortar in a curing site (4), and finally removing the cured products (50) from the molds (25) by disassembling the molding assembly (26). The apparatus (20) and method of the invention allows easy handling and transfer of the heavy molds (25), extends the effective operation time of stationary facilities, and thereby reducing the manpower and operation time, and are suitable for mass production.

Description

METHOD AND APPARATUS FOR MANUFACTURING PC CONCRETE

PLATE

Background of the Invention Field of the Invention

The present invention relates to a method and an apparatus of manufacturing pre-cast ("PC") concrete plates for making slabs, fences, and so on. More particularly, the invention relates to a method and an apparatus for manufacturing PC concrete plates suitable for mass production.

Description of the Related Art

In manufacturing PC concrete slabs in the prior art, the slabs and molds for molding the slabs are heavy, and in particular, the molds are made of large steel plates which are not easily carried, assembled, or removed. Therefore, large PC wall members are molded by a method wherein a box-type of mold is formed by setting walls about the peripheries of a steel plate laid on the ground, concrete mortar (composed of cement, sand and/or lime) is poured into the mold, the poured concrete is manually vibrated to remove air bubbles using a vibrating rod and the surface of the concrete mortar is made even, the mold is covered with a cover such as a tent, and the concrete is then hardened. In order to facilitate the release of the molds, the upper portions of the walls must be inclined outward from the mold. In order to form rectangular or circular openings (such as see-through openings of fences or window openings) through the molded walls, the side molding members of the openings must be inclined, and the upper areas of the members must be made wider than the lower areas. Accordingly, there are aesthetic problems in that the outer surfaces of the resulting products are inclined and the dimensions of the front and the rear surfaces of the opening formed in the molded product are unequal. In addition, ' the prior art techniques have disadvantages in that double-side molding is impossible and work space is wasted since the mold must be installed on the ground and the upper surface of the poured concrete mortar must be manually evened; this requires intensive labor and is not suitable for mass production.

To solve the above prior art problems, Korean Utility Model Publication No. 85-1512 published on July 25, 1985 suggests a molding assembly for manufacturing PC concrete fences and handrails in stacks, as illustrated in Figures la and lb, wherein the molding assembly A comprises molding plates 1 , 1 ' , 1 ",... with projections 2 projected vertically and equally spaced on their inner and outer surfaces, transverse end pieces 4 with adequately spaced flow grooves 3 positioned on their lower ends, and elastic members 7 with a plurality of through-holes 5 and recesses 6 on both sides. To assemble and use this assembly, the recess 6 on one side of an elastic member 7 is engaged with the projection 2 of the first plate 1 , spacer rods 8 are fitted in adequate through-holes 5, and the projection 2 of the second plate 1 ' is engaged with the recess 6 on the other side of the elastic member 7. In this manner, the plates 1, 1' , 1 ",... are stacked horizontally, and elastic members 7 are positioned between the plates with the projections 2 and the recesses 6 engaged. Then, the assembly is fixed by suitable pressure exerted with a fixing plate 10. The spacer rods 8 maintain constant distances between plates 1 , 1', 1 ", and prevent the elastic members 7 from being excessively compressed so that they will not permanently deform.

However, the foregoing assembly A has a disadvantage in that the assembly itself cannot be vibrated directly since the first plate 1, the fixing plate 10 and the other plates 1 ' , 1 " between them are assembled integrally and installed on the ground; thus, each space between the plates 1, 1', 1 ",... should be manually vibrated with rods to remove air bubbles from the inside of the concrete mortar and to completely fill the spaces. Therefore, the molding requires a lot of manual labor and a long molding time. Further, it is very complicated and inefficient since when assembling the assembly A, the plates and the elastic members 7 are washed individually, and the elastic members 7 are assembled one by one. And, when removing the assembly, the elastic members 7 are removed individually from respective molded products. In addition, since the facilities including a pressure-exerting fixing device securing the assembly A is very expensive, and the fixing device can generally secure only one assembly A per day, the investment is wasted and the productivity is not improved over the prior art.

Brief Summary of the Invention

Therefore, an object of the invention is to provide a method and an apparatus for continuously manufacturing PC concrete plates which eliminate such problems, is capable of easily washing and assembling the molds, and do not require an additional pressure exerting device.

