CA1046247A - Expansible mold for the manufacture of plaster pieces - Google Patents
Expansible mold for the manufacture of plaster piecesInfo
- Publication number
- CA1046247A CA1046247A CA216,245A CA216245A CA1046247A CA 1046247 A CA1046247 A CA 1046247A CA 216245 A CA216245 A CA 216245A CA 1046247 A CA1046247 A CA 1046247A
- Authority
- CA
- Canada
- Prior art keywords
- mold
- walls
- plaster
- deformable
- molding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
- B28B3/02—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein a ram exerts pressure on the material in a moulding space; Ram heads of special form
- B28B3/024—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein a ram exerts pressure on the material in a moulding space; Ram heads of special form the pressure on the material being transmitted through flexible or resilient wall parts, e.g. flexible cushions on the ramming surface, resilient wall parts pressing as a result of deformation caused by ram pressure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B7/00—Moulds; Cores; Mandrels
- B28B7/06—Moulds with flexible parts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B7/00—Moulds; Cores; Mandrels
- B28B7/24—Unitary mould structures with a plurality of moulding spaces, e.g. moulds divided into multiple moulding spaces by integratable partitions, mould part structures providing a number of moulding spaces in mutual co-operation
- B28B7/241—Detachable assemblies of mould parts providing only in mutual co-operation a number of complete moulding spaces
- B28B7/243—Detachable assemblies of mould parts providing only in mutual co-operation a number of complete moulding spaces for making plates, panels or similar sheet- or disc-shaped objects
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Mechanical Engineering (AREA)
- Moulds, Cores, Or Mandrels (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
- Forms Removed On Construction Sites Or Auxiliary Members Thereof (AREA)
- Press-Shaping Or Shaping Using Conveyers (AREA)
Abstract
EXPANSIBLE MOLD FOR THE MANUFACTURE
OF PLASTER PIECES
ABSTRACT OF THE DISCLOSURE
An expansible mold for the fabrication of plaster parts having reliefs in the side walls comprising at least two walls and non-compressible deformable parts between two parallel side edges of the walls in which, under pressure, the deformable parts acquire the profile to be imparted to the molded plaster part, and which retract from the molded plaster part upon re-lease of pressure to enable removal of the molded part without loss of a tight sealing relation with the mold.
OF PLASTER PIECES
ABSTRACT OF THE DISCLOSURE
An expansible mold for the fabrication of plaster parts having reliefs in the side walls comprising at least two walls and non-compressible deformable parts between two parallel side edges of the walls in which, under pressure, the deformable parts acquire the profile to be imparted to the molded plaster part, and which retract from the molded plaster part upon re-lease of pressure to enable removal of the molded part without loss of a tight sealing relation with the mold.
Description
10~24'7 This invention relates to an expansible mold for the manufacture of plaster parts or pieces.
Usually the molding of plaster pieces is performed by molds which can be disassembled, or have parts which are movable at the time of removal and of extraction of the piece, enabling the effects of friction on the mold walls to be avoided.
Nevertheless, the disadvantage of these molds consists principally of the fact that assembly of the mold movable parts cannot be obtained with sufficient accuracy, thereby giving rise to dimensional variations of the finished product.
More particularly, this inaccuracy is due to the mechanical clear-ances between the different movable parts and to the eventual retention within the clearance space of plaster particles which oppose mold closure.
A second process, more particularly practiced for the molding of prismatic pieces, consists in using molds equipped with fixed side walls, re-movable parts, for instance for the upper sides, and sliding parts for the lower sides.
After disengagement of the upper molding part, the removal of pieces can be carried out by displacing the mold bottom into the interior of the mold, for instance with the aid of hydraulic c~linders~ in order to eject the plaster through the upper part of the mold.
To enable such an operation, which requires very large stresses, it is necessary that the internal sides of the mold be quite flat, smooth, and have very great surface hardness in order to avoid any possibility of tearing up of the plaster surface and of abrasion of the mold surface.
This process, which requires molds of very high accuracy, is extremely expensive.
In order to reduce these disadvantages, this invention has as an object an expansible mold which, although it employs relative moving parts, essentially differs from known molds which can be disassembled or have movable .' ' . . ' ~ . . , ' ' ' 10~247 parts, in order to allow the free removal of the plaster product; at no time of its use is there a clearance between these parts enabling the inclusion :
of plaster particles that interfere with closure or impairs the accuracy of the mold. :-The invention provides a mold for the production of plaster parts ~-~ comprising at least two mold walls relatively movable between a closed ,J, position wherein ~hR aefine the mold space, and an expanded position wherein the spacing between the walls is greater than in the closed position, at least two deformable components positioned between outer ends of the said walls and in sealing ergagement therewith ini~both expanded and closed posi-tions, a feed opening communicating with the mold space for the introduction of plaster material to be molded, rigid spacers between said outer ends of the walls immediately outwardly of said deformable components having a width corresponding to the spacing between said walls when in closed position and positioned to be engaged by said walls in the closed position, a pressure means operative on at least one of said walls for displacement under pressure to be closed position whereby the deformable components are deformed in the direction of said pressure means and expanded into the space between the said mold walls to define the end walls of the mold space therebetween, said deformable components in response to release of pressure being returned to normal position between said walls by expanding to displace the mold walls away from each other to the expanded position while retracting lengthwise between the mold walls to release the article molded in the mold space.
