GB1573271A - Mould for concrete samples - Google Patents

Description

(54) MOULD FOR CONCRETE SAMPLES (71) We, SCHLOSSER & CO. GmbH, a Body Corporate organised and existing under the Laws of the Federal Republic of Germany, of Michelbacher Hiitte, 6209 Aarbergen, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement-: The present invention relates to a mould suitable, for example, for the production of concrete samples or similar blanks for test purposes.

In order to be able to check the quality of concrete to be used, specimens are produced at construction sites, in concrete works and in testing centres. For this purpose, moulds in the shape of cubes or cylinders are most frequently used. It is desirable to be able to produce the test cubes as simply and as cheaply as possible.

On the other hand, the moulds must be true to size and have flat surfaces, and must also be sufficiently rigid to permit the concrete mass inserted therein to be vibrated and/or rammed in.

One known block mould disclosed in German Patent Specification No. DT-PS 1188 499 consists of a base plate and four side walls which are placed thereon and are connected to the base plate and to one another by means of a releasable system of bolts, or a fastening made up of clamps acting between the end walls and the base plate. All the components of this mould are of cast iron. It is consequently heavy and very robust. Dismantling and assembly of this mould takes some time.

Another known mould disclosed in German Patent Specification No. DT-GM 75 02 500 consists of a plastics mould unit, made in one piece, which is turned upside down to remove the test cube, the latter being forced out by compressed air fed through the base plate. This mould is of comparatively low weight. It is also unnecessary, for demoulding, to dismantle the mould, provided that forcing out the specimen by compressed air does in fact go smoothly. However, difficulties often arise at this juncture, because the test cube tends to get stuck in the mould, or to be tilted, if prior lubrication of the mould has been omitted, or if unsuitable release agents have been used, or if the compressed air can escape freely after initial loosening of the cube.

It has also been found that compacting by vibration and inertia is less effective than with a metal mould, apparently because the plastics material is relatively soft, as a result of which the base plate acts as a damper, and also because the mass required for effective inertia compacting is lacking.

The normal procedure is for the test cube moulds to be placed loose on a vibrating table, filled with concrete and, after filling, compressed for a period determined, with the aid of a time switch, of between 30 and 60 seconds, depending on the composition and consistency of the concrete, this being effected by vibration and severe jarring blows on the mould which is bouncing about on the table.

However, if the mould consists of a comparatively soft material, such as plastics, this will affect the intensity and time of compression. Finally, there is the danger that complete compression of the fresh concrete will not be achieved within the prescribed time.

The object of the present invention is therefore to provide a mould which may be lighter than a metal mould but nevertheless permits intensive transmission of the vibratory movements and inertia forces.

According to the present invention there is provided a mould having a base and a casing projecting from the upper side of the base, the base being made of metal or incorporating one or more metal parts, said base presenting an exposed metal face at its underside, casing being constituted by side walls inseparably connected together and being made wholly of plastics without external metal walls present.

A quick significant improvement, as compared with a mould made entirely of plastics is achieved if the base has a plastics portion in which there is integrally moulded a metal insert presenting said exposed metal face, or if the base has a plastics portion and a plurality of metal feet each presenting said exposed metal face.

An especially intensive level of compacting is however achieved if the entire base is made of metal, especially cast iron, the plastics casing being placed on this base with a secure method of fixing.

Removal of the specimen from such a non-dismantable mould may be facilitated if the mould comprises an ejector seated in said base and removable therefrom in the direction towards the interior of the mould, said ejector having a surface presented within the mould flush with an internally presented face of the base. With the aid of this ejector, the specimen can be extracted from the mould without using compressed air, and because the ejector can be of a relatively large area, there is in this case no reason to fear damage to the surface of the specimen, even if extraction is effected by an existing bending test machine (hydraulic cylinder), using a mechanical or hydraulic press, or by means of a hand tool.