Another object of the invention is to provide a method and an apparatus for manufacturing PC concrete slabs which can vibrate the entire molding assembly to remove air bubbles entrained in the molds and to fill concrete mortar into the molds densely.

Still another object of the invention is to provide a method and an apparatus for manufacturing PC concrete slabs which extend the effective operating time of the apparatus including the expensive fixing device and to make the apparatus suitable for mass production by making it possible to assemble the molding assembly several times per day.

The above and other objects can be accomplished by providing an apparatus for manufacturing PC concrete slab comprising a pair of rails positioned parallel with each other at the upper portion of the apparatus, a plurality of sliders slidable on the rails, and a molding assembly formed by assembling a plurality of mold partitions suspended separately from the sliders so that they can be brought in contact with each other.

The objects can also be accomplished by providing a method for manufactur¬ ing PC concrete slabs, comprising the steps of suspending horizontally movable molding partitions to which molding members are attached, cleaning the partitions and then sparying releasing agents onto the partitions, bringing into contact the partitions with each other to form a molding assembly, pouring a concrete mortar into the molding assembly while the assembly is suspended over and vibrated on base members, curing the concrete mortar in a curing site, and finally removing the cured products from the molds by disassembling the assembly after the curing is completed.

In accordance with the invention, a vibrating means is provided separately or integrally with the molding assembly to vibrate the assembly; this reduces the necessary manpower and time as compared with the conventional methods using a manually operated vibrator.

The molding partitions according to the invention may -be provided with combinations of side molding members, bottom molding members, and end pieces of various shapes in order to make it possible to mold various shapes and patterns.

Brief Description of the Drawings

The present invention is embodied in greater detail by means of the accompanying drawings, wherein:

Figures la and lb are a perspective view and a side-elevation view, respectively, diagrammatically showing an apparatus for manufacturing PC concrete slabs according to the prior art;

Figure 2 is a perspective view of an apparatus for manufacturing PC concrete slab according to a first embodiment of the invention;

Figure 3 is an exploded perspective view of the side molding members used in the apparatus of Figure 2;

Figure 4 is an enlarged perspective view of the circle A of Figure 2;

Figure 5 is a sectional view taken along line V-V of Figure 2 showing the assembled state of the molding assembly of the first embodiment of the invention;

Figure 6 is a diagrammatic view showing a method for manufacturing a PC concrete slab according to the invention;

Figures 7a to 7c are a cross-sectional view of the mold, a perspective view of the mold, and a view showing the use of the mold, respectively, according to the second embodiment of the invention;

Figures 8a and 8b are a cross-sectional view of the mold and a perspective view of the mold, respectively, according to the third embodiment of the invention;

Figures 9a and 9b are a cross-sectional view of the mold and a perspective view of the mold, respectively, according to the fourth embodiment of the invention; and Figure 10 is a perspective view showing an example of the final products obtained by still another embodiment of the invention.

Description of the Preferred Embodiments

Figure 2 shows an apparatus 20 for manufacturing PC concrete slab according to the invention. The apparatus 20 comprises a pair of I-beam shaped rails 21 positioned parallel with each other at the upper portion of the apparatus; a plurality of sliders 22 slidable on the rails 21 ; a pair of I-beam shaped support members 23 positioned parallel with each other outside the rails 21; wire rope support members^' 24 fixed to the support members 23; a molding assembly 26 including a plurality of molds 25 formed by a plurality of molding partitions; a base member 27 including a base plate 27a positioned under the molding assembly 26 and a pair of I-beams 27b fixed parallel with each other under both sides of the base plate 27a; chains 29, each of which has one end fixed to the slider 22 and the other end removably connected to the upper side of the molding partition 28 to support the molding partitions 28 forming the molds 25 of the molding assembly 26 from the rails 22; and wire ropes 30, each of which has one end fixed to the support member 24 and the other end having a hook 30a wherein the hook is removably connected to an eye 27c of the I- beam 27b of the base member 27 to support the base member 27 removably from the support member 23 which has been moved vertically by a suitable means for supporting the molding assembly 27.