In the case where the articles to be molded are parallelepiped and involve profiles on their side faces, both walls have parallel flat surfaces, :
and the two deformable components have two prismatic surfaces reciprocally opposite, the limit of deformation of the deformable components being deter-mined by interposing two metal blades between the walls outside the deformable components, and having a width corresponding to the desired thickness of the -. .
10~2~7 pieces to be molded.
Embodiments of the invention will be described hereinafter by way of non-restrictive example with reference to the accompanying drawings in which -Figures 1 and 2 are two horizontal sectional views of a mold usedfor the manufacture of plaster squares, respectively in positions of stripping (Figure 1) or of molding (Figure 2);
Figure 3 is a transversal elevational view of a set of molds iden-tical to that represented in Figures 1 and 2;
10Figure 4 is a horizontal section of a mold according to an alternate method, represented at the time of removal~ and Figure 5 is a vertical section of the mold of Figure 4 in the same phase of the manufacture showing another alternate method.
With reference to Figures 1 and 2, a mold 1 has two vertical and parallel walls 2 made of a material properly surface finished and without particular hardness, and two deformable substantially incompressible component parts 3 made of an elastic material having two reciprocally opposite prismatic -moulding surfaces 4. More particularly these component parts 3 can be made of elastomer, for instance of neoprene or of silicone, or of any other material having similar mechanical properties. The parts 3 are substantially inco~-pressible in the sense that when they are deformed under a force applied in one direction they expand in a transverse direction so that there is no significant reduction in volume.
This elastomer has the property of being able to collapse in a direction (arrow 5) under the effect of a force applied in the same direction.
Owing to the fact that this elastomer is incompressible, its volume remains constant and the dimensional loss resulting from this collapse in the direction of arrow 5 produces a directional increasing along the arrow 6.
The invention makes use of this property of the elastomer to enable _ 3 _ , ~ : . , . : . ' 10'~247 the removal of plaster pieces, the elastomer being subjected to a pressure at the time of casting the plaster and then relieved from mechanical stress at the time of removal. -.
- 3a -lO~Z47 As represented in Figure 2, the mold 1 is in molding position and the two internal faces of the walls 2, onto which the compressive forces of the elastomer are applied, are held in spaced relation at the thickness of the plaster square 7 through the medium of two metal parts 8 arranged on edge between the walls.
The component parts 3, compressed between the walls 2 of mold 1, in this state of deformation, have profiled molding surfaces 4, enabling molding of the sides of plaster square 7 to be effected.
Removal of the plaster square is obtained by releasing the forces on walls 2 and consequently on the component parts 3.
This release simultaneously opens a gap between the walls 2 and the plaster and, in consequence of the retracting of elastomer component parts 3, a gap at the surfaces 4 delineating the square thickness 7 (Figure 1).
Then square 7 can then be removed freely without stress and without friction, upwards or downwards, without any draw (draft angle formed in the mold walls to faciliate ejection), and without gaps occurring which would enable the inclusion of particles which might between the elastomer parts 3 and the walls 2 be detrimental to subsequent molding operations.
With reference to Figure 3, representing partially a set of molds 1 mounted in parallel, in which the walls 2 internal to the set are common to two adjacent molds, molding of the upper parts of squares 7 is carried out by molding component parts 9 fixed on the side edges of walls 2, reserving open-ings 10 for the casting, the surface of squares corresponding to the openings 10 which can be obtained by leveling. Molding of the lower side of square 7 is effected by a bottom 11 having profiles 12 for each of the molds 1 and on which the walls rest, this bottom being integral with a fixed base or even with the ground.
This arrangement of molds 1 makes evident an important advantage of the invention relating to the handling of plaster squares 7 immediately after removal :.....
'. ' . ''', ' ' :. '. ~ .' ' .' :
104t~Z47 According to the currentl~ employed processes, after removal it is known that it is necessary to convey the squares to a withdrawal station, storage station, drying station or a further storing station. This transport is particularly difficult owing to the fact that at the time of remsval, setting of the plaster has not been completed and the squares possess little mechanical strength. Consequently, it often happens that the plaster squares are damaged during such conveying.
This disadvantage is particularly aggravated in the case where non-homogeneous plasters whose setting time can vary considerably from one square to the other, are used. Effectively for the same molding time, frequently the squares from the same casting are not all transportable.