In a preferred embodiment, the base has an opening to receive the ejector, the base having at said opening an internal peripheral shoulder on which an external peripheral flange of the ejector rests. The ejector advantageously projects downwardly beyond the underside of the base, and the projecting portion of the ejector has an external peripheral groove to receive an O-ring abutting the underside of the base, to retain the ejector removably in position. The ejector may advantageously be made of metal, and present said exposed face at its underside.

Further features of the invention will be apparent from the following description of embodiments of moulds which are shown in the drawings. In these drawings: Figure 1 is a vertical section through a first embodiment; Figure 2 is a similar section through a second embodiment; Figure 3 is a similar section through a third embodiment, and Figure 4 is a similar section through a mould in accordance with Figure 3, but with an additional ejection plate.

The mould in accordance with Figure 1 consists of a plastics mould unit, made in one piece, with a casing 1 and a base wall 2, the latter preferably having feet 3, for example at the corners of the mould.

Moulded into the base wall 2 of this plastics mould is a metal, preferably cast iron, insert 5 having an exposed bearing surface 6 in the same plane as the undersurfaces 7 of the feet, such that the mould may rest with its metal insert 5 on a vibrating device. A conventional air inlet aperture 8 is formed, for example, in the centre of the base wall and metal insert.

In the mould in accordance with Figure 2, the mould casing 11 and the base wall 12 are integrally moulded in plastics. In this case, the feet 13 are made of metal or cast iron. These feet can be screwed, glued or welded on, or alternatively moulded into the plastics base wall. The exposed bottom surfaces 17 form the bearing surfaces on the vibrating device. An air inlet aperture is indicated by 18. The metal feet 13 can also be connected to one another by a metal plate. The plastics mould, preferably with a somewhat thinner base wall portion, is then placed and secured on this metal base wall.

The mould in accordance with Figure 3 has a base wall 22 made entirely of metal or cast iron, on which the plastics casing 21 is placed. In this case, the metal base wall has itself the exposed face. For connecting purposes, the bolts 29 are provided, for example. The metal base wall 22 can also have small feet 23, and an air inlet aperture 28. The base wall could be joined to the casing by glueing, welding or moulding.

The construction of the mould shown in Figure 4, with a plastics casing 31, a metal base wall 32 and the feet 33, corresponds to a large extent to the mould in accordance with Figure 3. The metal base wall 32 has a larger opening 39, into which an ejector plate 40 is inserted. Preferably, this ejector plate is also made of metal. It can, however, be of another impact-resistant material. Its inner surace 41 joins flush with the inner surface of the base wall, while its outer surface 46 is slightly higher than the undersides 37 of the feet 33. To retain the ejector plate 40 in the base wall, an internal peripheral shoulder 47 is formed on the base wall, on which shoulder the ejector plate rests by its peripheral flange 48. To prevent the plate from falling accidentally out of this operating position, it has, on a level with the outer surface of the base wall, a circular groove 49 to receive an O-ring 50 which protrudes out of the circular groove, grips the base wall from below, and thus retains the ejector plate. On the other hand, this O-ring mounting can easily be overridden by imparting a blow. In this construction, an additional air inlet aperture 38 passes through the ejector plate. If it is desired to remove a specimen from this mould, the mould is turned over or upside down and, by exerting pressure on the ejector plate, the specimen is loosened in the mould and ultimately, as a result of the application of any aditional pressure on the ejector plate which may be necessary, separation of the specimen from the mould is achieved.

It is of course true that, in this case, it is also possible to assist the extraction of the specimen with the aid of compressed air, but this is unnecessary in the majority of cases, and it is for this reason that the air inlet opening is provided as a precautionary measure and is considerably smaller.

The invention is not limited to the embodiments described, but may be varied within the scope of the appended claims.

For example, the ejector plate may also be inserted in a plastics base wall. It may also assume the task of the metal insert 5 in accordance with Figure 1, if its outer surface 46 is in the same plane as the feet 37 (Figure 4). The ejector plate may also be mounted in a frusto-conical opening in the bottom wall.