The I-beam shaped rails 21 and the support members 23 are fixed by vertical frames (not shown). The width between the two rails 21 and the height of the rails are designed to horizontally suspend the molding assembly 26 by chains 29. The support members 23 are positioned far enough outside the rails in order not to interfere with the sliding of the sliders 22 on the rails 21. The sliders 22 facilitate the horizontal movement of the molding partitions 28 suspended by the chains, each of them has one end fixed to each slider 22. The wire rope support members 24 are fixed to the support members 23 by a suitable means and are designed to support the assembled molding assembly 26 without the aid of the chains 29. The chains 29 are provided with a hook 29a on one end and are removably connected with an eye 28a provided at the upper corners of the molding partition 28. The wire ropes 30 are also provided with the hook 30a and are removably connected with the eye 27c provided on the I-beam 27b. The wire ropes 30 are used for enhancing the vibrational freedom, as will be described in the later part of this specification. The length of each wire rope is short enough so that when the base supporting the assembled molding assembly 26 is lifted by a forklift, the hooks 30a of the wire ropes 30 hook on the eyes 27c of the base 27. The molding assembly 26 can be suspended by the wire ropes 30 only. Reference numeral 22a indicates rollers.

As stated above, the molding assembly 26 is structured by assembling the molding partitions 28 forming a plurality of unit molds 25 by bring the molding partitions 28 in contact with each other in a horizontal direction. On the two sides of each molding partition 28 are provided a plurality of side molding members 31 which are fixed vertically, oppositely, and are constantly spaced, bottom molding members 32 fixed transversely and spaced by a predetermined distance from the lower ends of the side molding members 31 to mold the lower end piece of the molded product, L-shaped upper corner members 33 each having one end contacting tightly with the upper corners of the side molding members and another end extended to the upper edges of the molding partitions 28 to mold the upper end piece of the molded product, and L-shaped lower corner members 34, each having one end tightly contacting the lower corner of the side molding member 31 and another end tightly contacting the upper edge of the bottom molding member 32 to mold the lower end piece of the molded product. The side molding members 31 , the bottom molding members 32, and the upper and lower corner members 33, 34 provided on each of the two molding partitions in contact with each other are designed to bring them into contact with each other and to form a mold 25 when assembled. Accordingly, the molding assembly 26 including a plurality of molds 25 can be provided by bringing them horizontally into contact with each other and then fixing the molding partitions 28.

As can be seen clearly from Figure 3, the side molding member 31 is comprised of a main body 41 and terminal members 42 at both ends. The body 41 is hollow and has a flat U-shaped cross-section. The top surface of the body 41 is separated into two surfaces 41b by a recess 41a formed longitudinally on the center of the body. The two side walls 41c of the body are inclined so that the top surface is narrower than the bottom surface of the body. Each terminal member 42 includes a connecting portion 42a which is inserted into the hollow end of the body 41 and fixed thereto with screws 43, a top surface 42b being flush with the two surfaces 41b of the body 41, inclined side walls 42c being flush with the side walls 41c of the body 41 , an end wall 42d, and connecting walls 42e between the end wall 42d and the side walls 42c. The side walls 42c, the end wall 42d, and the connecting walls 42e are inclined to facilitate release of the side molding member 31 from the completely hardened product. As shown in Figure 3, the connecting wall 42e is curved while the side wall 42c and the end wall 42d are flat. The curved portion is so shaped to form a predetermined pattern on the corners of the openings of the molded product.

Figure 4 shows clearly the bottom molding member 32 and the lower corner member 34. The member 32 is an elongate member with a rectangular groove 32a. An elongate elastic seal 46 is fitted into the groove. The elastic seal is pressed against the adjacent elastic seal when assembling the molding assembly to prevent the concrete mortar from leaking. The member 34 is substantially L-shaped and one end of which tightly contacts the upper edge of the bottom molding member 32 and the other end of which tightly contacts a side of the end member 42 of the side molding member 31. That is, the other end of the lower corner member 34 has a shape complimentary with the shapes of the side wall 42c and the connecting wall 42e of the end member 42 to tightly contact the side wall 42c and the connecting wall 42e.

The shape of the upper corner member 33 is substantially identical with that of the lower corner member 34. The only difference is that one end of the upper corner member extends to the upper edge of the molding partition 28 while one end of the lower corner member 34 tightly contacts the upper edge of the bottom molding member 32.