This invention reduces this disadvantage. It avoids the use of any gripping means on the squares, such as handling tongs or the like, and enables ejection of squares having very fair mechanical strength.
Thus it lends itself to automation and permits very high molding shot capacities to be obtained, even by using non-homogeneous plasters, more particularly of phosphogypsum.
For this purpose there is carried out transport of the whole molds themselves in which the squares are partially hermetically sealed, freeing of the lower side of the squares occurring at the time that the set of molds is raised in the first phase of conveying, owing to the fact that the bottom 11 is fixed.
When the set of molds 1 has been brought to the withdrawal station, removal occurs by removing the forces which keep the component parts 3 com-pressed, and by lifting the molds from the loosened squares 7, before return-ing the molds to the molding area. During this operation, ejection of squares occurs through the lower part of the mold which remains open in the absence of bottom 11.
Of course, in the case where the set of molds 2 comprises a plurality of parallel molds, as represented in Figure 2, compression of component elem~nts ^ 5 --~ ,, .
s 104~Z47 3 can be achieved by exerting a pressure on both outside walls of the set of molds, thus effecting deformation of said component parts 3.
It is advisable to specify that the invention is not restricted to the use of component parts 3 made of elastomers or of materials which are deformable, incompressible and elastic.
These component parts 3 can be replaced by devices enabling the same results to be obtained.
By way of example, these component parts can involve a sealed jacket made of plastic having an interior filled with a non-compressible fluid or some more with small-sized hard walls.
The invention also includes a component part 3 in which both spacing - -operations (spacing of its own lding surfaces and spacing of both walls 2) are independent. Such a component part 3 can be provided by two sealed jackets, each coupled with a hydraulic or pneumatic device, one of these jackets bear-ing the molding surface and the other jacket used only to fill the gap between walls 2 and the plaster piece. The operating of the hydraulic or pneumatic device is such that:
- for molding, the jacket bearing the molding surface is set under pres-sure whereas the second jacket is under low pressure;
- for removal, the second jacket is subjected to a pressure whereas the first jacket is under low pressure.
It is noticeable that this system allows spacings of molding sur-faces greater than previously obtained.
Lastly, the component part 3 can be composed of a mechanical device enabling simultaneously spacing of the molding surfaces 4 and of the walls 2 under the effect of pressure, for instance of a hydraulic or pneumatic cylinder.However, at the time of removal, more particularly owing to the fact of the pressure of a water skin between the flat surfaces respectively opposite the mold and the molded piece, it happens that this latter separates only on one side from the mold and clings on the other side onto one wall of this ~ 6 ~
.. .. . . . .. .. ~ .
10~6~47 latter. Then it is difficult to loosen the piece from this wall of the mold without damaging the plaster and such that the elastic component part of which a projection is engaged into the groove or slot it has formedl then exerts an assymetrical pressure on both flanks or edges of this hollow profile which, having a reduced thickness, consequently splits or breaks, as observed on a number of squares.
An alternate method applied to the mold consists in that the mold walls assembled by means of two deformable component parts are composed of plates which are flattened under the pressure effect exerted on said walls, enabling the mold to take its molding position, and which assume a non-flat shape when the mold is no longer subjected to the effect of these pressures at the time of removal.
To this latter alternate method of this invention, there is appended preferably a second means cooperating with the first and enabling avoidance of an injurious defect of the edges of the side faces having a middle recess of the plaster molded piece, formed by the deformable component parts when, at the time of removal, a non-symmetrical pressure is exerted at the time of relaxation of the deformable component part on edges having a reduced thickness of the recesses of the side faces of said molded piece. Effectively it is beneficial to insert a rigid profile piece into the deformable component part contributing to the forming of side faces having a central recess, without substantial elasticity the part, which projecting out of the deformable com-ponent part, has the profile of the recess desired.
An embodiment of this invention comprising these alternate methods is described hereinafter with the only purpose to illustrate the same. This description, performed with reference to the accompanying drawings, cannot be considered as a limitation of the scope of the invention.
In Figure 4 two substantially vertical walls 2' rest on a horizontal bottom 11, fixed on a framework (not shown) or the floor of a work-shop~ and equipped wlth desired profiles 12 during the molding operation, are represented .
10~6~47 in their equilibrium state without external stress at the time of stripping.
The curvature of these walls is exaggerated, being in practice hardly detect-able with the naked eye. Metal parts 9, mounted on the upper edge of walls
Usually the molding of plaster pieces is performed by molds which can be disassembled, or have parts which are movable at the time of removal and of extraction of the piece, enabling the effects of friction on the mold walls to be avoided.
Nevertheless, the disadvantage of these molds consists principally of the fact that assembly of the mold movable parts cannot be obtained with sufficient accuracy, thereby giving rise to dimensional variations of the finished product.
More particularly, this inaccuracy is due to the mechanical clear-ances between the different movable parts and to the eventual retention within the clearance space of plaster particles which oppose mold closure.
