METHOD FOR THE MANUFACTURE OF CONCRETE PRODUCTS

Abstract: The subject of the invention is a method for the manufacture of cast concrete products in which the concrete is poured into a casting mould (2), after a suitable period of time the mould (2, 3) is removed from around the concrete product (4) and the concrete product is then moved on for possible further processing. In the method according to the invention the mould material is manufactured from a heat expanding material and the temperature of the mould (2, 3) is altered after the pouring of the concrete causing the size of the mould to change due to the heat expansion and the mould (2, 3) and/or the concrete product are moved away from each other in order to remove the concrete product from the mould.

Description: METHODFORTHEMANUFACTUREOFCONCRETEPRODUCTS The subject of this invention is a method for the manufacture of cast concrete products in which the concrete is poured into a casting mould, after a suitable period of time the mould is removed from around the concrete product and the concrete product is then moved on for possible further processing. In the casting of concrete products various types of moulds are used according to the particular application concerned. The moulds are constructed from material suitable for the purpose and the moulds can be assembled and dismantled such that the same mould can be used over and over again in the manufacture of concrete products. The moulds or parts of the moulds are removed from around the concrete product once the concrete product has sufficiently set. Whenever the components of the moulds are dismantled after each casting and then reassembled prior to the ensuing casting, they can sometimes be damaged or develop excess tolerance due to wear. In these circumstances the dimensions of the mould are not very accurate. In addition to this, considerable time is spent on assembling and dismantling procedures. This is expensive and the manufacture of concrete products using this method is very time consuming. It is also a recognised method to use a material in the casting moulds for concrete products that can be removed by melting it away from around the concrete product. These kinds of casting moulds are suitable for specific purposes and it is not possible to utilise them in mass production. The purpose of this invention is to provide a method of manufacturing cast concrete products which can be utilised to eliminate the unsatisfactory aspects of the methods currently in use. In particular, the purpose of this invention is to provide a method which, when put into use, can produce a significant increase in the level of production capacity achieved using present methods and which can achieve a noticeable reduction in the handling time of the moulds. In addition, the purpose of the invention is to provide a method which, when put into use, will produce a significant improvement in the accuracy of the measurements of the moulds compared with present methods. The purpose of the invention is achieved by the method which possesses the characteristics presented in the appended claims. According to the invention the material used in the casting mould is made from a thermally expanding material. The temperature of the mould is altered following the casting of the concrete such that the size of the mould changes as a result of the thermal expansion and the mould and/or the concrete product are moved in different directions to each other to remove the concrete product from the mould. The adjustment to the temperature of the mould after the casting of the concrete causes the thermally expanding material to react by either expanding or contracting to the extent that a small gap forms between the concrete and the mould. This makes it possible for the mould to be removed from around the concrete product as a whole by raising it immediately after the concrete has set sufficiently or the concrete product can be removed from the mould. The concrete product is then moved on, possibly for further processing, and the next concrete product can then be cast immediately so that use can be made of the mould on a continuous basis. Working time is reduced significantly and production capacity is increased when there is no time consumption in the assembly and dismantling of the mould. The measurements of the concrete product are also accurate. In the advantageous application of this invention the temperature of the mould is raised after casting by heating the mould. When the mould is warmed up it undergoes a thermal expansion and shifts slightly away from the surface of the concrete. This method can be applied in such situations where the casting mould envelopes the concrete and the cast concrete is situated within the mould. The heating of the mould can be achieved by the use of various types of equipment which are especially suited for this purpose. The mould can be heated as an entire unit, for example, by using a suitable warming intermediate agent such as a hot liquid which is fed through the inside of the mould via suitable channels, tubes or other similar means. Alternatively, it is possible for the mould to be heated by using electrical methods or by other means suitable for this purpose. In the second advantageous embodiment of this invention the temperature of the mould is reduced after the concrete has been cast by cooling the mould. This method can be used in the situation where the mould is surrounded by the concrete. After the mould is cooled the mould contracts a little and the mould or the concrete product can be lifted away. This kind of mould is used, for example, when forming voids in the middle of a concrete product such as for door and window openings or other