Figure 5 Shows a sectional view, taken along the line V-V of Figure 2, of the molding assembly in an assembled state. As discussed above, the molding assembly 26 is formed by bringing the molding partitions 28 horizontally into contact with the side molding members 31, the bottom molding members 32, the upper corner members 33, and the lower corner members 34 provided on both sides of the side molding members 31, and tightly fixing a plurality of molding partitions 28 by fastening bolts 44 passing through the molding partitions 28 with nuts 45. It will be easily understood that the side molding members 31, etc., are provided on only the inner sides for the molding partitions 28 positioned at the ends of the molding assembly 26. Turning now to Figure 2, each molding partition 28 is designed to be horizontally movable while being suspended from the rails 21 by chains 29 and sliders 22. Therefore, even if a plurality of molding partitions 28 are provided, each molding partition 28 is easily carried toward both ends of the rails 21 so that the space for spraying a releasing agent onto the partitions, and cleaning, assembling, and removing the molding partitions 28 can be minimized. Unlike the prior art in which such partitions must be carried by an excavator or a crane because of their heavy weight, the invention allows easy transportation of the molding partitions 28 by the sliders 22 on the rails 21.

Now, a method for manufacturing a product 50, such as PC concrete slabs, employing the apparatus 20 according to the invention will be discussed with reference to Figures 2 and 6.

Step 1: Cleaning of the molds

After each molding partition 28 is transferred to a certain position along the rails 21 , its surface with side molding members 31, etc. , thereon is cleaned with brushes, etc. Cleaning can be easily conducted by washing the partitions while transferring them one by one and then pushing them to the assembling position. Motor-operated brushes can be used to enhance the productivity because of the large dimensions of the molding partition 28 itself. In particularly, since partitions 28, side molding members 31, bottom molding members 32, and upper and lower corner members 33, 34, etc., forming the mold 25 are integrated into one body, entire mold 25 can be simply cleaned at once while being suspended from the rails 21 unlike in the prior art in which each member should be cleaned separately.

Step 2: Spraying of a releasing agent, and assembling the mold

On completion of the surface cleaning of all the molds 25, a releasing agent is sprayed onto each surface of the molding partitions 28 by using a sprayer. Thereafter, each partition 28 is moved to the position of the base member 27 and brought into contact with each other. Then the bolts 44 (Figure 5) are passed through holes provided in the partitions 28 and the nuts 45, Figure 5 are fastened. The molding assembly 26 is thus assembled and set. This method can improve the productivity since spraying of the releasing agent, and assembling and setting of the molds are possible while suspending the molding partitions 28 downwardly from the rails 21. Step 3: Pouring of concrete mortar and vibrating the molds

The molding assembly 26 thus set in Step 2 is suspended from the rails 21 by the eyes 28a, the hooks 29a, the chains 29, and the sliders 22. When the base member 27 disposed below the assembly 26 is lifted by a fork lift, the assembly 26 is supported by the base member 27 and the chains 29 are loosened. Then, if the hooks 30a in the wire ropes 30 are hooked on the eyes 27c in the base member and the fork lift is lowered, the assembly 26 is supported only by the chains 29. Therefore, the assembly 26 has considerable freedom to vibrate. While operating a vibrator installed on the outer surface of the molding assembly 26 to vibrate the assembly, concrete mortar is introduced into the top of the assembly to fill the molds 25 in the gaps defined between the molding partitions 28. The concrete mortar is poured without clogging and pressed since the assembly 26 is suspended only by the four wire ropes 30 in the air and vibrates freely like a gong hung by a thread. The vibration may be performed on a vibration facility installed at a separate location. Then, the top surface of the assembly 26 is made even with a trowel, etc.

According to this step, concrete mortar can be put into all the molds in a single operation. Therefore the pouring work is considerably simplified.

Step 4: Curing

The molding assembly 26 with the concrete mortar filled and pressed is lifted by a fork lift, etc., to remove the wire ropes 30 from the base 27, transported to a suitable curing site, and then cured in a known manner.

Step 5: Removing the cured products from the molds

The molding assembly 26 containing the cured concrete mortar is carried by a fork lift and the hooks 29a are hooked again on the eyes 28a for the assembly to be supported by the rails 21. The nuts 45 are unfastened from the bolts 44, and then the molded products 50 are separated from the molds 25 by removing the partitions 28 one by one. Production of the molded products 50 is completed in this fashion.