A second process, more particularly practiced for the molding of prismatic pieces, consists in using molds equipped with fixed side walls, re-movable parts, for instance for the upper sides, and sliding parts for the lower sides.
After disengagement of the upper molding part, the removal of pieces can be carried out by displacing the mold bottom into the interior of the mold, for instance with the aid of hydraulic c~linders~ in order to eject the plaster through the upper part of the mold.
To enable such an operation, which requires very large stresses, it is necessary that the internal sides of the mold be quite flat, smooth, and have very great surface hardness in order to avoid any possibility of tearing up of the plaster surface and of abrasion of the mold surface.
This process, which requires molds of very high accuracy, is extremely expensive.
In order to reduce these disadvantages, this invention has as an object an expansible mold which, although it employs relative moving parts, essentially differs from known molds which can be disassembled or have movable .' ' . . ' ~ . . , ' ' ' 10~247 parts, in order to allow the free removal of the plaster product; at no time of its use is there a clearance between these parts enabling the inclusion :
of plaster particles that interfere with closure or impairs the accuracy of the mold. :-The invention provides a mold for the production of plaster parts ~-~ comprising at least two mold walls relatively movable between a closed ,J, position wherein ~hR aefine the mold space, and an expanded position wherein the spacing between the walls is greater than in the closed position, at least two deformable components positioned between outer ends of the said walls and in sealing ergagement therewith ini~both expanded and closed posi-tions, a feed opening communicating with the mold space for the introduction of plaster material to be molded, rigid spacers between said outer ends of the walls immediately outwardly of said deformable components having a width corresponding to the spacing between said walls when in closed position and positioned to be engaged by said walls in the closed position, a pressure means operative on at least one of said walls for displacement under pressure to be closed position whereby the deformable components are deformed in the direction of said pressure means and expanded into the space between the said mold walls to define the end walls of the mold space therebetween, said deformable components in response to release of pressure being returned to normal position between said walls by expanding to displace the mold walls away from each other to the expanded position while retracting lengthwise between the mold walls to release the article molded in the mold space.
In the case where the articles to be molded are parallelepiped and involve profiles on their side faces, both walls have parallel flat surfaces, :
and the two deformable components have two prismatic surfaces reciprocally opposite, the limit of deformation of the deformable components being deter-mined by interposing two metal blades between the walls outside the deformable components, and having a width corresponding to the desired thickness of the -. .
10~2~7 pieces to be molded.
Embodiments of the invention will be described hereinafter by way of non-restrictive example with reference to the accompanying drawings in which -Figures 1 and 2 are two horizontal sectional views of a mold usedfor the manufacture of plaster squares, respectively in positions of stripping (Figure 1) or of molding (Figure 2);
Figure 3 is a transversal elevational view of a set of molds iden-tical to that represented in Figures 1 and 2;
10Figure 4 is a horizontal section of a mold according to an alternate method, represented at the time of removal~ and Figure 5 is a vertical section of the mold of Figure 4 in the same phase of the manufacture showing another alternate method.
With reference to Figures 1 and 2, a mold 1 has two vertical and parallel walls 2 made of a material properly surface finished and without particular hardness, and two deformable substantially incompressible component parts 3 made of an elastic material having two reciprocally opposite prismatic -moulding surfaces 4. More particularly these component parts 3 can be made of elastomer, for instance of neoprene or of silicone, or of any other material having similar mechanical properties. The parts 3 are substantially inco~-pressible in the sense that when they are deformed under a force applied in one direction they expand in a transverse direction so that there is no significant reduction in volume.
This elastomer has the property of being able to collapse in a direction (arrow 5) under the effect of a force applied in the same direction.
Owing to the fact that this elastomer is incompressible, its volume remains constant and the dimensional loss resulting from this collapse in the direction of arrow 5 produces a directional increasing along the arrow 6.
The invention makes use of this property of the elastomer to enable _ 3 _ , ~ : . , . : . ' 10'~247 the removal of plaster pieces, the elastomer being subjected to a pressure at the time of casting the plaster and then relieved from mechanical stress at the time of removal. -.
- 3a -lO~Z47 As represented in Figure 2, the mold 1 is in molding position and the two internal faces of the walls 2, onto which the compressive forces of the elastomer are applied, are held in spaced relation at the thickness of the plaster square 7 through the medium of two metal parts 8 arranged on edge between the walls.
The component parts 3, compressed between the walls 2 of mold 1, in this state of deformation, have profiled molding surfaces 4, enabling molding of the sides of plaster square 7 to be effected.
Removal of the plaster square is obtained by releasing the forces on walls 2 and consequently on the component parts 3.
This release simultaneously opens a gap between the walls 2 and the plaster and, in consequence of the retracting of elastomer component parts 3, a gap at the surfaces 4 delineating the square thickness 7 (Figure 1).