WHAT WE CLAIM IS: 1. A mould having a base and a casing projecting from the upper side of the base, the base being made of metal or incorporating one or more metal parts, said base presenting an exposed metal face at its underside, the casing being constituted by side walls inseparably connected together and being made wholly of plastics without external metal walls present.

2. A mould, as claimed in claim 1, wherein the base has a plastics portion in which there is integrally moulded a metal insert presenting said exposed metal face.

3. A mould, as claimed in claim 1, wherein the base has a plastics portion and a plurality of metal feet each presenting said exposed metal face.

4. A mould, as claimed in either of claims 1 to 3, comprising an ejector seated in said base and removable therefrom in the direction towards the interior of the mould, said ejector having a surface presented within the mould flush with an internally presented face of the base.

5. A mould, as claimed in claim 4, wherein said base has an opening to receive the ejector, the base having at said opening an internal peripheral shoulder on which an external peripheral flange of the ejector rests.

6. A mould, as claimed in either of claims 4 and 5, wherein the ejector projects downwardly beyond the underside of the base, and the projecting portion of the ejector has an external peripheral groove to receive an O-ring abutting the underside of the base.

7. A mould, as claimed in any one of claims 4 to 6, wherein the ejector is made of metal and presents an exposed face at its underside.

8. A mould substantially as described herein with reference to Figure 1, or Figure 2, or Figure 3, or Figure 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. grips the base wall from below, and thus retains the ejector plate. On the other hand, this O-ring mounting can easily be overridden by imparting a blow. In this construction, an additional air inlet aperture 38 passes through the ejector plate. If it is desired to remove a specimen from this mould, the mould is turned over or upside down and, by exerting pressure on the ejector plate, the specimen is loosened in the mould and ultimately, as a result of the application of any aditional pressure on the ejector plate which may be necessary, separation of the specimen from the mould is achieved. It is of course true that, in this case, it is also possible to assist the extraction of the specimen with the aid of compressed air, but this is unnecessary in the majority of cases, and it is for this reason that the air inlet opening is provided as a precautionary measure and is considerably smaller. The invention is not limited to the embodiments described, but may be varied within the scope of the appended claims. For example, the ejector plate may also be inserted in a plastics base wall. It may also assume the task of the metal insert 5 in accordance with Figure 1, if its outer surface 46 is in the same plane as the feet 37 (Figure 4). The ejector plate may also be mounted in a frusto-conical opening in the bottom wall. WHAT WE CLAIM IS:

1. A mould having a base and a casing projecting from the upper side of the base, the base being made of metal or incorporating one or more metal parts, said base presenting an exposed metal face at its underside, the casing being constituted by side walls inseparably connected together and being made wholly of plastics without external metal walls present.

2. A mould, as claimed in claim 1, wherein the base has a plastics portion in which there is integrally moulded a metal insert presenting said exposed metal face.

3. A mould, as claimed in claim 1, wherein the base has a plastics portion and a plurality of metal feet each presenting said exposed metal face.

4. A mould, as claimed in either of claims 1 to 3, comprising an ejector seated in said base and removable therefrom in the direction towards the interior of the mould, said ejector having a surface presented within the mould flush with an internally presented face of the base.

5. A mould, as claimed in claim 4, wherein said base has an opening to receive the ejector, the base having at said opening an internal peripheral shoulder on which an external peripheral flange of the ejector rests.

6. A mould, as claimed in either of claims 4 and 5, wherein the ejector projects downwardly beyond the underside of the base, and the projecting portion of the ejector has an external peripheral groove to receive an O-ring abutting the underside of the base.

7. A mould, as claimed in any one of claims 4 to 6, wherein the ejector is made of metal and presents an exposed face at its underside.

8. A mould substantially as described herein with reference to Figure 1, or Figure 2, or Figure 3, or Figure 3 of the accompanying drawings.