Up to now, a method for assembling and removing one molding assembly 26 has been described. However, a plurality of molding assemblies 26 are used in actual manufacturing, and the sequence of the manufacturing steps may be different from the above-described. That is, in Step 4, the step of curing, when the assembly 26 to be cured is transferred to the curing site, the apparatus 20 is emptied. Therefore, another molding assembly 26, for example, an assembly 26 which has finished its cycle, may be introduced into the apparatus 20. Then, Step 5, the step of removing the molds may be performed by disassembling a new molding assembly 26, which has already been cured, and removing the molded products 50. In this way, according to the invention, the expensive apparatus 20 can always be used and several cycles of assembling and disassembling of the assemblies 26 can be completed per day. Therefore, the invention saves time and space, and is suitable for mass production.

In addition, concrete mortar can be poured at a vibration facility having a separate vibrating means when the assembly 26 is transferred to the facility, as explained in connection with Step 6, and then the assembly is transferred to the curing site and then cured. In this case, the support member 23, the wire rope support member 24, the base member 27, and the wire rope 30 can be omitted.

Figures 7a to 7c illustrate a second embodiment of the invention. The apparatus according to the second embodiment are provided with trapezoidal side molding members 51 and side end members 52 positioned alternately instead of the side molding members 31 of the first embodiment installed oppositely. The members 51 are spaced by a constant distance from the partition 28 against which they are faced, and the members 52 are designed to closely contact the partition 28 against which they are faced. In addition, since the shape of the side molding members 51 and the side end members 52 are simple trapezoidal columns, additional end pieces are not required. Therefore, the PC concrete slabs molded by the apparatus are the molded products 60 having a cross-section of a trapezoidal wave. Setting up two of the molded products 60 forms columns, as shown in Figure 7c, and Figure 7c shows an example in which the products 50 of the first embodiment and the products 60 of the second embodiment are used together.

Figures 8a and 8b illustrate a third embodiment of the invention in which side molding members 61 having a triangular section and installed complementarily, instead of the trapezoidal side molding members 51 and the side end members 52 of the second embodiment, to mold products 70 having the shape of triangular wave type slabs. Figures 9a and 9b illustrate the fourth embodiment of the invention. By this embodiment, products 72 in the form of sound absorbing wall with an array of recesses 72a are obtained. Such products 72 can be made by providing side molding members 71 of conical frustum shape.

It will be easily understood that the molded product of Figure 10 can be produced by installing trapezoidal side molding members oppositely on the partitions 28.

The molding partitions 28 can be made of steel plate or stainless steel plate.

The side molding members 31, 51, 61, 71, side end members 52, bottom molding members 32, and corner members 33, 34 are made by molding with steel or extruding with aluminum. Therefore, the portions forming the mold have good durability and can be used semi-permanently.

The apparatus according to the invention having the above-described construction has the following advantages:

First, since the molding partitions 28 forming the molds 25 can be moved horizontally with the sliders 22 installed on the rails 21, the heavy molds need not be moved one by one, for example, by an excavator. Therefore, cleaning of the molds and spraying of the releasing agent can be performed by moving the molding partitions 28 manually without difficulty, and waste of manpower and time are eliminated.

Second, since each of molding partitions 28 can be transferred to one side of the rails 21 and put in contact with an opposite one, a plurality of molds can be formed at one time and the assembling of the molding assembly 26 becomes easy. In addition, additional facilities for fixing the assembly are not needed.

Third, since the molding assembly 26 itself formed by combining a plurality of molding partitions 28 together can be vibrated by a vibrating means attached to the molding assembly when concrete mortar is poured thereinto, there is no waste of manpower and time as in the prior art in which each mold should be manually vibrated. Fourth, the molding assembly 26, filled with sufficiently dense concrete, can be easily transferred to a suitable curing site by an excavator, etc. Also, since the molding assembly 26 after hardening at the curing site can be transferred to the apparatus 20 and disassembled and the molded products are removed while the molding assembly is in the apparatus, these steps can be performed quite easily.

Fifth, since the molding partitions 28 of the molding assembly 26 in which the molded products are removed as described above can be cleaned and sprayed with the releasing agent in place, the down time of the expensive apparatus is substantially shortened. In other words, the effective operation time of the apparatus is extended and waste of facility investment is eliminated.

Sixth, since not only the side molding members 31 of the first embodiment but also the various other side molding members 51 , 61 , 71 and/or side end members 52 can be used on the molding partitions 28, various forms of molded products can be molded by the same apparatus. Therefore, facility investment is economical.