Then square 7 can then be removed freely without stress and without friction, upwards or downwards, without any draw (draft angle formed in the mold walls to faciliate ejection), and without gaps occurring which would enable the inclusion of particles which might between the elastomer parts 3 and the walls 2 be detrimental to subsequent molding operations.
With reference to Figure 3, representing partially a set of molds 1 mounted in parallel, in which the walls 2 internal to the set are common to two adjacent molds, molding of the upper parts of squares 7 is carried out by molding component parts 9 fixed on the side edges of walls 2, reserving open-ings 10 for the casting, the surface of squares corresponding to the openings 10 which can be obtained by leveling. Molding of the lower side of square 7 is effected by a bottom 11 having profiles 12 for each of the molds 1 and on which the walls rest, this bottom being integral with a fixed base or even with the ground.
This arrangement of molds 1 makes evident an important advantage of the invention relating to the handling of plaster squares 7 immediately after removal :.....
'. ' . ''', ' ' :. '. ~ .' ' .' :
104t~Z47 According to the currentl~ employed processes, after removal it is known that it is necessary to convey the squares to a withdrawal station, storage station, drying station or a further storing station. This transport is particularly difficult owing to the fact that at the time of remsval, setting of the plaster has not been completed and the squares possess little mechanical strength. Consequently, it often happens that the plaster squares are damaged during such conveying.
This disadvantage is particularly aggravated in the case where non-homogeneous plasters whose setting time can vary considerably from one square to the other, are used. Effectively for the same molding time, frequently the squares from the same casting are not all transportable.
This invention reduces this disadvantage. It avoids the use of any gripping means on the squares, such as handling tongs or the like, and enables ejection of squares having very fair mechanical strength.
Thus it lends itself to automation and permits very high molding shot capacities to be obtained, even by using non-homogeneous plasters, more particularly of phosphogypsum.
For this purpose there is carried out transport of the whole molds themselves in which the squares are partially hermetically sealed, freeing of the lower side of the squares occurring at the time that the set of molds is raised in the first phase of conveying, owing to the fact that the bottom 11 is fixed.
When the set of molds 1 has been brought to the withdrawal station, removal occurs by removing the forces which keep the component parts 3 com-pressed, and by lifting the molds from the loosened squares 7, before return-ing the molds to the molding area. During this operation, ejection of squares occurs through the lower part of the mold which remains open in the absence of bottom 11.
Of course, in the case where the set of molds 2 comprises a plurality of parallel molds, as represented in Figure 2, compression of component elem~nts ^ 5 --~ ,, .
s 104~Z47 3 can be achieved by exerting a pressure on both outside walls of the set of molds, thus effecting deformation of said component parts 3.
It is advisable to specify that the invention is not restricted to the use of component parts 3 made of elastomers or of materials which are deformable, incompressible and elastic.
These component parts 3 can be replaced by devices enabling the same results to be obtained.
By way of example, these component parts can involve a sealed jacket made of plastic having an interior filled with a non-compressible fluid or some more with small-sized hard walls.
The invention also includes a component part 3 in which both spacing - -operations (spacing of its own lding surfaces and spacing of both walls 2) are independent. Such a component part 3 can be provided by two sealed jackets, each coupled with a hydraulic or pneumatic device, one of these jackets bear-ing the molding surface and the other jacket used only to fill the gap between walls 2 and the plaster piece. The operating of the hydraulic or pneumatic device is such that:
- for molding, the jacket bearing the molding surface is set under pres-sure whereas the second jacket is under low pressure;
- for removal, the second jacket is subjected to a pressure whereas the first jacket is under low pressure.
It is noticeable that this system allows spacings of molding sur-faces greater than previously obtained.
Lastly, the component part 3 can be composed of a mechanical device enabling simultaneously spacing of the molding surfaces 4 and of the walls 2 under the effect of pressure, for instance of a hydraulic or pneumatic cylinder.However, at the time of removal, more particularly owing to the fact of the pressure of a water skin between the flat surfaces respectively opposite the mold and the molded piece, it happens that this latter separates only on one side from the mold and clings on the other side onto one wall of this ~ 6 ~
.. .. . . . .. .. ~ .
10~6~47 latter. Then it is difficult to loosen the piece from this wall of the mold without damaging the plaster and such that the elastic component part of which a projection is engaged into the groove or slot it has formedl then exerts an assymetrical pressure on both flanks or edges of this hollow profile which, having a reduced thickness, consequently splits or breaks, as observed on a number of squares.
An alternate method applied to the mold consists in that the mold walls assembled by means of two deformable component parts are composed of plates which are flattened under the pressure effect exerted on said walls, enabling the mold to take its molding position, and which assume a non-flat shape when the mold is no longer subjected to the effect of these pressures at the time of removal.