kinds of openings. The cooling is also carried out in this situation in a conventional manner by feeding a cooling intermediate agent either to the mould or to channels either inside it or on its surface or by other suitable means or by cooling the mould by some other means. In one advantageous embodiment of this invention, heat transmission equipment is connected to the mould which is used to adjust the temperature of the mould. This kind of equipment can be, for example, channels or the equivalent with which the intermediate agent is fed into the mould and removed from it. It is also possible to use, for example, heating or cooling cables or the equivalent. In the following, the invention is defined in more detail with reference to the attached illustrations, in which: Figure 1 demonstrates an application of the equipment viewed from above as an arrangement of the method according to the invention, figure 2 demonstrates the application described in figure 1 viewed from the side, figure 3 demonstrates a second application of the equipment viewed from above as an arrangement of the method, and figure 4 demonstrates the equipment in a third arrangement of the method. In the equipment shown in figures 1 - 3 there is a stiff frame form 2 situated on the flush mould 1 into which the concrete 4 is cast when manufacturing the concrete product. The arrangement shown in figure 3 also includes forms for window and door openings 3 situated within the mould 2. The casting of the concrete is carried out in this equipment in the conventional manner by feeding the cast concrete into the space between the mould and the forms for the window and door openings and by allowing the concrete to set. In the arrangement shown in figure 4, a base 5 is placed inside the frame mould 2. This base can be moved in a vertical and/or horizontal direction with respect to the frame mould. The frame mould 2 consists of high side walls 6 and a base board 7 on which the base 5 is positioned. This kind of equipment can be used to facilitate the manufacture of pillars or similar constructions. The base can be equipped with wheels or with lifting equipment. In the equipment shown in figures 1 and 4 heat transmission equipment (not shown in the figure) is connected to the mould 2 with which the temperature of the mould can be increased. In the equipment shown in figure 3 heat transmission equipment (not shown in the figure) is connected to the outer mould 2, with which the temperature of the mould can be increased, and heat transmission equipment (not shown in the figure) is connected to the forms for the window and door openings, with which the temperature of these moulds can be decreased by cooling them. In the manufacture of concrete products using the equipment shown in figures 1 - 4 the cast concrete is fed into the inside of the moulds. Once the concrete 4 has set sufficiently the outer moulds 2 are heated, and in the arrangement shown in figure 3, the inner moulds 3 are cooled at the same time such that the moulds, having thermally expanded or contracted, shift away from the cast concrete. In the arrangement shown in figure 4 it is sufficient for just the base to be heated when, as a result of its heat expansion, the side walls attached to it shift away from the concrete product. The temperature difference during the casting and heating time can be around 100°C depending on the invention arrangements where, for example, if the temperature of the cast concrete is 30°C the temperature of the cast mould is raised to around 120-130°C. This results in sufficient heat expansion in, for example, steel. Other temperatures and suitable materials can also be used in different arrangements. When the moulds 2, 3 separate from the concrete products a small gap is created between the concrete product and the moulds. Following this, the moulds can be removed as a whole from around the concrete product by lifting them away or, in the arrangement shown in figure 4, alternatively moving them in a sideways direction. It is also possible to keep the moulds in position and to remove the concrete products. This method results in a significant increase in the production capacity and reduces the time required in handling the moulds. The invention is not limited to the advantageous arrangements shown but can vary within the framework of the invention concept formed by the patent claims.

Claims: CLAIMS 1. A method for manufacturing concrete products in which concrete is poured into the mould (2), the mould (2, 3) is removed after a suitable period of time from around the concrete product (4) and the concrete product is then moved on for possible further processing, characterised in that the mould material is manufactured from a heat expanding material and that the temperature of the mould (2, 3) is altered after the pouring of the concrete causing the size of the mould to change due to the heat expansion and the mould (2, 3) and/or the concrete product are moved away from each other in order to remove the concrete product from the mould. 2. The method according to claim 1, characteri se d in that the temperature of the mould (2) or part of it is increased after the concrete is poured by heating the mould. 3. The method according to claim 1, characterised in that the temperature of the mould (3) is decreased after the concrete is poured by cooling the mould. 4. A method according to one of the claims 1-3, characterised in that heat transmission equipment is connected to the mould (2, 3) with which the temperature of the mould is changed.

Inventors: PAKISJAERVI HEIKKI, PAKISJAERVI, HEIKKI
Applicants: PAKISJAERVI HEIKKI, SPECIFINN OY, PAKISJAERVI, HEIKKI
Application year: 1997
Main classification: B28B7
IPC codes: B28B7