Seventh, since a plurality of molded products can be molded at one time with one molding assembly 26, the apparatus is suitable for mass production.

Although the above-described embodiments disclose the method and apparatus for manufacturing PC concrete slabs with concrete mortar, it can be understood that molding can be done with thermoplastic resins such as polyethylene, polypropylene, etc. Of course, in this case, additional top molding members and injection holes for injecting plastic must be provided. In addition, embedding of reinforcing members such as steel cores or steel nets can be performed by providing means capable of positioning the reinforcing members on the molding members in a conventional manner.

It will be understood that the invention may be modified in other specific forms without departing from the spirit or central characteristics of the invention. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.

Claims

We claim:

1. An apparatus for manufacturing PC concrete plate comprising a pair of rails 21 positioned parallel with each other at the upper portion of the apparatus; a plurality of sliders 22 slidable on the rails; and a molding assembly 26 formed by assembling a plurality of molding partitions 28 suspended separately from the sliders 22 so that they can be brought in contact with each other.

2. An apparatus according to Claim 1 wherein on the opposite sides of each molding partition 28 are provided a plurality of side molding members 31 which are fixed vertically, oppositely and with a constant spacing, bottom molding members 32 fixed transversely at the lower portion of the partition,

L-shaped upper corner members 33, each having one end contacting tightly with the upper corners of the side molding member 31 and another end extended to the upper edges of the molding partitions 28, and L-shaped lower corner members 34, each having one end tightly contacting the lower corner of the side molding member 31 and another end tightly contacting the upper edge of the bottom molding member 32.

3. An apparatus according to Claim 2, wherein said side molding member 31 comprises a hollow main body 41 , and two terminal members 42 connected to the body 41 with connecting portions 42a inserted into the ends of the body

41.

4. An apparatus according to Claim 3, wherein said terminal member 42 includes a top surface 42b being flush with the top surface of said body, inclined side walls 42c being flush with the side walls of said body, an end wall 42d, and connecting walls 42e having a curved shape between the end wall 42d and the side walls 42c.

5. An apparatus according to Claim 1, wherein on the opposite sides of each molding partition 28 are provided a plurality of trapezoidal side molding members 51, 52 positioned vertically and alternately, and bottom molding members 32 fixed transversely to tightly contact the lower ends of the side molding members 51, 52.

6. An apparatus according to Claim 1 , wherein on the opposite sides of each molding partition 28 are provided a plurality of side molding members of triangular column shape installed vertically and complementarily on facing surfaces of the molding partitions 28 adjacently positioned so that the edges thereof are spaced by a constant distance from the molding partitions 28, and bottom molding members 32 fixed transversely to tightly contact the lower ends of the side molding members 61.

7. An apparatus according to Claim 1 , wherein on the opposite sides of each molding partition 28 are provided end molding members of rectangular column shape installed oppositely on the two edges of the molding partitions, an array of side molding members 71 to form recesses 72a, and bottom molding members 32 fixed transversely on the lower edge of the molding partition 28.

8. An apparatus according to one of Claims 1 to 7, wherein the apparatus comprises a pair of support members 23 positioned parallel with each other outside said rails 21 , wire rope support members 24 fixed to the support members 23, wire ropes 30 fixed to the wire rope support members 24, a base member 27 positioned under the molding assembly 26, and removably suspended by said wire ropes.

9. An apparatus according to one of Claims 1 to 7 wherein a vibrating means is installed outside the molding partitions 28.

10. A method for manufacturing PC concrete plate comprising the steps of suspending horizontally movable molding partitions 28 to which molding members are attached, cleaning said molding partitions 28 and then spraying releasing agents onto said molding partitions 28, bringing into contact said molding partitions 28 with each other to form a molding assembly 26, pouring concrete mortar into the molding assembly 26 while the assembly is suspended over and vibrated on a base member 27, curing the concrete mortar in a curing site, and finally removing the cured products from the molds by disassembling the molding assembly 26 after completion of curing.

11. A method according to Claim 10 wherein said concrete pouring step is performed after transferring the molding assembly 26 from the apparatus onto a separate vibrating means.

12. A method according to Claim 10 wherein said molded product removing step is performed while the molding assembly 26 is suspended.

13. A molded product characterized in that it is manufactured by an apparatus according to one of Claims 1 to 9.

14. A molded product characterized in that it is manufactured by a method according to one of Claims 10 to 12.