To this latter alternate method of this invention, there is appended preferably a second means cooperating with the first and enabling avoidance of an injurious defect of the edges of the side faces having a middle recess of the plaster molded piece, formed by the deformable component parts when, at the time of removal, a non-symmetrical pressure is exerted at the time of relaxation of the deformable component part on edges having a reduced thickness of the recesses of the side faces of said molded piece. Effectively it is beneficial to insert a rigid profile piece into the deformable component part contributing to the forming of side faces having a central recess, without substantial elasticity the part, which projecting out of the deformable com-ponent part, has the profile of the recess desired.
An embodiment of this invention comprising these alternate methods is described hereinafter with the only purpose to illustrate the same. This description, performed with reference to the accompanying drawings, cannot be considered as a limitation of the scope of the invention.
In Figure 4 two substantially vertical walls 2' rest on a horizontal bottom 11, fixed on a framework (not shown) or the floor of a work-shop~ and equipped wlth desired profiles 12 during the molding operation, are represented .
10~6~47 in their equilibrium state without external stress at the time of stripping.
The curvature of these walls is exaggerated, being in practice hardly detect-able with the naked eye. Metal parts 9, mounted on the upper edge of walls
2', give the desired shape to the upper dihedrons of the squares; a casting hole 10 is provided between these parts for enabling the casting of the tempered plaster which spreads into the squares 7.
In Figure 5 can be seen the walls 2', the molded piece 7, the de-formable component parts 3 and 3' of which one 3 has a recess whereas in the ;-other 3' is inserted a rigid piece 13, (for instance made of polished metal 13) whose profile corresponds to that of the groove it is to form; metal blades 8 are used as thrust for component parts 3 and 3' and maintain the interval between the walls 2 at the time of removal.
Of course, the separate molds represented can be coupled in series as has been heretofore described, each wall being common to two adjoining molds, except those arranged at the ends of the set. The whole of the alter-nate methods or a part of the same described previously can be embodied in the improved mold of the present invention.
For performing the plaster molding, the molds are placed on their bottom 11, and on at least one of the walls 2' there is exerted a pressure sufficient to bring the initially bent walls 2' to a fairly planar form, their spacing and their positon being maintained by the bottom 11 and the different parts 9 and 8. This pressure can be exerted in a fairly homogeneous manner by a hydraulic or pneumatic transmission on a rigid flat plate (not represented) having a surface fairly equal to these of walls 3. These walls 2', such as represented in the figures, are bent. The sagitta corresponding to the great-est distance between a point of the concavity of the bend and the position of the same point when the planar shape is obtained, is in the range of 1/1000 of the major dîmension, that is to say, m general, of the flat faces of the piece to be molded, or in other words for squares having usual sizes from
In Figure 5 can be seen the walls 2', the molded piece 7, the de-formable component parts 3 and 3' of which one 3 has a recess whereas in the ;-other 3' is inserted a rigid piece 13, (for instance made of polished metal 13) whose profile corresponds to that of the groove it is to form; metal blades 8 are used as thrust for component parts 3 and 3' and maintain the interval between the walls 2 at the time of removal.
Of course, the separate molds represented can be coupled in series as has been heretofore described, each wall being common to two adjoining molds, except those arranged at the ends of the set. The whole of the alter-nate methods or a part of the same described previously can be embodied in the improved mold of the present invention.
For performing the plaster molding, the molds are placed on their bottom 11, and on at least one of the walls 2' there is exerted a pressure sufficient to bring the initially bent walls 2' to a fairly planar form, their spacing and their positon being maintained by the bottom 11 and the different parts 9 and 8. This pressure can be exerted in a fairly homogeneous manner by a hydraulic or pneumatic transmission on a rigid flat plate (not represented) having a surface fairly equal to these of walls 3. These walls 2', such as represented in the figures, are bent. The sagitta corresponding to the great-est distance between a point of the concavity of the bend and the position of the same point when the planar shape is obtained, is in the range of 1/1000 of the major dîmension, that is to say, m general, of the flat faces of the piece to be molded, or in other words for squares having usual sizes from
3/10 to 8/10 of a millimeter. T~ese walls can ~e performed b~ d~spo~ing on an , ,j t.~
.
104~Z~7 iron framework, two sheet iron plates having at least a smooth surface and separated one from the other by a fillîng having a constant thickness. At least two of the sides opposite of the framework are bent. By becoming flat under the effect of the pressure, these walls squash the deformable pieces and make them spread in the only direction which is not restricted, that is to say towards the interior of the mold. Then the plaster is cast, and after-wards when a degree of setting sufficient to make it non-deformable under the effect of its own weight has occurred, for instance the mold or the set of molds is carried to the area where the squares have to be dried, and the pressure is released. The deformable component parts, by returning to their initial shape, push aside the walls which at the same time bow allowing air to penetrate between them and the plaster. The rigid inserted part 3 follows the general shrinkage direction in a translation in the axial plane of the groove without exerting an assymetrical pressure on either side of this groove even if one of the vertical walls returns to its equilibrium shape more rapidly than the other or if a local adherence occurs.
Preferably the thickness of the walls is selected in such a way that there is sufficient spacing between the squares to effect drying by air circu-lation propelled by an impeller, this being made without difficulty by a single vertical displacement of the mold. For instance this spacing is in the range from 20 to 30 mm for squares of 30 mm in thickness.
.
104~Z~7 iron framework, two sheet iron plates having at least a smooth surface and separated one from the other by a fillîng having a constant thickness. At least two of the sides opposite of the framework are bent. By becoming flat under the effect of the pressure, these walls squash the deformable pieces and make them spread in the only direction which is not restricted, that is to say towards the interior of the mold. Then the plaster is cast, and after-wards when a degree of setting sufficient to make it non-deformable under the effect of its own weight has occurred, for instance the mold or the set of molds is carried to the area where the squares have to be dried, and the pressure is released. The deformable component parts, by returning to their initial shape, push aside the walls which at the same time bow allowing air to penetrate between them and the plaster. The rigid inserted part 3 follows the general shrinkage direction in a translation in the axial plane of the groove without exerting an assymetrical pressure on either side of this groove even if one of the vertical walls returns to its equilibrium shape more rapidly than the other or if a local adherence occurs.
Preferably the thickness of the walls is selected in such a way that there is sufficient spacing between the squares to effect drying by air circu-lation propelled by an impeller, this being made without difficulty by a single vertical displacement of the mold. For instance this spacing is in the range from 20 to 30 mm for squares of 30 mm in thickness.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A mold for the production of plaster parts comprising at least two mold walls relatively movable between a closed position wherein they define the mold space, and an expanded position wherein the spacing between the walls is greater than in the closed position, at least two deformable compon-ents positioned between outer ends of the said walls and in sealing engagement therewith in both expanded and closed positions, a feed opening communicating with the mold space for the introduction of plaster material to be molded, said deformable components having a width corresponding to spacing between said walls when in closed position and positioned to be engaged by said walls in the closed position, a pressure means operative on at least one of said walls for displacement under pressure to the closed position, whereby the deformable components are deformed in the direction of said pressure means and expanded into the space between the said mold walls to define the end walls of the mold space therebetween, said deformable components in response to release of pressure being returned to normal position between said walls by expanding to displace the mold walls away from each other to the expanded position while retracting lengthwise between the mold walls to release the article molded in the mold space.
2. A mold according to claim 1, wherein said deformable components are made of a resilient elastic material.
3. A mold according to claim 1, wherein said deformable components are essentially composed of a jacket made of an elastic material having an interior filled with a non-compressible fluid.
4. A mold according to claim 1 in which the deformable components comprise two sealed elastic jackets coupled with a hydraulic or pneumatic device, one of these jackets bearing a molding profile and the other serving only to obtain the spacing of the walls.
5. A mold according to claim 1, wherein each of the deformable compon-ents comprises a molding surface and mechanical device enabling the spacing of said molding surfaces and the spacing of the above-mentioned walls to be effected simultaneously.
6. A mold according to claim 1 for the production of plaster squares comprising moldings on their side faces, wherein said two walls are flat and parallel and said deformable components have surfaces provided with reliefs reciprocally opposite, said rigid spacers comprising two metal blades positioned outwardly of the internal surface of the mold.
7. A mold according to claim 1, wherein molding of a lower edge surface of the plaster parts is effected by means of a base provided with a desired profile.
8. A mold according to claim 7, wherein said base is fixed whereas the rest of the mold is movable to effect displacement of the plaster parts with respect to the base before plaster setting is complete.
9. A mold assembly comprising a set of molds as claimed in claim 1, 2 or 6 in which a plurality of said molds are arranged contiguously, with mold walls located in the inside of the said set being common to two adjacent molds.
10. Molt according to claim 1, 2 or 6 wherein said walls are composed of plates which become substantially planar under the effect of actuation of said pressure means, and which assume a non-flat shape when the mold is no longer subjected to the effect of said pressure means at the time of removal of the molded parts.
11. Mold according to claim 1, 2 or 6 comprising a rigid insert provided in one of said deformable components the insert projecting from said one component towards the interior of the mold and having a profile corres-ponding to that of a recess to be molded in the end of the plaster part.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7345320A FR2254944A5 (en) | 1973-12-18 | 1973-12-18 | Expandable mould for making plaster articles - comprising surfaces with relief patterns |
| FR7439104A FR2292564A2 (en) | 1974-11-29 | 1974-11-29 | EXTENSIBLE MOLD FOR THE MANUFACTURE OF PLASTER PARTS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1046247A true CA1046247A (en) | 1979-01-16 |
Family
ID=26218081
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA216,245A Expired CA1046247A (en) | 1973-12-18 | 1974-12-17 | Expansible mold for the manufacture of plaster pieces |
Country Status (20)
| Country | Link |
|---|---|
| JP (1) | JPS5315883B2 (en) |
| AR (1) | AR206137A1 (en) |
| AT (1) | AT340300B (en) |
| BR (1) | BR7410548D0 (en) |
| CA (1) | CA1046247A (en) |
| CH (1) | CH597991A5 (en) |
| DD (1) | DD115062A5 (en) |
| ES (1) | ES432990A1 (en) |
| FI (1) | FI366074A (en) |
| GB (1) | GB1469847A (en) |
| IE (1) | IE40332B1 (en) |
| IL (1) | IL46273A (en) |
| IT (1) | IT1057889B (en) |
| MX (1) | MX3672E (en) |
| NL (1) | NL179117C (en) |
| OA (1) | OA04953A (en) |
| PL (1) | PL100085B1 (en) |
| RO (1) | RO82091A (en) |
| SE (1) | SE418592B (en) |
| YU (1) | YU39656B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1572758A (en) * | 1976-11-11 | 1980-08-06 | Leisure Life | Frame structure for casting building panels |
| JPS57162825U (en) * | 1981-04-02 | 1982-10-14 | ||
| ES2166341B1 (en) * | 2000-08-25 | 2003-04-01 | Arcadio Jose Antonio Martin | METHOD FOR THE MANUFACTURE OF TABIQUES OR SHELVES OF ESCAYOLA AND CORRESPONDING MACHINE FOR THE MANUFACTURE AND DISASSEMBLY OF SUCH TABIQUES OR ESCAYOLA SHELVES. |
| CN112060296B (en) * | 2020-08-21 | 2022-06-24 | 湖南五新模板有限公司 | Steel-plastic combined concrete prefabricated part mold and demolding method thereof |
-
1974
- 1974-01-01 AR AR256939A patent/AR206137A1/en active
- 1974-12-16 PL PL1974176500A patent/PL100085B1/en unknown
- 1974-12-16 MX MX745679U patent/MX3672E/en unknown
- 1974-12-17 IL IL46273A patent/IL46273A/en unknown
- 1974-12-17 NL NLAANVRAGE7416422,A patent/NL179117C/en not_active IP Right Cessation
- 1974-12-17 CA CA216,245A patent/CA1046247A/en not_active Expired
- 1974-12-17 CH CH1677374A patent/CH597991A5/xx not_active IP Right Cessation
- 1974-12-17 BR BR10548/74A patent/BR7410548D0/en unknown
- 1974-12-17 RO RO7480823A patent/RO82091A/en unknown
- 1974-12-17 ES ES432990A patent/ES432990A1/en not_active Expired
- 1974-12-17 SE SE7415856A patent/SE418592B/en not_active IP Right Cessation
- 1974-12-17 DD DD183114A patent/DD115062A5/xx unknown
- 1974-12-17 IT IT54598/74A patent/IT1057889B/en active
- 1974-12-17 YU YU3352/74A patent/YU39656B/en unknown
- 1974-12-17 FI FI3660/74A patent/FI366074A/fi unknown
- 1974-12-18 JP JP14552774A patent/JPS5315883B2/ja not_active Expired
- 1974-12-18 IE IE2610/74A patent/IE40332B1/en unknown
- 1974-12-18 OA OA55373A patent/OA04953A/en unknown
- 1974-12-18 AT AT1012274A patent/AT340300B/en not_active IP Right Cessation
- 1974-12-18 GB GB5469474A patent/GB1469847A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| BR7410548D0 (en) | 1975-09-02 |
| ATA1012274A (en) | 1977-03-15 |
| ES432990A1 (en) | 1976-09-01 |
| RO82091B (en) | 1983-06-30 |
| AR206137A1 (en) | 1976-06-30 |
| OA04953A (en) | 1980-10-31 |
| AT340300B (en) | 1977-12-12 |
| PL100085B1 (en) | 1978-08-31 |
| IT1057889B (en) | 1982-03-30 |
| JPS5171365A (en) | 1976-06-21 |
| JPS5315883B2 (en) | 1978-05-27 |
| SE418592B (en) | 1981-06-15 |
| IL46273A (en) | 1977-12-30 |
| YU335274A (en) | 1982-02-28 |
| NL7416422A (en) | 1975-06-20 |
| NL179117C (en) | 1986-07-16 |
| CH597991A5 (en) | 1978-04-28 |
| SE7415856L (en) | 1975-06-19 |
| IE40332B1 (en) | 1979-05-09 |
| DD115062A5 (en) | 1975-09-12 |
| GB1469847A (en) | 1977-04-06 |
| NL179117B (en) | 1986-02-17 |
| YU39656B (en) | 1985-03-20 |
| FI366074A (en) | 1975-06-19 |
| RO82091A (en) | 1983-07-07 |
| IL46273A0 (en) | 1975-03-13 |
| IE40332L (en) | 1975-06-18 |
| MX3672E (en) | 1981-04-21 |
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